JPH09269435A - Optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical connector provided with a waveguide type optical filter having a high light cut-off rate. SOLUTION: This optical connector is provided with at least the waveguide type optical filter 12 provided with a grating 126 of a prescribed reflection wavelength and a plug attached to the tip of the optical filter 12. Particularly, the grating 126 is provided in the position being the tip part of the optical filter 12 and housed in the plug. Further, various light shielding structures for preventing propagation of useless light from the grating 126 are provided in the optical connector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an optical connector for connecting an optical filter having a waveguide structure and an optical element such as an optical fiber or a semiconductor device.

[0002]

2. Description of the Related Art OTDR (Optical Time Dmain Reflect
In an inspection system of an optical line using an inspection device such as an ometry device, an optical filter that reflects inspection light of a predetermined wavelength is usually provided in the optical line. This optical filter has
It has the function of blocking the inspection light and preventing it from being sent to the subscriber's house. It also reflects the inspection light that has propagated through the optical line and sends it back to the inspection device, checking whether there are any obstacles in the optical line and It has a function of detecting optical transmission characteristics.

As an optical filter used in an inspection system of an optical line, a waveguide having a region (hereinafter referred to as a filter region) having an optical filter function in a core of an optical waveguide (optical fiber, thin film waveguide, etc.) is provided. A structured optical filter is particularly suitable. For example, an optical fiber type optical filter can be obtained by forming a filter region at a predetermined portion of a communication optical fiber used as an optical line, and such an optical filter itself can be used as an optical line. is there. Therefore, if a plug is attached to one end of an optical fiber type optical filter to form an optical connector, its handling becomes easy. Therefore, if an optical line inspection system is configured by using an optical fiber type optical filter, it is not necessary to insert a filter component in the optical line as in the case of using a dielectric multilayer filter, and signal light loss is eliminated. Is less. In addition, a thin-film waveguide type optical filter having a filter region provided in the thin-film waveguide is convenient because it can not only reflect the inspection light but also branch and output the signal light that has passed through the filter region. There are many points.

A grating has been conventionally used as a filter region of an optical filter having such a waveguide structure. The grating here is a region in the optical waveguide in which the effective refractive index changes periodically between the minimum value and the maximum value along the optical axis (longitudinal direction). JP 6
As described in Japanese Patent Publication No. 2-500052, the above-mentioned grating is formed by irradiating a quartz glass doped with germanium with ultraviolet light having an interference pattern of a predetermined pitch. This is because the refractive index of glass rises according to the light intensity distribution of the interference pattern of the ultraviolet light. The grating formed in the core of the optical waveguide reflects light having a narrow wavelength width (hereinafter, referred to as the reflection wavelength of the grating) centered on a predetermined reflection wavelength (Bragg wavelength) among the light traveling in the optical waveguide. It is known that the reflection wavelength of this grating is determined according to the period (grating pitch) of the grating.

[0005]

However, in the optical filter having the above-mentioned waveguide structure, the light having the reflection wavelength of the grating is not reflected by the grating and passes through the filter region in which the grating is built. There is light (mainly light propagating through the cladding region from the grating). Therefore, the optical connector provided with the optical filter has a problem that the filter function of blocking the light of the predetermined wavelength (reflection wavelength of the grating) cannot be sufficiently exerted depending on the part where the grating is provided.

The present invention has been made to solve the above problems, and an object thereof is to provide an optical connector having a waveguide type optical filter having a high light blocking rate.

[0007]

An optical connector according to the present invention has at least (a) a core having a predetermined refractive index as a part of a transmission path, and a refractive index lower than that of the core, and An optical filter having a waveguide structure composed of a clad covering the outer periphery of the core, and a grating for reflecting light of a predetermined wavelength provided at a predetermined portion of the core; and (b) of the optical filter. A plug is attached to the optical filter while having a space for accommodating a part of the optical filter and having a tip portion including one end surface of the optical filter accommodated in the space.

As a result of examining the conventional optical connector including the optical filter from the viewpoints of the performance of the optical filter, the manufacture of the optical connector, etc., the inventors of the present invention examined the optical line having the optical waveguide structure for the optical line. It has been concluded that for use in a system, the grating provided in the core of the optical filter is preferably housed in an optical connector for optical connection between the inspection system and the subscriber terminal. Therefore, in the optical connector according to the present invention, as described above, in order to improve the performance of the optical filter and facilitate the manufacture of the optical connector, the grating is the tip portion of the optical filter and is in the space of the plug. It is characterized by being stored in.

In general, when connecting between transmission lines, an optical connector is a plug attached to the tip of each optical fiber cable (also called an optical cord) 11a, 11b to be connected, as shown in FIG. 1 and an alignment sleeve 21 for optically coupling the plugs 1 with each other. On the other hand, when connecting a transmission line to a semiconductor device (for example, a light receiving element) to the transmission line, the optical connector is a ferrule 24 attached to the end of the optical fiber cable 22, as shown in FIG.
(Included in the plug 1), a sleeve 20a for housing the ferrule 24, and a part of an optical module 20 including at least a holder 20b having an optical element 20d mounted on the main surface of a stem 20c.

The plug is called an optical connector with a cord because it may be sold by itself in a state of being attached to the tip of an optical fiber cable. Therefore, in this specification, a member composed of an optical fiber cable and a plug or ferrule attached to the end of the optical fiber cable is also simply referred to as an optical connector. Further, in this specification, an optical fiber
Cables (or optical cords) include not only cables (cord) with the outer periphery of a single optical fiber coated with plastic, but also ribbon-type cables (cord) with plastic coating of multiple optical fibers. (See FIG. 2).

However, as described above, even in the optical connector which accommodates the region (filter region) of the optical filter in which the grating is provided, the light having the predetermined wavelength (reflection wavelength of the grating) to be reflected by the grating is used. However, there is light that passes through the filter region without being reflected by the grating (mainly light that propagates from the grating to the cladding region). Therefore, when viewed from the emission end side of the optical filter, the filter function of blocking the light to be reflected by the grating may not be sufficiently exerted.

Therefore, the optical connector according to the present invention is a part of the light to be reflected by the grating, which is the light radiated from the grating to the clad, and the light from the filter area of the optical filter provided with the grating to the optical filter It is characterized by further comprising a light shielding structure for preventing the propagation of light propagating toward the one end face.

In particular, the optical connector according to the present invention has the following two embodiments depending on the position of the housed grating.

That is, the plug has (a) a through hole for accommodating a part of the optical filter (for example, an optical fiber having a grating provided at a predetermined position in the core), and a tip portion of the optical filter. A ferrule attached to the optical filter in a state where at least a part thereof is housed in the through hole, and (b) at least a portion of the tip portion of the optical filter which is not housed in the through hole of the ferrule is housed. And a holding part to which one end of the ferrule is attached. It should be noted that this plug may be configured only with a ferrule (see FIG. 2 or FIG. 3).

In the first embodiment, the filter area of the optical filter provided with the grating is
It is located in a portion of the tip portion of the optical filter which is not housed in the through hole of the ferrule and is housed in the hollow portion of the flange (see FIG. 6). On the other hand, in the second embodiment, the filter area of the optical filter provided with the grating is
Located in the part housed in the through hole of the ferrule (Fig. 1
8 etc.). In the optical connector according to the present invention, when the filter area 122 provided with the grating is arranged so as to straddle the storage space of the ferrule and the storage space of the flange 24, a sufficient filter function cannot be obtained, so that the filter of the optical filter is not obtained. The entire region is housed either in the through hole of the ferrule or outside the ferrule and in the housing space of the flange.

As shown in FIG. 6, in the first embodiment, as the first light shielding structure, the tip portion 121 (the portion where the coating is removed) of the optical filter 12 in the plug 1 is provided. Filter region 122 located at
In the space defined by the outer peripheral surface of the flange 24 and the inner wall of the hollow portion 242 of the flange 24.
3 has a refractive index substantially equal to or higher than that of the clad 124 of the optical filter 12).

Further, as shown in FIG. 12, in the first embodiment, as the second light shielding structure, in the plug 1, the outer peripheral surface of the filter region 122 of the optical filter 12 and the flange 24 are provided. A tubular member 250 surrounding the filter region 122 in a state defined by the inner wall of the hollow portion 242 with the optical filter 12 penetrating (whether the tubular member 250 is substantially the same as the cladding 124 of the optical filter 12 or not). (Having a higher refractive index) is stored. In the second light shielding structure, at least the outer peripheral surface of the filter region 122 of the optical filter 12 and the tubular member 2
In the space defined by the inner wall of 50, the desired adhesive 2
51 (this adhesive 251 is the clad 1 of the optical filter 12
24, which has a refractive index substantially equal to or higher than that of 24).

Further, as shown in FIG. 14, in the first embodiment, as the third light shielding structure, at least the optical filter 12 among the optical filters 12 in the hollow portion 242 of the plug 1 is provided. A coating 115 that surrounds the grating 126 is provided on the outer peripheral surface of the filter region 122. In addition, in this third light shielding structure,
The coating 115 is the clad 124 of the optical filter 12.
Has a refractive index substantially equal to or higher than.

Next, in the second embodiment of the present invention,
The light shielding structure can also be realized by configuring the ferrule 13A with a transmissive material that transmits light having a wavelength matching the reflection wavelength of the grating 126 (fourth light shielding structure). This transmissive material also has a refractive index substantially equal to or higher than that of the cladding 124 of the optical filter 12, and FIG. 18 shows a sectional structure of the optical connector having the fourth light shielding structure. ing.

Further, in the second embodiment, the ferrule 13B has a reflection wavelength of the grating 126 in a region of the light to be reflected by the grating 126, where the light emitted from the grating 126 to the cladding 124 reaches. You may further provide the light absorption structure for absorbing the light which has a wavelength which corresponds to (5th light shielding structure). This fifth light-shielding structure has, for example, a configuration similar to that shown in FIG. 18, and the ferrule 13B is made of a light-absorbing material that absorbs light having a wavelength matching the reflection wavelength of the grating 126. realizable. On the other hand, in the fifth light shielding structure, as shown in FIG. 22, the inner wall of the through hole 130 of the ferrule 13C has a light absorbing layer made of a material that absorbs light having a wavelength matching the reflection wavelength of the grating 130. It can also be realized by forming 135.

Further, as shown in FIG. 24, in the second embodiment, the optical filter 1 is used as a sixth light shielding structure.
Of the tip portion 121 of 2c, the ferrule 13 (see FIG.
Even if the outer diameter of a predetermined portion of the portion housed in the through hole 130 of 5) where the light to be reflected by the grating 126 reaches is smaller than the outer diameter of the remaining portion of the optical filter 12c. Good. In this case, in the space defined by the outer peripheral surface of the predetermined portion of the optical filter 12c and the inner wall of the through hole 130 of the ferrule 13, the light absorbing material 1 that absorbs the light having the reflection wavelength of the grating 126 is absorbed.
36 is filled (see FIG. 26). It should be noted that this light absorbing material 136 is also the clad 124 of the optical filter 12c.
Has a refractive index substantially equal to or higher than.

As shown in FIGS. 29 to 34, in the second embodiment, the plug (particularly,
The ferrule may be provided with a structure for limiting the light emission opening at one end face 125 of the optical filter 12 to be smaller than the cross section perpendicular to the optical axis of the optical filter 12.

Specifically, the seventh light-shielding structure has the grating 12 in the tip portion 121 of the optical filter 12 housed in the through hole 130 of the ferrule 13.
6, a first light shielding member having an opening of the through hole 130 of the ferrule 13 located on the one end face side of the optical filter 12 and having an opening smaller than the one end face 125 of the optical filter 12. It can be realized by covering with 140 (see FIG. 29).

In the seventh light-shielding structure, the first opening of the through hole 130 provided in the ferrule 13D, which is located on the one end face side of the optical filter 12 with respect to the grating 126, is provided with the grating. The second opening of the through hole 130 of the ferrule 13D, which is located on the side opposite to the first opening with respect to 126, is made smaller than the second opening.
A protrusion 141 may be provided in the opening (see FIG. 31).

Further, the seventh light-shielding structure has the optical filter 1 housed in the through hole 130 of the ferrule 13.
This can also be realized by attaching the second light shielding member 142 having an opening smaller than the size of the cross section of the optical filter 12 to the one end face 125 of No. 2 (see FIG. 33). The second light shielding member 142 is housed in the through hole 130 of the ferrule 13.

In each of the above-mentioned seventh light-shielding structures, the diameter of the one end face 125 of the optical filter 12 is set to the mode field diameter of light propagating in the optical filter 1.
It is preferable to limit the size to be larger than 14 times and smaller than the outer diameter of the clad 124 of the optical filter 12.

As shown in FIGS. 35 to 47, in the second embodiment, the ferrule is used as the eighth light shielding structure.
On the outer peripheral surface of the tip portion 121 of the optical filter 12 housed in the through hole 130 of the ferrule, a region of the light to be reflected by the grating 126, which light emitted from the grating 126 to the cladding 124 reaches. You may provide the structure for exposing.

Specifically, the eighth light-shielding structure has a notch 190 (see FIG. 35) extending from the outer peripheral surface of the ferrule 13E to the through hole 130 accommodating the optical filter 12, or the outside of the ferrule 13F. It can also be realized by providing a through hole 191 that connects the inner wall of the through hole 130 accommodating the tip portion 121 of the optical filter 12 from the side surface (see FIG. 42). Further, in this configuration, the exposed region of the tip portion 121 of the optical filter 12 housed in the through hole 130 of the ferrules 13E and 13F is substantially the same as or larger than the clad 124 of the optical filter 12. It is preferably covered with a refractive index matching material 700 having a refractive index.

Further, as shown in FIG. 48, in the second embodiment, the ferrule 13 is used as the ninth light shielding structure.
The grating 126 located in the through hole 130 of the
The filter region 122 of the optical filter 12 in which the
May be separated from the end surface 125 of the tip portion 121 of the optical filter 12 by 3 mm or more.

Next, as shown in FIGS. 54 to 57, in the second embodiment, as a tenth light shielding structure, the ferrule 13 is formed on the inner wall of the through hole 130 of the ferrule 13G.
The enlarged portion 134a having a larger cross section than the cross section near the end surface 131 of G may be provided. In this configuration, the enlarged portion 134a is located in a region where the light emitted from the grating 126 to the cladding 124 of the light to be reflected by the grating 126 reaches, and the tip portion 121 of the optical filter 12 has the ferrule. When accommodated in the through hole 130 of 13G, a gap 135a is formed by the enlarged portion 134a and the outer peripheral surface of the optical filter 12.

Further, as shown in FIGS. 58 to 70, in the second embodiment, as the eleventh light shielding structure, the light to be reflected by the grating 126 is emitted from the grating 126 to the clad 124. A groove may be provided in a region where light reaches and a space may be provided between the outer peripheral surface of the optical filter 12 and the through hole 130 of the ferrule.

In the eleventh light shielding structure, the groove provided on the inner wall of the through hole of the ferrule is the groove 135 shown in FIG.
As indicated by b, it extends from the first end of the ferrule 13H along the central axis of the through hole 130 toward the second end (including the end surface 131) facing the first end. It may have a shape. Further, like the groove 135c in FIG. 62, a groove provided on the inner wall of the through hole 130 of the ferrule 13I may be formed along the circumferential direction perpendicular to the central axis of the through hole 130. Further, like the groove 135d of FIG. 67, the groove provided on the inner wall of the through hole 130 of the ferrule 13J is located at the first end of the ferrule 13J from the first end with respect to the central axis of the through hole 130. Second opposite the end of the
The shape may extend spirally toward the end portion (including the end surface 131) of.

In the eleventh light-shielding structure, provided on the outer peripheral surface of the tip portion 121 of the optical filter 12 housed in the through hole 130 of the ferrules 13H to 13J and the inner wall of the through hole 130. The grooves 135b-13
The space defined by 5d is more preferably filled with a refractive index matching material 800 having a refractive index substantially equal to or higher than that of the cladding 124 of the optical filter 12. In addition, in the eleventh light shielding structure, the grooves 135b to 135d are formed.
Of the inner wall of the through hole 130 of the ferrules 13H to 13J is located on the end face side of the tip portion 121 of the optical filter 12 with respect to at least the filter region 122 of the optical filter 12 provided with the grating 126.
The ferrules 13H to 13J are provided in a region excluding the ends (including the end face 131).

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION An optical connector according to the present invention will be described below with reference to FIGS.

The optical connector according to the present invention has at least the basic structure shown in FIGS. For example, FIG. 1 shows an optical connector for optically coupling between the optical fiber cables 11a and 11b each having a single optical fiber 12a and 12b and a plastic coating. In the optical connector of FIG. 1, the tip portion of one optical fiber cable 11a (optical fiber 12a
Is exposed), and the plug 1 is attached. The plug 1 includes a ferrule 13a attached to the tip of the optical fiber cable 11a, and the ferrule 1
A flange holding one end of 3a (see FIGS. 4 and 5), the ferrule 13a and a cover 14a for protecting the flange.
It has. Also, the other optical fiber cable 11
The plug 1 is also attached to the tip portion of b (including the portion where the optical fiber 12b is exposed). Plug 1 attached to the other optical fiber cable 11b
, Ferrule 13b, flange (see FIGS. 4 and 5),
And a cover 14b. The one and the other optical fiber cables 11a and 11b are optically coupled via the adapter 2 in which the alignment sleeve 21 is housed. At this time, a part of the ferrules 13a and 13b is housed in the alignment sleeve 21 in the adapter 2.

In this specification, an optical fiber
The cable (optical cord) is not only a cable (cord) in which a single optical fiber is plastic-coated, but also a ribbon-type cable (cord) 15a in which a plurality of optical fibers 16a and 16b are integrally plastic-coated, 15b is also included (see FIG. 2).
FIG. 2 shows an optical connector for optically coupling optical fiber cables 15a, 15b that respectively include a plurality of optical fibers 16a, 16b. The plug 1 is attached to a tip portion (including a portion where the optical fiber 16a is exposed) of one optical fiber cable 15a. This plug 1 is provided with a ferrule 17a having a guide pin hole 18a provided along the optical fiber 16a and a guide pin 19a provided on the end face. Further, the ferrule 17b (included in the plug) is attached to the tip portion of the other optical fiber cable 15b (including the portion where the optical fiber 16b is exposed). This ferrule 17b is also provided with a guide pin hole 18b along the optical fiber 16b and a guide pin 19b on its end face. These ferrules 17a and 17b have one guide pin hole 18a.
And the other guide pin 19b are engaged with each other, and the other guide pin hole 18b and the one guide pin hole 19a are engaged with each other, whereby the respective optical fiber cables 15a, 15
b is optically coupled.

The plug 1 is an optical fiber cable 1
The optical connector 10 with a cord is called because it may be sold by itself in a state where it is attached to the tip of 1a, 11b (or 15a, 15b). The optical connector according to the present invention also includes this optical connector with a cord 10.

As shown in FIG. 1 or 2, the optical connector 10 (including an optical connector with a cord) as described above not only optically couples the optical transmission lines but also connects the transmission lines and the optical elements. It also enables optical coupling. FIG. 3 shows a configuration example in which the optical connector (optical connector with a cord) according to the present invention is connected to the optical module 20. That is, the ferrule 24 attached to the tip portion of the optical fiber cable 11 (including the portion where the optical fiber 23 is exposed).
The (included in the plug 1) is housed in the sleeve 20 a of the optical module 20. The optical module 20 is composed of the sleeve 20a, a stem 20c having an optical element 20d such as a light receiving element mounted on its main surface, and a holder 20b for holding the optical element at a predetermined position.

Next, a basic assembling process of the optical connector according to the present invention will be described with reference to FIG.

First, a waveguide structure in which a core having a predetermined refractive index is covered with a clad having a refractive index lower than that of the core is provided, and the waveguide structure is provided at a predetermined position in the core along the longitudinal direction (of the propagating light). An optical fiber cable 1 having a grating whose refractive index changes periodically (along the traveling direction)
1 (including an optical filter) is prepared. This optical fiber
The cable is an optical fiber 1 with a grating.
The outer peripheral surface of 2 (hereinafter referred to as an optical filter) is coated. Particularly, in a typical configuration of the optical filter 12 of the optical connector according to the present invention, the coating on the tip portion 121 is removed and the region where the grating is formed is called a filter region 122.

The optical filter 12 includes a cover 14,
Holding part 24 for holding the hollow part 242 and the ferrule 13
The front end portion 121 of the ferrule 13 is inserted into the through hole 130 of the ferrule 13 which penetrates the flange 24 having the number 1 and the coating is removed. Then, with the ferrule 13 attached to the tip portion 121 of the optical filter 12, the ferrule 13 is adjusted so that the end surface 125 (see FIG. 6) of the optical filter 12 and the first end surface 131 of the ferrule 13 are aligned. The first end surface 131 of is polished. In addition,
The through hole 130 has an inner diameter substantially the same as the diameter of the optical filter 12. In this specification, “substantially the same” means that the optical filter 12 can be appropriately held.
Means that the inner diameter of the through hole 130 is the same as the inner diameter of the through hole 130.

Thereafter, the ferrule 13 is fixed to the flange 24 with the second end surface 132 side of the ferrule 13 attached to the optical filter 12 being housed in the holding portion 241 of the flange 24. Thereby, the optical connector as shown in FIG. 5 is obtained. The overall basic structure of the optical connector of FIG. 5 is a structure common to the optical connectors described below, and this FIG. 5 will be referred to as necessary in the following description of the optical connector according to the present invention. Will be referenced each time.

Next, each embodiment of the optical connector according to the present invention will be described. The optical connector according to the present invention has the following two embodiments depending on the position of the housed grating.

That is, the tip portion 12 of the optical filter 12
1 is attached to the optical filter (for example,
A through hole for accommodating a part of the optical fiber with a grating provided at a predetermined position in the core),
A ferrule 13 attached to the tip portion of the optical filter 12 in a state where at least a part of the tip portion 121 of the optical filter 12 is accommodated in the through hole, and an end portion (including an end face 132) of the ferrule 13 is attached. A flange 24 having a holding portion 241 and at least the ferrule 1 of the tip portion 121 of the optical filter 12.
3 has a hollow portion 242 for accommodating a portion not accommodated in the through hole 130. Then, in the first embodiment, the filter area 121 of the optical filter 12 provided with the grating 126 is
It is located in a portion of the tip portion 121 of the optical filter 12 which is not housed in the through hole 130 of the ferrule 13 but is housed in the hollow portion 242 of the flange 24. In addition, in the second embodiment, the grating 12
Filter region 12 of the optical filter 12 provided with 6
No. 1 is located in a portion of the tip portion 121 of the optical filter 12, which is housed in the through hole 130 of the ferrule 13.

In the optical connector according to the present invention, when the filter region 122 provided with the grating 126 is arranged so as to straddle the storage space of the ferrule 13 and the storage space of the flange 24, a sufficient filter function cannot be obtained. In other words, the stress applied to a part of the filter region 122 housed in the ferrule 13 mainly depends on the linear expansion coefficient of the ferrule 13, while the remaining stress contained in the hollow portion of the flange 24. The stress applied to the area depends on the coating, filler (adhesive), flange 24
, Etc., depending on the linear expansion coefficient of the member covering the remaining area. Therefore, when each part of the filter region 122 is covered with a member having a different linear expansion coefficient, the stress distribution in the longitudinal direction in the filter region 122 cannot be made uniform. Therefore, in order to make the stress distribution in the longitudinal direction uniform in the filter region 122, in the optical connector according to the present invention, the filter region 12 of the optical filter 12 is
The whole 2 is stored either in the through hole 130 of the ferrule 13 or outside the ferrule 13 and in the storage space of the flange 24.

In particular, the optical connector according to the present invention is a part of the light to be reflected by the grating, which is the light emitted from the grating to the clad, and the optical filter from the filter region of the optical filter provided with the grating. A light-shielding structure for preventing the propagation of light propagating through the clad toward the one end face is provided. Hereinafter, the respective light-shielding structures will be described with reference to FIGS. A description will be given using 70.

In this specification, the term "waveguide" means
A circuit or line for confining and transmitting a signal light of a predetermined wavelength in a certain region by utilizing the difference in refractive index between the core and the clad, which includes an optical fiber and a thin film waveguide.

(First Embodiment) The first light shielding structure of the optical connector according to the first embodiment will be described below.

FIG. 6 is a side sectional view showing the structure of the optical connector according to the present invention having the first light shielding structure (A- in FIG. 5).
7 is a cross-sectional view taken along line A), and FIG. 7 is a cross-sectional view (B of FIG. 5) of the optical connector in a portion indicated by an arrow B1 of FIG.
-Corresponding to a sectional view taken along line B). This optical connector includes an optical filter 12 obtained by forming a grating 126 on a single mode optical fiber having a core 123 and a clad 124, and the optical filter 12.
13 for housing the tip of the
And a flange 24 having a holding portion 241 to which one end of the ferrule 13 is attached.

The optical filter 12 is premised to be used in an inspection system of an optical communication network using an OTDR device. In the optical line that constitutes the optical communication network, the signal light for optical communication is transmitted from the station building to the subscriber terminal device, and the inspection light from the OTDR device is transmitted to inspect the state of the optical line. To be done. As the inspection light, light having a wavelength different from that of the signal light is used, but when the inspection light enters the subscriber terminal device, it is not preferable because it becomes noise of the signal light. Therefore, it is necessary to provide an optical filter for blocking the inspection light in the optical line. The optical filter 12 meets such a need, and the inspection light is provided to the subscriber terminal by providing a grating 126 for reflecting the inspection light of a predetermined wavelength on the core 123 of the optical fiber forming a part of the optical line. It is designed to be cut off when viewed from the side.

Both the core 123 and the clad 124 of the optical filter 12 are mainly made of quartz (SiO ₂ ) glass, while the clad 124 is composed of substantially pure quartz glass. GeO ₂ which is a refractive index raising material is added to the quartz glass constituting the. As a result, the refractive index of the core 123 is equal to that of the clad 1.
24, the relative refractive index difference between the core 123 and the cladding 124 is about 0.35%.

The grating 126 is a region in the core 123 in which the effective refractive index changes periodically between the minimum refractive index and the maximum refractive index along the optical axis longitudinal direction of the optical filter 12. In other words, the grating 126 is a region having a refractive index distribution such that the effective refractive index repeatedly changes along the optical axis between the minimum refractive index and the maximum refractive index. The grating 126 reflects light having a reflection wavelength over a relatively narrow wavelength range centered on the reflection wavelength (Bragg wavelength) determined by the period of refractive index change, that is, the grating period (also referred to as grating pitch). This reflection wavelength substantially matches the wavelength of the inspection light.

The grating 126 can be formed by utilizing the phenomenon that when the quartz glass containing germanium is irradiated with ultraviolet light, the refractive index of the irradiated portion increases by an amount corresponding to the intensity of ultraviolet light. That is, the clad 12
Core 123 to which germanium is added from the surface of 4
When the ultraviolet light on which the interference fringes of a predetermined pitch are formed is radiated toward, the refractive index distribution according to the light intensity distribution of the interference fringes is formed in the ultraviolet light irradiation region of the core 123. The region having the refractive index distribution formed in this manner is the grating 126. In this case, the minimum refractive index of the grating forming portion is substantially equal to the initial effective refractive index of the core 123 (effective refractive index before ultraviolet light irradiation).

A reference numeral 115 in FIG. 6 is a UV cut resin coating for covering the surface of the clad 124 and has a role of protecting the core 123 and the clad 124. The resin coating 115 is removed at the tip of the waveguide type optical fiber 20 because the core 123 is irradiated with ultraviolet light when the grating 126 is manufactured as described above.

The ferrule 13 is a zirconia tubular member that surrounds the tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed. Through hole 1 of ferrule 13
The inner diameter of 30 is 0.126 mm, and its inner surface is a mirror surface.

The flange 24 is a tubular holding member in which the rear end of the ferrule 13 is attached to the holding portion 241. The hollow portion 242 of the flange 24 has an inner diameter of 1 mm, and the hollow portion 242 of the flange 24 has an inner diameter of 1 mm.
A part (filter region 122) including the grating 126 is housed therein. Hollow part 24 of flange 24
An adhesive 243 is filled between the optical filter 12 and the flange 24 inside the optical filter 2, and the optical filter 12 is fixed in the flange 24 by the adhesive 243. A resin adhesive having a refractive index substantially the same as that of the clad 124 is used as the adhesive 243.

The optical connector according to the present invention is characterized in that the grating 126 is arranged in the hollow portion 242 of the flange 24. As a result, of the light of the reflection wavelength of the grating 126, the grating 126
The light radiated from the cladding to the clad 124 is reduced and the light blocking rate is increased.

In the following, first, the core 1 of the optical filter 12 will be described.
Clad 1 from grating 126 formed in 23
It will be described that light is radiated toward 24 and that the light blocking rate of the optical filter 12 is thereby reduced. The inventors confirmed the above facts by conducting an experiment using the device shown in FIG. This experimental apparatus is an apparatus for investigating that light having a reflection wavelength of the grating 116 is emitted from the grating 116 formed in the core of the optical fiber 100 toward the cladding. The optical fiber 100 on which the grating 116 is formed is equivalent to an optical fiber type optical filter. Like the optical filter 12 of this embodiment, the optical fiber 100 is a silica glass single mode fiber in which germanium is added to the core. Grating 116
Has a length of 10 mm and a constant grating pitch, and its reflection wavelength is about 1554 nm. The clad of the optical fiber 100 is covered with a resin material except for both ends thereof. The one end where the resin coating is removed is connected to the SLD200 (Super Lumine
scent Diode). This SLD200
Is a semiconductor light emitting element that outputs light in a predetermined wavelength range including the reflection wavelength of the grating 116. The other end from which the resin coating has been removed is connected to the spectrum analyzer 300 via the fiber adapter 310. The grating 116 is separated by a distance d from the end face on the spectrum analyzer 300 side in the portion of the optical fiber 100 where the resin coating is removed.

The inventors of the present invention made the SLD 200 emit light to inject the inspection light into the optical fiber 100, and the spectrum of the light transmitted through the portion where the grating 116 was formed was d = 21 mm (see FIG. 9). , D = 500m
In each case of m (see FIG. 10), detection was performed by the spectrum analyzer 300. 9 and 10
[Fig. 3] is a diagram showing respective detection results. 9 and 1
The peaks 400 and 410 of decreasing the amount of transmitted light due to light reflection on the grating 116 appear on both of 0, but d =
The decrease peak 400 at 21 mm is d = 500 mm
In this case, the peak height is greatly reduced compared to the reduced peak 410. That is, the amount of transmission attenuation of light having a wavelength to be blocked by the grating 116 is lower when d = 21 mm than when d = 500 mm.
Since the grating 116 is the same when d = 21 mm and when d = 500 mm, this difference in the transmission attenuation amount is not caused by the reflectance of the grating 116,
From the grating 116 to the spectrum analyzer 300
This is due to the difference in the distance to.

Considering this, the difference in the transmission attenuation amount can be understood as follows. Since the grating 116 includes a portion where the refractive index is locally increased, a mode field mismatch occurs between the grating formation portion and other portions. When the light of the reflected wavelength of the grating reaches the grating, a part of it travels in the grating while being reflected, but at this time, due to the mismatch of the above mode fields, it is emitted from each part of the grating to the cladding. Light is generated.

FIG. 11 is a diagram showing the behavior of light emitted from the grating 116 to the cladding. In this figure, reference numeral 112 is the core of the optical fiber 100, and reference numeral 11
Reference numeral 4 represents a clad. Then, what is denoted by reference numeral 120 is light emitted from the grating 116 to the cladding 114. As shown in FIG. 11, such light travels in the region composed of the clad 114 and the core 112 and reaches the front of the grating 116. Unlike the core 112, the region formed by the clad 114 and the core 112 has a weaker light confining effect.
The light emitted from the grating 116 has a relatively large power attenuation as it travels. Therefore, as shown in the above experimental results, the grating 116
The greater the distance from the spectrum analyzer 300 to the spectrum analyzer 300, the less the light of the reflection wavelength detected by the spectrum analyzer 300, and the higher the peak of decrease in the amount of transmitted light.

Usually, the ferrule of the optical connector is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, when the tip portion including the grating 116 of the optical fiber 100, which is an optical filter, is housed in the ferrule, the light emitted from the grating 116 and emitted from the clad 114 is reflected on the inner surface of the ferrule and returns to the clad 114 again. Since the light travels in front of the grating 116, the light is not always sufficiently blocked by the optical filter having the waveguide structure.

The optical connector according to the present invention was devised in view of such a fact. That is, in the optical connector of FIG. 6, a portion of the optical fiber type optical filter 12 including the grating 126 (filter region 12
2) is accommodated in the hollow portion 242 of the flange 24.
The adhesive 243 does not have high reflectivity like the ferrule 13, so that the light from the grating 126 out of the light having a wavelength matching the reflection wavelength of the grating 126 (light to be reflected by the grating 126) is clad with the cladding 1.
The light radiated to 24 proceeds while leaking to the adhesive 243 around the clad 124. After that, the light emitted from the grating 126 is emitted by the optical filter 1.
Of the light emitted from the grating 126, the light component that reaches the portion of the ferrule 13 accommodated in the through hole 130 of the ferrule 13 but leaks into the adhesive 243 is blocked by the end surface 132 of the ferrule 13, and You cannot move forward any further. This reduces the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the grating 126, so that the optical connector of FIG. A light component that has not been reflected (hereinafter referred to as radiated light) can be blocked (first light shielding structure).

Further, in the optical connector of FIG. 6, since the adhesive 243 having a refractive index substantially the same as that of the clad 124 is filled between the optical filter 12 and the flange 24,
Light emitted from the grating 126 is hardly reflected on the outer surface of the clad 124. As a result, the emitted light from the grating 126 spreads to the adhesive 243 very easily, and the emitted light can be blocked at a high rate.

Next, the second light shielding structure of the optical connector of the first embodiment will be described.

FIG. 12 is a side sectional view showing the structure of the optical connector according to the present invention having the second light shielding structure (A in FIG. 5).
-Corresponding to the cross-sectional view along line A). FIG.
FIG. 6 is a cross-sectional view (corresponding to the cross-sectional view taken along the line BB of FIG. 5) of the optical connector in the portion indicated by the arrow B2 in FIG. In this optical connector, a tubular member 250 that surrounds the outer periphery of the clad 124 of the optical filter 12 is arranged between the distal end portion 121 of the optical filter 12 from which the coating 115 has been removed and the hollow portion 242 of the flange 24. . This tubular member 250
Has an inner diameter of 0.14 mm, and the tip portion 121 of the optical filter 12 penetrates the tubular member 250. And
The grating 126 is located within the tubular member 250. An adhesive 251 is interposed between the optical filter 12 and the tubular member 250, and the tubular member 250 is fixed to the outer periphery of the optical filter 12 by this adhesive 251. In addition, the tubular member 250 and the hollow portion 24 of the flange 24
An adhesive 251 is also interposed between the two and the tubular member 250 is fixed to the inner surface of the hollow portion 242 of the flange 24 by the adhesive 251. The adhesive 251 has substantially the same refractive index as that of the clad 124 of the optical filter 12, and the tubular member 250 has the adhesive 251 and the clad 1.
It has the same refractive index as 24.

In the optical connector shown in FIG. 12, the leak light component emitted from the grating 126 to the clad 124 out of the light of the reflection wavelength of the grating 126 is adhesive 25.
1 and the tubular member 250 will leak and proceed. In particular, in the optical connector of FIG. 12, since the adhesive 251 and the tubular member 250 have substantially the same refractive index as the clad 124, the radiated light (leakage light component) from the grating 126 is the adhesive 251 and the tubular member. Spreads up to 250 very easily. After this, grating 1
The emitted light from 26 is the ferrule 1 of the optical filter 12.
Although it reaches the portion housed in No. 3, the leaked light component distributed at least in the adhesive 251 and the tubular member 250 of the radiated light from the grating 126 is blocked by the ferrule 13 and proceeds further forward. You cannot do it. As a result, the power of the emitted light emitted to the clad 124 out of the light of the reflected wavelength of the grating 126 is reduced, so that the optical connector of FIG. 12 can block the emitted light from the grating at an extremely high rate.

Further, in the second light-shielding structure, the tubular member 250 is arranged in the hollow portion 242 instead of filling the entire hollow portion 242 of the flange 24 with the adhesive 243. The amount is smaller than in the case of the first light shielding structure. As a result, when the adhesive 243 cures, the adhesive 243 contracts and exerts stress on the grating 126.
The phenomenon that the characteristics of No. 6 are changed is prevented, and the optical connector of FIG. 12 can surely exhibit the desired filter function.

Next, the third light shielding structure of the optical connector of the first embodiment will be described.

FIG. 14 is a side sectional view showing the structure of the optical connector according to the present invention having the third light-shielding structure (A in FIG. 5).
-Corresponding to the cross-sectional view along line A). FIG.
6 is a cross-sectional view (corresponding to the cross-sectional view taken along the line BB of FIG. 5) of the optical connector of a portion indicated by an arrow B3 in FIG. The optical connector of FIG. 14 differs from the optical connector of FIG. 6 in the configuration of the optical filter cable 11 housed therein. That is, the optical filter cable 11 of FIG.
A UV cut resin coating 115 is provided around the filter region 122 including 26. This optical filter cable 11 is a coating 11 for a predetermined portion of a base optical fiber.
After removing 5 and irradiating this portion with ultraviolet interference fringes to form a grating 126, the portion is covered again 11
5 is re-formed. Note that this coating 115
Has substantially the same refractive index as the cladding 124 of the optical filter 12.

An adhesive 243 is filled between the optical filter 12 of FIG. 14 and the hollow portion 242 of the flange 24, whereby the optical filter 12 is fixed in the hollow portion 242. The adhesive 243 is used for the clad 12
4 and the coating 115 have substantially the same refractive index.

In the optical connector of FIG. 14, of the light of the reflection wavelength of the grating 126, the emitted light emitted from the grating 126 to the clad 124 proceeds while leaking to the coating 115 and the adhesive 243. Particularly, in the third light shielding structure, the coating 115 and the adhesive 243 are used.
Has substantially the same refractive index as the cladding 124,
The emitted light from the grating 126 spreads very easily to the coating 115 and the adhesive 243. After that, the light emitted from the grating 126 is emitted by the optical filter 1.
Of the light emitted from the grating 126, the leaking light component propagating through the coating 115 and the adhesive 243 that reaches the portion of the No. 2 that is accommodated in the through hole 130 of the ferrule 13 is blocked by the ferrule 13, and You cannot move forward any further. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the grating 126 is reduced, so that the optical connector of FIG. 14 can block the emitted light at an extremely high rate.

Further, in the third light-shielding structure, unlike the case of the first light-shielding structure, the coating 115 is formed around the filter region 122 of the optical filter 12, so that when the adhesive 243 is cured. The influence of the stress applied to the grating 126 due to the contraction of the adhesive 243 is reduced, and the characteristic variation of the grating 126 is reduced. Therefore, the optical connector of FIG. 14 having the third light shielding structure can surely exhibit the desired filter function.

(Second Embodiment) Next, the fourth light shielding structure of the optical connector of the second embodiment will be described.

FIG. 16 is a side sectional view of each member (a sectional view taken along the line AA in FIG. 5) showing a part of the assembling process of the optical connector according to the present invention having the fourth light shielding structure. 17 is a cross-sectional view (corresponding to the cross-sectional view taken along the line C-C in FIG. 5) of the optical connector in the portion indicated by the arrow C1 in FIG. This optical connector includes an optical fiber type optical filter 12 and other optical elements (optical fiber, semiconductor element, etc.).
The optical filter 12 can be housed in the optical filter 12. Specifically, the optical connector is
Through-hole 1 for accommodating the tip portion 121 of the optical filter 12
Ferrule 13A having 30 and this ferrule 13
The flange 2 in which the rear end portion of A is attached to the holding portion 241
And 4.

Next, referring to FIGS. 16 and 17,
The fourth light shielding structure of the optical connector according to the present invention will be described. The ferrule 13A is a member for surrounding and holding the tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed. A through hole 130 extending along the central axis of the ferrule 13A is provided at the center of the ferrule 13A, and the above-mentioned tip portion 121 of the optical filter 12 is inserted into this through hole 130.
The flange 24 is a tubular holding member in which the rear end of the ferrule 13A is attached to the holding portion 241. The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 covered with the resin coating 115. It has become so.

As the fourth light-shielding structure, in the optical connector shown in FIG. 16, the ferrule 13A is made of a light transmitting material that transmits light having the reflection wavelength of the grating 126. As a result, the optical filter 12 is added to the optical connector of FIG.
Of the reflection wavelength of the grating 126, unnecessary emission light emitted from the grating 126 to the cladding 124 is transmitted through the ferrule 13A and emitted to the outside. As a result, the light blocking rate of the optical filter 12 is increased. Will increase. Various materials can be used as the above-mentioned light transmitting material, and it is more preferable that the light having the reflection wavelength of the grating 126 is transmitted at a high rate.
Optical glass such as quartz glass is suitable as a specific example of the light transmitting material.

In the conventional optical connector, the ferrule is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, as can be seen from the experiments described with reference to FIGS. 8 to 11, when the tip portion including the grating 116 of the optical fiber 100 that is the optical filter is housed in the ferrule, the grating 11
The light emitted from 6 and emitted from the clad 114 is reflected on the inner surface of the ferrule and returns to the clad 114 again.
Since the light travels in front of the grating 116, the light is not necessarily sufficiently blocked by the optical filter.

The fourth light-shielding structure of the optical connector according to the present invention was devised in view of such a fact.
That is, in the optical connector having the fourth light-shielding structure, when the optical filter 12 is accommodated, the light having the reflection wavelength of the grating 126 is emitted from the grating 126 to the clad 124 and reaches the outer surface of the clad 124. The light emitted from 124 also passes through the ferrule 13A and is emitted to the outside. Therefore, the leaked light component radiated from the grating 126 to the clad 124 is emitted from the clad 124, is reflected by the inner surface of the ferrule 13A, returns to the inside of the optical filter 12, and travels in front of the grating 126. Such a phenomenon is unlikely to occur. As a result, the grating 12
Since the power of the leaked light component of the light of the six reflected wavelengths that is emitted to the clad 124 and passes through the filter region 122 is reduced, the optical connector having the fourth light shielding structure is
The light blocking rate of the optical filter 12 will be increased.

If the light-transmitting material forming the ferrule 13A has a refractive index substantially matching the surface layer of the clad 124 of the optical filter 12, the optical filter 12 is housed in the optical connector (inside the ferrule 13A). In this case, the emitted light from the grating 126 is hardly reflected at the interface between the optical filter 12 and the ferrule 13A. Therefore, the light emitted from the grating 126 can be transmitted through the ferrule 13A very efficiently, and the light blocking rate of the optical filter 12 can be extremely increased.

If the light transmitting material forming the ferrule 13A has a refractive index higher than that of the surface layer of the clad 124 of the optical filter 12, the optical filter 1 is inserted in the plug.
When 2 is accommodated, the emitted light from the grating 126 is less likely to be totally reflected at the interface between the optical filter 12 and the ferrule 13A. Therefore, the light emitted from the grating 126 can be efficiently transmitted through the ferrule 13A, and the light blocking rate of the optical filter 12 can be greatly increased.

FIG. 18 is a side sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) showing the optical connector obtained through the assembling process of FIG. 19 is a cross-sectional view of the portion of the optical connector indicated by the arrow C2 in FIG. 18 (C in FIG. 5).
It corresponds to a cross-sectional view taken along the line C). Optical filter 12
The ferrule 1 is the tip 121 with the resin coating removed.
It is inserted into the through hole 130 of 3A, and the grating 126 is also housed inside the through hole 130 of the ferrule 13A. The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 with the resin coating 115. An adhesive 255 is filled between the coating 115 of the optical filter 12 and the hollow portion 242 of the flange 24, and the optical filter 12 is fixed inside the hollow portion 242 of the flange 24 by the adhesive 255.

In the optical connector of FIG. 18, the grating 126 is radiated to the clad 124 and the clad 1 is emitted.
Of the light reaching the outer surface of 24, the leaked light component emitted to the outside of the clad 124 also passes through the ferrule 13A and is emitted to the outside. As a result, the grating 12
The power of unnecessary radiation light, which is radiated to the cladding 124 and passes through the filter region 122, of the light of the six reflected wavelengths is reduced. Therefore, the optical connector having the fourth light shielding structure has a high light blocking rate and can be suitably used as a constituent element of an inspection system of an optical line.

Next explained is the fifth light shielding structure of the optical connector according to the second embodiment of the invention.

As the fifth light-shielding structure, in the optical connector according to the present invention, the ferrule 13B has the grating 126.
It is composed of a light absorbing material that absorbs the light having the reflection wavelength (1st application example). In addition, the first of the fifth light shielding structure
Since the manufacturing and structure of the optical connector which is an application example is the same as the configuration of FIGS. 16 to 19 except for the ferrule 13B,
Hereinafter, the description of such a structure will be omitted. As a result, the fifth
In the optical connector adopting the first application example of the light shielding structure of
The ferrule 13B absorbs unnecessary radiation light radiated from the grating 126 to the cladding 124 among the light of the reflection wavelength of the grating 126, and as a result, the light blocking rate of the optical filter 12 is increased. Various materials can be used as the above-mentioned light absorbing material depending on the reflection wavelength of the grating 126.
The one that absorbs the light having the reflection wavelength of 6 at a high rate is more preferable. As an example, when the reflection wavelength is in the 1.3 μm band, the ferrule 13B may be formed using glass to which praseodymium which is a rare earth element is added. When the reflection wavelength is in the 1.55 μm band, The ferrule 13B may be made of glass or polyimide resin to which erbium which is a rare earth element is added.

In the conventional optical connector, the ferrule is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, as can be seen from the experiments described with reference to FIGS. 8 to 11, when the tip portion including the grating 116 of the optical fiber 100 that is the optical filter is housed in the ferrule, the grating 11
The light emitted from 6 and emitted from the clad 114 is reflected on the inner surface of the ferrule and returns to the clad 114 again.
Since the light travels in front of the grating 116, the light is not necessarily sufficiently blocked by the optical filter.

The optical connector according to the present invention having the fifth light shielding structure (first application example) is devised in view of such a fact. That is, the fifth light shielding structure (first
When the optical filter 12 is housed, the optical connector including the application example) is light having a reflection wavelength of the grating 126, emitted from the grating 126 to the cladding 124, reaches the outer surface of the cladding 124, and exits the cladding 124. The light is absorbed by the ferrule 13B. Therefore, the light radiated from the grating 126 to the clad 124 is emitted from the clad 124, is reflected by the inner surface of the through hole 130 of the ferrule 13B, and returns to the inside of the optical filter 12 again.
The phenomenon of progressing ahead of 26 is suppressed.
This reduces the power of unnecessary radiation light that is emitted to the cladding 124 and passes through the filter region 122 among the light of the reflection wavelength of the grating 126. As a result, the fifth light shielding structure (first application example) Therefore, the light blocking rate of the optical filter 12 is increased.

In the fifth light-shielding structure (first application example), if the light-absorbing material forming the ferrule 13B has a refractive index that is substantially the same as the surface layer of the clad 124 of the optical filter 12, the grating is formed. The emitted light from 126 is hardly reflected at the interface between the optical filter 12 and the ferrule 13B. Therefore, the light emitted from the grating 126 can be absorbed very efficiently by the ferrule 13B, and the light blocking rate of the optical filter 12 can be greatly increased.

In the fifth light-shielding structure (first application example), if the light-absorbing material forming the ferrule 13B has a higher refractive index than the surface layer of the clad 124 of the optical filter 12, the grating 126 is formed. It is difficult for the emitted light from the total reflection at the interface between the optical filter 12 and the ferrule 13B. Therefore, the light emitted from the grating 126 is efficiently absorbed by the ferrule 13B, and the light blocking rate of the optical filter 12 can be greatly increased.

An optical connector having a ferrule 13B made of a light absorbing material as the fifth light shielding structure (first application example) is the same as the structure of the optical connector having the fourth light shielding structure in FIGS. 18 and 19. is there. The tip portion 121 of the optical filter 12 from which the resin coating is removed is the through hole 1 of the ferrule 13B.
The grating 126 is also inserted into the through hole 130 of the ferrule 13. The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 with the resin coating 115. An adhesive agent 255 is filled between the coating 115 of the optical filter 12 and the hollow portion 242 of the flange 24.
Due to the optical filter 12, the hollow portion 242 of the flange 24 is
Is fixed inside.

In the optical connector having the fifth light-shielding structure (first application example), the light emitted from the grating 126 to the cladding 124 and reaching the outer surface of the cladding 124 is emitted to the outside of the cladding 124. The light is absorbed by the ferrule 13B. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced. Therefore, the optical connector with a built-in filter of the present embodiment has a high light blocking rate, and can be suitably used as a component of an optical line inspection system.

Next explained is the fifth light shielding structure (second application example) of the optical connector of the second embodiment according to the invention.

FIG. 20 shows a fifth light shielding structure (second application example).
FIG. 21 is a side sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) of each member showing a part of the assembly process of the optical connector provided with FIG. 21, and FIG. It is sectional drawing (corresponding to the sectional view along CC line of FIG. 5) of the optical connector of the part. This optical connector includes a ferrule 13C having a through hole 130 for accommodating the front end portion 121 of the optical filter 12, and a rear end portion of the ferrule 13C having a holding portion 24.
Flange 24 attached to 1 and ferrule 13C
Of the light absorption layer 135 formed on the inner surface of the through hole 130 of
It is composed of

The shape of the ferrule 13C is as shown in FIG.
6 to 19 is similar to the structure of the optical connector (including the fourth light shielding structure or the fifth light shielding structure (first application example)), but the material of the ferrule 13C has the structure of the first application example. Different from optical connector. That is, the material of the ferrule 13C is zirconia which has been conventionally used, and it is 1.3 μ which is often used as the inspection light wavelength of the optical line.
Since it efficiently reflects light in the m band and the 1.55 μm band, it is unsuitable as a light absorbing material constituting the ferrule 13B (first application example).

However, this fifth light shielding structure (second
In the optical connector including the application example, the light absorbing layer 135 is formed on the inner surface of the ferrule 13C, and this functions in the same manner as the ferrule 13B made of a light absorbing material. The light absorption layer 135 is composed of a light absorption material that reflects light having the reflection wavelength of the grating 126. As the light absorbing material, as described above, various materials can be used depending on the reflection wavelength of the grating 126. Since the light absorption layer 135 is formed on the inner wall of the through hole 130, the light absorption layer 135 itself has a pipe shape. The uncovered tip portion 121 of the optical filter 12 is inserted into the through hole 130 defined by the light absorbing layer 135, as shown in FIG.

When the optical filter 12 is housed in the optical connector (inside the ferrule 13C) equipped with the fifth light shielding structure (second application example), the light having the reflection wavelength of the grating 126 is emitted from the grating 126 to the clad 124. The light that reaches the outer surface of the clad 124 and exits the clad 124 is absorbed by the light absorption layer 135. Therefore, the phenomenon that the light emitted from the grating 126 to the clad 124 returns to the inside of the optical filter 12 after exiting the clad 124 and travels in front of the grating 126 is suppressed. As a result, the power of unnecessary radiated light that is emitted to the cladding 124 and passes through the filter region 122 among the light of the reflection wavelength of the grating 126 is reduced. Therefore, the optical connector of FIG. Similar to the optical connector with application example),
The light blocking rate of the optical filter 12 can be increased.

If the light-absorbing material forming the light-absorbing layer 135 has a refractive index that is substantially the same as the surface layer of the clad 124 of the optical filter 12, the light emitted from the grating 126 is emitted from the optical filter 12 and the light. Almost no reflection occurs at the interface with the absorption layer 135. Therefore, the light emitted from the grating 126 is absorbed very efficiently by the light absorption layer 135, and the light blocking rate of the optical filter 12 can be greatly increased.

If the light absorbing material forming the light absorbing layer 135 has a higher refractive index than the surface layer of the clad 124 of the optical filter 12, the light emitted from the grating 126 is absorbed by the optical filter 12 and the light absorbing material. Total reflection is less likely to occur at the interface with the layer 135. Therefore, the light emitted from the grating 126 can be efficiently absorbed by the light absorption layer 135, and the light blocking rate of the optical filter 12 can be greatly increased.

Next, FIG. 22 is a side sectional view (corresponding to the sectional view taken along the line AA in FIG. 5) showing the structure of the optical connector obtained through the assembly process shown in FIG. . FIG.
22 is a cross-sectional view of the optical filter indicated by the arrow C4 in FIG. 22 (corresponding to the cross-sectional view taken along the line CC of FIG. 5). This optical connector includes an optical filter 12 and the optical filter 12
13C for accommodating a ferrule and this ferrule 13C
And the flange 24 attached to the holding portion 241 thereof, and the outer surface of the clad 124 of the optical filter 12 is covered with the light absorption layer 135.

In the optical connector of FIG. 22, the light having the reflection wavelength of the grating 126, which is the light of the grating 12
Light radiated from 6 to the clad 124, reaching the outer surface of the clad 124 and exiting the clad 124
Absorbed by 35. As a result, the power of unnecessary radiation light that is emitted to the cladding 124 and passes through the filter region 122 among the light of the reflection wavelength of the grating 126 is reduced, so that the optical connector of FIG. It has a high light blocking rate similar to the optical connector having one application example).

Next explained is the sixth light shielding structure of the optical connector according to the second embodiment of the invention.

As shown in FIG. 24, the sixth light-shielding structure has a predetermined portion of the tip portion 121 of the optical filter 12c (a region where the light emitted from the grating 126 reaches).
It is realized by making the outer diameter D2 of (1) smaller than the outer diameter D1 (> D2) of other parts.

FIG. 25 is a side sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) of each member showing a part of the assembling process of the optical connector having the sixth light shielding structure. . As can be seen from FIG. 26, the tip portion 121 of the optical filter 12c is
Is inserted into the through hole 130 of the ferrule 13, a space is defined by the outer diameter D2 portion of the optical filter 12c (hereinafter referred to as a recess) and the inner wall of the through hole 130. The space is filled with a desired light absorbing material and the light absorbing portion 1
36 are formed.

FIG. 26 is a side sectional view (corresponding to the sectional view taken along the line AA in FIG. 5) showing the structure of the optical connector having the sixth light shielding structure. FIG. 27 is a cross-sectional view (corresponding to the cross-sectional view taken along the line CC of FIG. 5) of the optical connector of the portion shown by the arrow C5 in FIG. This optical connector is core 1
Optical fiber 12c in which a grating 126 is formed in a single mode optical fiber including a 23 and a clad 124, a ferrule 13 that accommodates a tip portion 121 of the optical filter 12c, and the ferrule 1
3 is composed of a flange 24 attached to the holding portion 242.

The optical filter 12c can be used, for example, in an inspection system of an optical communication network using an OTDR device.

As shown in FIG. 26, the optical filter 12
The clad 124 around the grating 126 of c
A light absorbing portion 136 is provided on the outer surface of the. The light absorbing portion 136 is formed by filling the concave portion formed on the outer surface of the clad 124 with a light absorbing material. This light absorbing material is a material that efficiently absorbs light having a reflection wavelength of the grating 126. As the light absorbing material, various materials can be used depending on the reflection wavelength, and it is more preferable that the light absorbing material absorbs light having the reflection wavelength of the grating 126 at a high rate. As an example, when the reflection wavelength is in the 1.3 μm band, glass containing praseodymium, which is a rare earth element, can be used, and the reflection wavelength is 1.55.
In the case of the μm band, glass or polyimide resin to which erbium which is a rare earth element is added can be used.

In FIG. 26, reference numeral 115 denotes a UV cut resin coating which covers the surface of the clad 124 and has a role of protecting the core 123 and the clad 124. The resin coating 115 is removed from the tip portion 121 of the optical filter 12c because the core 123 is irradiated with ultraviolet light when the grating 126 is manufactured as described above.

The ferrule 13 is a member having a through hole 130 for accommodating the tip portion 121 of the optical filter 12c from which the resin coating 115 has been removed. The tip portion 121 includes a grating 126. As described above, the clad 124 of the optical filter 12c and the ferrule 1
A light absorbing portion 136 is provided between the light absorbing portion 136 and the light receiving portion 3.

The flange 24 is a tubular holding member in which the rear end of the ferrule 13 is attached to the holding portion 241. The hollow portion 242 of the flange 24 accommodates the tip portion 121 of the optical filter 12c with the coating 115. The coating 115 and the flange 2 of the optical filter 12c
An adhesive 255 is filled between the hollow portion 4 and the hollow portion 4.
The adhesive 255 causes the optical filter 12c to move into the hollow portion 2
It is fixed in 42.

In the optical connector having the sixth light-shielding structure, the light of the reflection wavelength of the grating 126 is radiated from the grating 126 to the clad 124 and the clad 124.
Light emitted from the clad 124 across the light absorption portion 1
It is characterized by absorption by 36.

In the conventional optical connector, the ferrule is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, as can be seen from the experiments described with reference to FIGS. 8 to 11, when the tip portion including the grating 116 of the optical fiber 100, which is an optical filter, is housed in the ferrule, the grating 116
The light emitted from the clad 114 is reflected by the inner surface of the ferrule, returns to the clad 114 again, and travels in front of the grating 116. Therefore, the light is not necessarily blocked sufficiently by the optical filter.

The optical connector having the sixth light-shielding structure was devised in view of such a fact. That is, in the optical connector of FIG. 26, the light emitted from the grating 126 to the clad 124, reaching the outer surface of the clad 124 and exiting the clad 124 is absorbed by the light absorbing portion 136. Therefore, the phenomenon that the light emitted from the grating 126 to the clad 124 is reflected from the inner surface of the through hole 130 of the ferrule 13 and returns to the inside of the optical filter 12 after being emitted from the clad 124 is suppressed. It This reduces the power of unnecessary radiation light that is emitted to the cladding 124 and passes through the filter region 122 among the light of the reflection wavelength of the grating 126, so that the optical connector of FIG.
It has a higher light blocking rate than before.

In the sixth light shielding structure shown in FIG. 26, the light absorbing portion 13 is placed at a position surrounding the grating 126.
6 is provided, the position of the light absorbing portion 136 is not limited to this example. The light emitted from the grating 126 to the cladding 124 is
From each part of 6, proceed to a site located diagonally forward. Therefore, by providing the light absorbing portion 136 at a portion located diagonally forward from each portion of the grating 126, the light blocking rate can be sufficiently increased.

FIG. 28 is a side sectional view showing a modification of the above-mentioned optical connector (corresponding to the sectional view taken along the line AA in FIG. 5).
It is. The light absorbing portion 136 of the optical connector is provided in front of the optical connector of FIG. 26 (close to the end face 131). As described above, from the grating 126 to the cladding 1
Since the light radiated to 24 travels obliquely forward of the grating 126, the light emitted from the grating 126 is sufficiently absorbed if the light absorbing portion 136 is provided obliquely forward of the tip of the grating 126. It will be. Therefore, the optical connector of FIG. 28 also has a sufficiently high light blocking rate.

In the optical connector having the above-mentioned sixth light shielding structure (see FIGS. 26 and 28), the light absorbing portion 1
If the light absorbing material 36 has a refractive index that is substantially the same as the surface layer of the clad 124 of the optical filter 12c, the emitted light from the grating 126 is hardly reflected at the interface between the optical filter 12c and the light absorbing material. . As a result, the light emitted from the grating 126 is absorbed very efficiently by the light absorbing material, and a higher light blocking rate can be realized.

If the light absorbing material has a higher refractive index than the surface layer of the clad 124 of the optical filter 12, the light emitted from the grating 126 is totally reflected at the interface between the optical filter 12c and the light absorbing material. It becomes difficult to be played. Thereby, the light emitted from the grating 126 can be efficiently absorbed by the light absorbing material, and a higher light blocking rate can be realized.

Next explained is the seventh light-shielding structure of the optical connector of the second embodiment according to the invention.

FIG. 29 shows a seventh light-shielding structure (first application example).
FIG. 5 is a side sectional view showing the structure of an optical connector provided with
It is a cross-sectional view taken along the line A). 30 is the same as FIG.
Front view of the optical connector when viewed from the direction indicated by arrow E1 (corresponding to the front view when viewed from the direction indicated by arrow E in FIG. 5) Is.

As shown in FIG. 29, the optical connector having the seventh light shielding structure (first application example) is an optical fiber in which a grating 126 is formed on a single mode optical fiber having a core 123 and a clad 124. For accommodating the tip portion 121 of the optical filter 12 of the mold, inner diameter = 126 μm
The ferrule 13 (made of zirconia) having the through hole 130, the flange 24 attached to the holding portion 241 of the ferrule 13, and the first light shielding member 140 disposed in close contact with the end surface 131 of the ferrule 13. With.

The first light blocking member 140 is the optical filter 12
1.14 times the diameter D of the mode field of light propagating through
3. The core 123 has an opening whose center coincides with the center of the core 123. In general, the mode field diameter is about the same as the diameter of the core 102, and is much smaller than the diameter of the clad 124. The first light blocking member 140 may be a reflecting member or a light absorbing member. Aluminum, gold, tungsten, titanium, or the like can be preferably used as the material of the reflecting member. Further, as the material of the light absorbing material, resin or glass mixed with erbium, praseodymium, carbon or the like can be preferably adopted. Since erbium has an absorption peak at a wavelength near 1.55 μm and praseodymium has a absorption peak at a wavelength near 1.31 μm,
It is suitable for blocking light of each wavelength.

The ferrule 13 is a cylindrical member having a through hole 130 for accommodating the tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed. This through hole 13
The filter area in which the grating 126 is formed is housed in the zero area.

The flange 24 is a tubular holding member in which the rear end of the ferrule 13 is attached to the holding portion 241. In the hollow portion 242 of the flange 24, the coating 115
An optical filter 12 with a mark is stored. An adhesive 257 is filled between the coating 115 of the optical filter 12 and the hollow portion 242. The optical filter 12 is fixed in the hollow portion 242 of the flange 24 by the adhesive 257.

The first light-shielding member 140 may be a plate-like member that is attached to the end surface 131 of the ferrule 13 and arranged. In addition, after inserting the optical filter 12 into the ferrule 13, the end face 131 of the ferrule 13 and the optical filter 1 are inserted.
It may be formed on the second light emitting end face 125 by vapor deposition or the like.

The blocking of the emitted light, which is generated in the grating 126 and proceeds to the clad 124, is achieved by the optical connector having the seventh light shielding structure (first application example) as follows.

In the optical filter 12 in which the core 126 is formed with the grating 126 whose refractive index changes along the optical axis direction (longitudinal direction), the mode field diameter (MFD) changes with the change of the refractive index. Therefore, before the light enters the grating 126, a part of the light that has traveled while satisfying the confinement condition in the vicinity of the core 123 is emitted toward the cladding 124. Such emitted light is mainly reflected by the inner surface of the through hole 130 of the ferrule 13, and a part of the emitted light reaches the light exit opening.

In the optical connector of FIG. 29, the optical filter 12
The first light blocking member 140 limits the opening of the light emitting end face 125 of the above. Diameter D3 of the opening of the first light shielding member 140
Is much smaller than the diameter of the clad 124, so even if the optical filter 12 is close to the opening of the first light shielding member 140.
Most of the light traveling through the clad 124 is blocked and is not emitted from the opening of the first light blocking member 140.

On the other hand, the diameter of the opening of the first light shielding member 140 is 1.14 times the mode field diameter of the optical filter 12. Therefore, through the grating 126, the core 1
Since only about 0.1 dB of the intensity of light having a wavelength other than the reflection wavelength that travels only around 23 is blocked, most of it can be emitted.

The inventors described all of the above-mentioned phenomena in FIG.
It confirmed using the apparatus shown by.

Next explained is the seventh light-shielding structure (second application example) of the optical connector of the second embodiment according to the invention.

FIG. 31 shows a seventh light-shielding structure (second application example).
FIG. 5 is a side sectional view showing the structure of an optical connector provided with
It is a cross-sectional view taken along the line A). FIG. 32 corresponds to FIG.
5 is a front view of the optical connector when viewed from the direction indicated by arrow E2 (corresponding to the front view when the optical connector of FIG. 5 is viewed from the direction indicated by arrow E in FIG. 5). )
It is.

As shown in FIG. 31, the optical connector provided with the seventh light-shielding structure (second application example) is different from the optical connector of FIG.
Through-hole 1 for accommodating the filter region 122 in which 6 is formed
In the ferrule 13D having 30, the through hole 13
0, the diameter of the light exit opening is set to 1.degree. Of the mode field diameter of the waveguide type optical filter 20.
The difference is that a protrusion 141 for limiting the diameter D4 to 14 times is provided. The ferrule 13D is made of reflective zirconia, and the center of the opening defined by the protrusion 141 coincides with the center of the core 123.

Blocking of radiated light generated in the grating 126 and propagating to the cladding 124 by the optical connector of FIG. 31 is achieved as follows.

Like the optical connector of FIG. 29, the core 123
In the optical filter 12 in which the grating 126 whose refractive index changes along the optical axis direction (longitudinal direction) is formed, since the mode field diameter (MFD) changes with the change of the refractive index, the grating 126 Even light that has traveled while satisfying the confinement condition in the vicinity of the core 123 before being incident is partly emitted toward the cladding 124. Such synchrotron radiation is mainly due to the ferrule 13D
After being reflected by the inner surface of the through hole 130, part of the emitted light reaches the light exit opening.

In the optical connector of FIG. 31, the ferrule 13
The light emission opening is defined by the protrusion 141 provided at the opening portion of the D through hole 130. Diameter D4 of this light exit opening
Is much smaller than the diameter of the clad 124, so most of the light traveling through the clad 124 of the optical filter 12 near the light exit opening is reflected and the projection 1
No light is emitted from the light exit aperture defined by 41.

Further, similarly to the optical connector shown in FIG. 29, the diameter D4 of the light exit opening is 1.14 times the mode field diameter of the optical filter 12. Therefore, the grating 126
Since only about 0.1 dB of the intensity of light having a wavelength other than the reflection wavelength that travels only in the vicinity of the core 123 through the core is blocked, most of the light can be emitted.

Note that these facts have also been confirmed by the inventors using the experimental apparatus shown in FIG.

Further, it is necessary to process the end portion of the clad 124 in accordance with the shape of the tip portion of the ferrule 13D so that the light emitting end face of the optical filter 12 is substantially aligned with the light emitting opening of the ferrule 13. Is preferable from the viewpoint of the emission efficiency.

Next explained is the seventh light-shielding structure (third application example) of the optical connector of the second embodiment according to the invention.

FIG. 33 shows a seventh light-shielding structure (third application example).
FIG. 5 is a side sectional view showing the structure of an optical connector provided with
It is a cross-sectional view taken along the line A). FIG.
5 is a front view of the optical connector when viewed from the direction indicated by arrow E3 (corresponding to the front view of the optical connector viewed in the direction indicated by arrow E in FIG. 5). )
It is.

As shown in FIG. 33, the optical connector provided with the seventh light shielding structure (third application example) is shown in FIGS.
End face 131 of the ferrule 13 as compared with the optical connector No. 1
Through hole 130 near the opening of through hole 130 located at
The second light shielding member 142 that limits the diameter of the light emission opening to a diameter D5 that is 1.14 times the mode field diameter of the optical filter 12 is provided in the internal space of the above. The center of the opening defined by the second light shielding member 142 coincides with the center of the core 123.

In the optical connector of FIG. 33, the second light shielding member 142 can be arranged near the opening of the through hole 130 of the ferrule 13 before the optical filter 12 is inserted, and the ferrule 13 can be arranged. It is also possible to insert the optical filter 12 whose tip is processed into the through hole 130 and then bury it in the through hole 130.

The shielding of the emitted light, which is generated in the grating 126 and proceeds to the clad 124, by the optical connector having the seventh light shielding structure (third application example) is achieved as follows.

Like the optical connector of FIG. 29, the core 123
In the optical filter 12 in which the grating 126 whose refractive index changes along the optical axis direction (longitudinal direction) is formed, since the mode field diameter (MFD) changes with the change of the refractive index, the grating 126 Even light that has traveled while satisfying the confinement condition in the vicinity of the core 123 before being incident is partly emitted toward the cladding 124. Such emitted light is mainly reflected by the inner surface of the through hole 130 of the ferrule 13, and a part of the emitted light reaches the light emission opening defined by the second light shielding member 142.

In the optical connector of FIG. 33, the ferrule 13
A second light blocking member 142 defining a light exit opening is formed near the opening of the through hole 130, which is located on the end surface 131 of the. Since the diameter D5 of the light emission opening defined by the second light shielding member 142 is much smaller than the diameter of the clad 124, even light that travels through the clad 124 of the optical filter 12 near the light emission opening. However, most of them are reflected and are not emitted from the light emission aperture.

Further, similarly to the optical connector of FIG. 29, the second connector
The diameter of the light exit aperture defined by the light blocking member 142 is 1.14 times the mode field diameter of the optical filter 12.
Therefore, the intensity of light having a wavelength other than the reflection wavelength that propagates only near the core through the grating 126 is approximately 0.1 dB.
Is cut off, so most of it can be emitted.

The end portion of the clad 124 is pre-processed in accordance with the shape of the internal space formed by the through hole 130 of the ferrule 13 and the second light shielding member 142, and the light emitting end surface of the optical filter 12 is irradiated with light. From the viewpoint of the emission efficiency from the light emission opening, it is preferable to make it substantially coincide with the emission opening.

Next explained is the eighth light shielding structure of the optical connector of the second embodiment according to the invention.

FIG. 35 shows an eighth light shielding structure (first application example).
It is a top view which shows the optical connector (only a plug part) provided with. FIG. 36 is a sectional view of each part showing a part of the assembly process of the optical connector taken along the line F1-F1 of FIG. 35 (A- in FIG. 5).
It is a cross-sectional view taken along the line A). In addition, FIG.
35 is a cross-sectional view of the optical connector taken along the line H1-H1 of FIG. 35, and FIG. 38 is a cross-sectional view of the optical connector taken along the line G1-G1 of FIG.

The optical connector having the eighth light-shielding structure (first application example) is for connecting the optical filter 12 shown in FIG. 36 to other optical elements (optical fiber, semiconductor element, etc.). Yes, it accommodates the tip portion 121 of the optical filter 12. Specifically, this optical connector includes a ferrule 13E having a through hole 130 for accommodating the front end portion 121 of the optical filter 12, and a flange 24 having a rear end portion of the ferrule 13E attached to its holding portion 241. Has been done. In the predetermined part of the ferrule 13E,
A cutout portion 190 is provided.

As shown in FIG. 36, this optical filter 12 is an optical filter in which a grating 126 is formed in a single mode optical fiber having a core 123 and a clad 124. The grating 126 is located in the tip portion 121 of the optical filter 12 and has a filter region 12
It is formed in the core of 2.

The optical filter 12 is used as an OT.
The use in an inspection system of an optical communication network using a DR device can be mentioned. The tip portion 12 of this optical filter 12
1 is inserted into the through hole 130 of the ferrule 13E of the optical connector.

Next, each component of the optical connector having the eighth light shielding structure (first application example) will be described with reference to FIGS. The ferrule 13E has a tip portion 121 from which the resin coating 115 of the optical filter 12 is removed.
Is a member having a through hole 130 for housing the. As shown in FIGS. 36 and 38, the through hole 130 of the ferrule 13E extends along the central axis of the ferrule 13E. The above-mentioned tip portion 121 of the optical filter 12 is inserted into the through hole 130. Flange 24
Is a tubular holding member in which the rear end of the ferrule 13E is attached to the holding portion 241.
A portion of the optical filter 12 covered with the resin coating 115 is housed in the hollow portion 242.

The optical connector provided with the eighth light shielding structure (first application example) is the optical filter 1 of the ferrule 13E.
It is characterized in that a cutout portion 190 is provided in a portion located diagonally forward of the grating 126 when the two are accommodated. As a result, when the optical filter 12 is housed in the through hole 130 of the ferrule 13E, the grating 1 of the light of the reflection wavelength of the grating 126
The light emitted from 26 to the clad 124 and emitted from the optical filter 12 passes through the cutout portion 190 and is emitted to the outside of the ferrule 13E. As a result, the optical filter 12
The light blocking rate will increase.

In the conventional optical connector, the ferrule is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, as can be seen from the experiments described with reference to FIGS. 8 to 11, when the tip portion including the grating 116 of the optical fiber 100, which is an optical filter, is housed in the ferrule, the grating 116
The light emitted from the clad 114 is reflected by the inner surface of the ferrule, returns to the clad 114 again, and travels in front of the grating 116. Therefore, the light is not necessarily blocked sufficiently by the optical filter.

In view of such a fact, FIG. 35 and FIG.
The ferrule 13E of the optical connector shown in FIG. 6 is provided with a cutout portion 190 so as to be located in a region where the radiation light from the grating 126 is incident when the optical filter 12 is housed in the through hole 130. That is, FIG.
5 and the optical connector shown in FIG.
When 2 is housed in the through hole 130, the light having the reflection wavelength of the grating 126, which is emitted from the grating 126 to the clad 124, reaches the outer surface of the clad 124 and exits the clad 124, is cut out 190.
And is emitted to the outside of the ferrule 13E. Therefore, the light emitted from the grating 126 to the clad 124 is emitted from the clad 124, is then reflected by the inner surface of the through hole 130 of the ferrule 13E, returns to the inside of the optical filter 12, and travels in front of the grating 126. This phenomenon is suppressed. As a result, of the light of the reflection wavelength of the grating 126, the light is radiated to the clad 124 and the filter region 122
As a result, the power of light passing therethrough is reduced, and as a result, the optical connector shown in FIGS. 35 and 36 increases the light blocking rate of the optical filter 12.

As shown in FIG. 11, the light emitted from the grating 116 to the clad 114 travels from each part of the grating 116 to a portion located diagonally forward. Therefore, the cutout portion 19 is formed in the region of the ferrule 13E located diagonally forward of the filter region 122.
By providing 0, the light blocking rate of the optical filter 12 can be sufficiently increased.

Notch 19 provided in ferrule 13E
The length of 0 (here, the length along the optical axis direction (longitudinal direction) of the optical connector) may be designed as follows. As shown in FIG. 39, considering the case where light travels in an optical fiber having a relative refractive index difference Δ between the core and the clad at an angle of θ with respect to the axial direction of the optical fiber, Θ that satisfies the condition of total internal reflection
The maximum value θ _{MAX of} is represented by θ _MAX = sin ⁻¹ {(2Δ) ^1/2 }. Since the relative refractive index difference Δ between the core 123 and the clad 124 in the optical filter 12 is 0.0035, θ _MAX becomes about 4.8 ° in this case.

On the other hand, the distance (L in FIG. 39) that the light traveling in the core travels until it reaches the outer surface of the clad after being reflected by the outer surface of the clad is equal to the outer diameter of the clad. Then, it is represented by L = a / tan θ.

Considering the case of θ = θ _MAX = 4.8 °,
Since the outer diameter a of the optical filter 12 is 125 μm, L =
125 μm / tan (4.8 °) = about 1488 μm. This is because the light that satisfies the boundary condition of total reflection is clad 1
It is the distance traveled until it reaches the outer surface of the cladding 124 again after being reflected by the outer surface of 24. In the optical filter 12, the grating 126 to the clad 124
Since the light radiated to the surface travels at an angle larger than at least θ _MAX , this radiated light is emitted from the cladding 1.
The distance traveled after reaching the outer surface of the cladding 124 after being reflected by the outer surface of 24 is 1488 μm or less. Therefore, if the length of the cutout portion 190 is at least 1488 μm or more, the radiated light from the grating 126 reaches the outer surface of the clad 124 exposed by providing the cutout portion 190 at least once. , Ferrule 13E through cutout 190
Is emitted to the outside of. Therefore, from the viewpoint of increasing the light emission efficiency from the cutout portion 190, the length of the cutout portion 190 along the axial direction (longitudinal direction) of the optical connector is preferably 1488 μm or more.

It is more preferable that the notch 190 is filled with a refractive index matching material 700 having a refractive index substantially matching that of the clad 124 (see FIG. 40). In this way, when the optical filter 12 is housed in the through hole 130 of the ferrule 13E, the emitted light from the grating 126 is hardly reflected on the outer surface of the clad 124, and almost all of it is inside the refractive index matching material 700. It will be incident. Therefore, the light emitted from the grating 126 is emitted from the cutout portion 190 very efficiently, and the light blocking rate of the optical filter 12 can be greatly increased. It is sufficient that the refractive index of the refractive index matching material 700 matches the refractive index of the clad 124 so that the light reflectance on the outer surface of the clad 124 is 10% or less.

FIG. 40 is a plan view of an optical connector having an eighth light shielding structure (first application example) obtained through the assembling process of FIG. 41 is a cross-sectional view of the optical filter taken along the line H2-H2 of FIG. The tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed is inserted into the through hole 130 of the ferrule 13E, and the grating 1
26 is also accommodated in the through hole 130 of the ferrule 13E. The optical filter 1 is provided in the hollow portion 242 of the flange 24.
The portion with the second resin coating 115 is accommodated. An adhesive is filled between the coating 115 of the optical filter 12 and the hollow portion 242 of the flange 24, and the optical filter 12 is fixed in the hollow portion 242 by this adhesive. The internal structure of the flange 24 is the same as that of the optical connector described above (for example, FIG. 18).

In the optical connector having the eighth light shielding structure (first application example), the light emitted from the grating 126 to the clad 124 to reach the outer surface of the clad 124 and emitted from the clad 124 is cut out 190. And is radiated to the outside of the ferrule 13E. This allows
Clad 1 of the light of the reflection wavelength of the grating 126
The power of the light emitted at 24 and passing through the filter area is reduced. Therefore, the optical connector of FIG. 40 has a high light blocking rate, and can be suitably used as a component of an optical line inspection system.

Next, an eighth light shielding structure (second application example) of the optical filter according to the second embodiment of the present invention will be described.

FIG. 42 shows an eighth light shielding structure (second application example).
It is a top view which shows the optical connector (only a plug part) provided with. 43 is a sectional view of each part showing a part of the assembly process of the optical connector taken along the line F2-F2 of FIG. 42 (A- in FIG. 5).
It is a cross-sectional view taken along the line A). In addition, FIG.
42 is a sectional view of the ferrule 13F taken along the line H3-H3 of FIG. 42, and FIG. 45 is a sectional view of the ferrule 13F taken along the line G2-G2 of FIG.

The optical connector of FIG. 43 has a ferrule 13F having a through hole 130 in which the tip portion 121 of the optical filter 12 is housed, as in the case of the optical connector of FIG.
The rear end portion of the ferrule 13F is composed of the flange 24 attached to the holding portion 241.

In the optical connector of FIG. 43, the ferrule 13
An elliptical through hole 191 is provided in a region located in front of the grating 126 when the F optical filter 20 is housed in the through hole 130. This through hole 191
Penetrates the ferrule 13F so as to be orthogonal to the through hole 130 of the ferrule 13F.

The optical connector of FIG. 43 has a structure in which when the optical filter 12 is housed in the through hole 130, the grating 12
The light having the reflection wavelength of 6 that is emitted from the grating 126 to the clad 124, reaches the outer surface of the clad 124, and exits the clad 124 passes through the through hole 191 and is emitted to the outside of the ferrule 13F. ing. Therefore, from the grating 126 to the cladding 12
A phenomenon in which the light radiated to the laser beam 4 is emitted from the clad 124, reflected on the inner surface of the through hole 130 of the ferrule 13F, returns to the optical filter 12 again, and travels in front of the grating 126 is suppressed. It As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced, so that the optical connector including the eighth light shielding structure (second application example) is The light blocking rate of the optical filter 12 will be increased.

As shown in FIG. 11, the light emitted from the grating 116 to the clad 114 travels from each part of the grating 116 to a portion located diagonally forward. Therefore, like the present invention, if the through hole 191 is provided in the region of the ferrule 13F that is located diagonally forward of each part of the grating 126, the light blocking rate of the optical filter 12 can be sufficiently increased.

The eighth light-shielding structure (second application example)
Then, the hole 191 penetrating the ferrule 13F is provided. However, if the hole is such that the surface of the optical filter 12 is exposed when the optical filter 12 is housed in the through hole 130, it is necessary to penetrate the ferrule 13F. Not necessarily. Even in this case, the light blocking rate of the optical filter 12 can be sufficiently increased.

FIG. 46 is a plan view showing an optical connector obtained through the assembling process shown in FIG. FIG.
FIG. 47 is a cross-sectional view of the ferrule 13F taken along the line H4-H4 of FIG. 46. The tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed is the through hole 13 of the ferrule 13F.
0, and the grating 126 is also housed in the through hole 130 of the ferrule 13F. The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 with the resin coating 115. An adhesive is filled between the coating 115 of the optical filter 12 and the hollow portion 242 of the flange 24. The optical filter 12 is fixed in the hollow portion 242 by this adhesive.

In the optical connector of FIG. 46, the light is emitted from the grating 126 to the clad 124 so that the clad 1 is emitted.
The light that reaches the outer surface of 24 and exits from the clad 124 passes through the through hole 191 and is emitted to the outside of the ferrule 13F. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced. Therefore, the optical connector of FIG. 46 has a high light blocking rate and can be suitably used as a component of an inspection system of an optical line.

Next, the ninth light shielding structure of the optical connector according to the second embodiment of the present invention will be described.

FIG. 48 is a sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) showing the structure of the optical connector having the ninth light shielding structure. Further, FIG. 49 shows an arrow E4 of FIG.
4 when the optical connector is viewed from the direction shown in FIG.
8 is a front view of the optical connector of No. 8 (corresponding to the front view of the optical connector seen from the direction shown by arrow E in FIG. 5). This optical connector accommodates an optical fiber type optical filter 12 in which a grating 126 is formed in a single mode optical fiber having a core 123 and a clad 124, and an end portion 121 of the optical filter 12, and an inner diameter = 126.
Ferrule 13 having a through hole 130 of μm, and flange 2 that holds this ferrule 13 with its holding portion 241.
4. The ferrule 13 is made of zirconia. The optical filter 12 is used as an OTD.
One example is use in an inspection system of an optical communication network using an R device.

As shown in FIG. 48, the optical filter 12
Of these, the grating 126 is formed at a position apart from the end surface 125 of the optical filter 12 by D6 (> 3 mm).

A reference numeral 115 in FIG. 48 is a UV cut resin coating covering the surface of the clad 124, and has a role of protecting the core 123 and the clad 124. The resin coating 115 is removed from the tip portion 121 of the optical fiber 12 because the core 123 is irradiated with ultraviolet light when the grating 126 is manufactured as described above.

The ferrule 13 is a member having a through hole 130 for accommodating the tip portion 121 from which the resin coating 115 of the optical filter 12 has been removed. The filter region 1 in which the grating 126 is formed at the tip portion 121
22 are included.

The flange 24 is a tubular holding member in which the rear end of the ferrule 13 is attached to the holding portion 241. In the hollow portion 242 of the flange 24, the coating 115
An optical filter 12 with a mark is stored. An adhesive 257 is filled between the coating 115 of the optical filter 12 and the hollow portion 242 of the flange 24. This adhesive 2
The optical filter 12 is fixed in the hollow portion 242 by 57.

Here, in the optical filter in which the core has a grating whose refractive index changes along the optical axis direction (longitudinal direction), the mode field diameter (MFD) changes with the change of the refractive index. . For this reason, even if the light travels while satisfying the confinement condition in the core before being incident on the grating, a part of the light is emitted toward the cladding. Then, these emitted lights are directly emitted from the emission end face if the generation location is near the emission end face. On the other hand, if it is far from the place of generation, most of the emitted light reaches the outer circumference of the clad and is reflected once or more at the outer peripheral interface or is reflected once or more at the incident surface to the storage member via the outer peripheral interface of the clad. Light is emitted from the emission end face. In general, the storage member is made of a material having relatively high light reflectivity, such as metal, from the viewpoint of mechanical strength, and therefore exhibits a higher reflectance than the interface reflection at the outer peripheral portion of the clad. Therefore, a preferable storage member (for example, ferrule) for storage
When the optical filter has a hollow portion having a diameter substantially the same as the outer diameter of the optical filter, reflection on the incident surface to the housing member becomes a particular problem.

The optical connector shown in FIG. 48 is equivalent to the grating 1
The light emitted from the clad 124 after being emitted from the grating 126 to the clad 124 among the lights having the reflection wavelengths of 26 is always generated at a position 3 mm or more away from the light emitting end face 125 of the optical filter 12. It is characterized by that.

The optical connector shown in FIG. 48 has been realized in view of such a fact. That is, in the optical connector having the ninth light shielding structure, the emitted light emitted from the grating 126 to the clad 124 is reflected on the outer surface of the clad or the inner surface of the ferrule many times before reaching the light emitting surface.

Therefore, the intensity of the radiated light reaching the emission end face is greatly attenuated as compared with the intensity of the radiated light at the time of generation.
As a result, in the light emitted from the emission end face of the waveguide type optical filter 20, the component of the light having the reflection wavelength at the diffraction grating 16 is effectively blocked.

The inventors have already confirmed the above phenomenon using the experimental apparatus shown in FIG.

Next, an experiment will be described in order to verify the effectiveness of the optical connector (ninth light shielding structure) of the present invention. 50 to 53 are explanatory views of this experiment.

First, as shown in FIG. 50, like the optical filter 12, an optical waveguide comprising a core 501 and a clad 502 is prepared. Excimer laser (oscillation wavelength = 2
48 nm), the grating pitch is changed from the tip of the optical waveguide to 1 nm / 1 mm, and the grating pitch is 1550 nm.
Form 503 continuously changing from 1 to 1542 nm,
A waveguide type optical filter 500 was produced. Then, the wavelength dependency of the transmittance of the optical filter 500 was measured without being mounted on the plug (ferrule 504). As a result, the measurement results shown in the graph of FIG. 51 were obtained. In the figure, 310 and 300 are a file adapter and a spectrum analyzer, respectively, as mentioned in the description of the experimental apparatus in FIG.

Next, as shown in FIG. 52, the optical filter 500 is inserted into a ferrule 504 made of zirconia having a through hole with an inner diameter of 126 μm and fixed with an adhesive (353ND manufactured by Epoxy Technology Co., Ltd.). It was plugged in. The wavelength dependence of the transmittance of this optical filter was measured. As a result, the measurement results shown in the graph of FIG. 53 were obtained.

As a result of comparison between FIG. 51 and FIG. 53, light having a wavelength corresponding to 3 mm from the light emitting end face position of the optical filter 500 is generated by the plug (ferrule 504) as compared with the case where the plug is not mounted (FIG. 50). In the case of mounting (FIG. 52), the transmittance is remarkably reduced, but the light of the wavelength corresponding to 3 mm or more from the light emitting end face is not mounted in the connector (FIG. 5).
It was confirmed that the amount of reduction in the transmittance was smaller in the case of mounting the connector (FIG. 52) than in 0).

The present invention is not limited to the above embodiment, but can be modified. For example, ferrule 1
Even if the material of 3 is a material having reflectivity other than zirconium, the same effect as that of the present invention can be obtained.

Next explained is the tenth light shielding structure for an optical connector according to the second embodiment of the invention.

FIG. 54 is a side sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) of each part showing a part of the assembling process of the optical connector having the tenth light shielding structure. 55 is a cross-sectional view (corresponding to the cross-sectional view taken along the line CC of FIG. 5) of the optical connector in the portion indicated by the arrow C6 in FIG. 54. This optical connector is for connecting the optical filter 12 and another optical element, and can accommodate the optical filter 12. Specifically, the optical connector shown in FIG. 54 has a through hole 130 accommodated in the tip portion 121 of the optical filter 12.
13G having a ferrule 13G, and a flange 2 having a rear end portion of the ferrule 13G attached to the holding portion 241.
And 4.

The optical filter 12 is an optical fiber type optical filter in which a grating 126 is formed in a single mode optical fiber having a core 123 and a clad 124. The grating 126 is formed on the tip portion 121 of the optical filter 12.

The reference numeral 115 in FIG. 54 is a UV cut resin coating for covering the surface of the clad 124, and has a role of protecting the core 123 and the clad 124. As shown in FIG. 54, the optical fiber 12
The resin coating 115 has been removed from the tip portion 121 of the optical connector, and this tip portion 121 is the ferrule 13 of the optical connector.
It will be inserted into the G through hole 130.

The ferrule 13G has a tip portion 121 (outer diameter 125 with the resin coating 115 of the optical filter 12 removed.
This is a member having a through hole 130 for housing (μm). The through hole 130 extends along the central axis of the ferrule 13G, and the above-mentioned tip portion 121 of the optical filter 12 is inserted into the through hole 130. The flange 24 has a holding portion 241 at the rear end of the ferrule 13G.
Is a tubular holding member attached to. A portion of the optical filter 12 covered with the resin coating 115 is housed in the hollow portion 242 of the flange.

In the optical connector having the tenth light shielding structure, the through hole 130 of the ferrule 13G has the standard portion 133.
It is composed of a and an enlarged portion 134a. Standard part 13
3a has a cross section perpendicular to the central axis of the through hole 130 having a diameter of 1
It is a circle of 26 μm, and the coating 11 of the optical filter 12
5 has a cross section that is substantially the same as the cross section of this tip portion 121 so that the removed tip portion 121 can be held.
Further, the standard portion 133a has a tip surface 131 (optical filter 1) of the ferrule 13G at the tip portion of the ferrule 13G.
2 is provided in a portion including a surface to which the end surface 125 of the optical filter 12 is exposed. On the other hand, the enlarged portion 134a is a circle whose cross section orthogonal to the central axis of the through hole 130 has a diameter larger than that of the standard portion 133a. Specifically, the enlarged portion 134a has a cross-sectional diameter of 500 μm and extends from the rear end of the ferrule 13G toward the standard portion 133a, and the cross-sectional diameter of 500 μm to 1 μm.
It continuously changes along the axial direction up to 26 μm and is finally connected to the standard portion 133a.
The enlarged portion 134a is provided in the through hole 130 with the optical filter 12a.
Grating 12 when the tip portion 121 of the
6 is provided in a region surrounding the periphery of the filter region 122 in which the 6 is formed.

When the optical filter 12 is housed in the ferrule 13G of FIG. 54, a gap 135a is formed between the inner surface of the through hole 130 of the ferrule 13G and the outer surface of the optical filter 12 in the enlarged portion 134a. As a result, of the light of the reflection wavelength of the grating 126, the light emitted from the grating 126 to the clad 124 is
5a, and as a result, the optical filter 12
The light blocking rate will increase.

The inventors have already used the experimental apparatus shown in FIGS. 8 to 11 to determine that the light emitted from the grating 126 formed in the core 123 of the optical filter 12 toward the cladding 124 is the light of the optical filter 12. It has been confirmed that the cutoff rate is reduced.

Conventionally, the ferrule of the optical connector is made of a material having high light reflectivity such as zirconia, and its inner surface is a mirror surface. Therefore, the grating 11 of the optical fiber 100, which is an optical filter,
When the tip including 6 is housed in the ferrule, the light emitted from the grating 116 and emitted from the clad 114 is reflected by the inner surface of the ferrule and is again clad 114.
Since it returns to the inside and travels in front of the grating 116, the light is not always sufficiently blocked by the optical filter (see FIGS. 8 to 11).

The optical connector having the tenth light shielding structure is
It was devised in view of such a fact. As described above, the ferrule 13G shown in FIG.
When the ferrule 1
A gap 135a is formed between the 3G and the optical filter 12. This gap 135a is the ferrule 13G
When the optical filter 12 is housed in the through hole 130 of the ferrule 13G, the light emitted from the grating 126 to the clad 124 out of the light of the reflection wavelength of the grating 126 is not provided. , And spreads to the gap 135a outside the clad 124. After that, the emitted light from the grating 126 reaches the standard portion 133a, but the leaked light component distributed in the gap 135a in the emitted light from the grating 126 has a cross-sectional diameter of the through hole 130 in the axial direction. It is blocked by the inner surface of the through-hole 130 of the ferrule 13G at the portion that continuously changes along. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced, so that the optical connector of FIG. 54 can increase the light blocking rate of the optical filter 12. .

According to the knowledge of the present inventors, the enlarged portion 134
If the diameter of the cross section of a is larger than the outer diameter of the portion of the optical filter 12 where the resin coating 115 is removed by 50 μm or more, the radiated light from the grating 126 is sufficiently spread, and the ratio of being blocked by the ferrule 13G is high. Since it becomes higher, the light blocking rate of the optical filter 12 can be sufficiently increased. The above condition corresponds to the cross-sectional area of the enlarged portion 134a being twice or more the cross-sectional area of the optical filter 12.

Also, the through hole 13 of the ferrule 13G.
When the optical filter 12 is housed in the space 0, the above-mentioned gap 13
It may be considered that 5a is filled with an adhesive. At this time,
If the diameter of the cross section of the enlarged portion 134a is 700 μm or more larger than the outer diameter of the portion of the optical filter 12 where the resin coating 115 is removed, the stress exerted on the grating 126 during the curing of the adhesive increases. Since there is a possibility that the characteristics of the grating 126 may be greatly changed, it is not preferable.

In addition, the optical filter 1 is provided in the gap 135a.
2 is filled with a refractive index matching material having a refractive index substantially matching the surface layer of the clad 124, the ferrule 13
When the optical filter 12 is housed in the G through hole 130,
Light emitted from the grating 126 is hardly reflected on the outer surface of the optical filter 12. For this reason, the light emitted from the grating 126 spreads very efficiently to the gap 135a, and the light blocking rate of the optical filter 12 can be extremely increased.

When the gap 135a is filled with a refractive index matching material having a higher refractive index than the surface layer portion of the clad 124 of the optical filter 12, when the optical filter 12 is housed in the through hole 130 of the ferrule 13G. The emitted light from the grating 126 is less likely to be totally reflected on the outer surface of the optical filter 12. Therefore, the grating 126
The emitted light from the light efficiently spreads in the gap 135a, and the light blocking rate of the optical filter 12 can be greatly increased.

FIG. 56 is a sectional view showing the structure of the optical connector obtained through the assembling process shown in FIG. 54 (A- in FIG. 5).
It is a cross-sectional view taken along the line A). FIG. 57 corresponds to FIG.
FIG. 5 is a sectional view of the portion of the optical connector indicated by the arrow C7 in FIG.
(Corresponding to a sectional view taken along line C-C of FIG. The tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed is inserted into the through hole 130 of the ferrule 13G, and the grating 126 is arranged inside the enlarged portion 134a. The standard portion 133 a of the through hole 130 is provided in the optical filter 12
The region including the end face 125 of the optical filter 12 is surrounded so as to be almost in close contact with it, thereby holding the optical filter 12. Further, in the enlarged portion 134a, a gap 135a is formed between the outer surface of the optical filter 12 and the inner surface of the through hole 130 of the ferrule 13G. Hollow part 2 of flange 24
A portion of the optical filter 12 with the resin coating 115 is housed in the housing 42. Coating 11 of this optical filter 12
An adhesive 600 is filled between the hollow space 5 and the hollow portion 242. The optical filter 12 is fixed in the hollow portion 242 by the adhesive 600.

In the optical connector of FIG. 56, of the light of the reflection wavelength of the grating 126, the light emitted from the grating 126 to the clad 124 propagates while spreading to the gap 135a outside the clad 124. Thereafter, the emitted light from the grating 126 is emitted from the standard unit 133.
The leaked light component that reaches the a but is distributed in the gap 135a of the emitted light from the grating 126 is blocked by the inner surface of the through hole 130 of the ferrule 13G,
You cannot proceed any further. This allows
Clad 1 of the light of the reflection wavelength of the grating 126
The power of the light emitted by 24 and passing through the filter region 122 is reduced. Therefore, the optical connector having the tenth light shielding structure has a high light blocking rate and can be suitably used as a constituent element of an inspection system of an optical line.

Next, the eleventh light shielding structure of the optical connector according to the second embodiment of the present invention will be described.

FIG. 58 is a sectional view of each part showing a part of the assembling process of the optical connector having the eleventh light shielding structure (first application example) (corresponding to the sectional view taken along the line AA of FIG. 5). Is.
59 is a cross-sectional view (corresponding to the cross-sectional view taken along the line C-C of FIG. 5) of the optical connector in the portion indicated by the arrow C8 in FIG. 58. As shown in FIG. 59, in the ferrule 13H of the optical connector including the eleventh light shielding structure (first application example), the cross-sectional shape of the enlarged portion 134b of the through hole 130 is as shown in FIG.
Is different from the optical connector. That is, the expansion unit 134
In b, four grooves 135b are formed on the inner surface of the through hole 130 extending along the central axis of the ferrule 13H. Through hole 1 shown in FIGS. 58 and 59.
30 is a standard unit 1 so that the optical filter 12 can be held.
It has the same cross section as 33b, that is, a circular cross section with a diameter of 126 μm. Further, the four grooves 135 b extend along the central axis of the through hole 130, and each of the grooves 135 b.
b are arranged at equal intervals along the circumferential direction of the inner surface of the through hole 130 of the ferrule 13H.

In the ferrule 13H of FIG. 58, when the optical filter 12 is housed, the enlarged portion 134b of the through hole 130 is formed.
There is a gap between the groove 135b defined by and the outer surface of the optical filter 12. Therefore, similarly to the optical connector of FIG. 56, of the light of the reflection wavelength of the grating 126, the light emitted from the grating 126 to the clad 124 propagates to the groove 135b while propagating to the groove 135b.
The leakage light component distributed inside the through hole 1 of the ferrule 13H at the boundary between the enlarged portion 134b and the standard portion 133b.
It will be blocked by the inner surface of 30. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced, so that the optical connector including the eleventh light shielding structure (first application example) is also included. 54, the light blocking rate of the optical filter 12 can be increased.

Further, in the optical connector of FIG. 58, the through hole 13 of the enlarged portion 134b shown in FIGS.
0 has substantially the same cross section as the optical filter 12,
The optical filter 12 is properly held not only by the standard portion 133b but also by the enlarged portion 134b. Therefore, according to the optical connector of FIG. 58, the optical filter 12 can be held more reliably.

The optical filter 12 is placed in the groove 135b.
When the optical filter 12 is housed in the ferrule 13H when the index matching material 800 having a refractive index substantially matching the surface layer portion of the clad 124 is filled, the light emitted from the grating 126 is emitted from the outer surface of the optical filter 12. As a result, the light blocking rate of the optical filter 12 can be extremely increased.

If the groove 135b is filled with a refractive index matching material 800 having a refractive index higher than that of the surface layer portion of the clad 124 of the optical filter 12, when the optical filter 12 is housed in the ferrule 13H, the grating 126 will not be exposed. The radiated light is less likely to be totally reflected on the outer surface of the optical filter 12, so that the light blocking rate of the optical filter 12 can be greatly increased.

Next, FIG. 60 is a sectional view showing the structure of the optical connector obtained through the assembling process of FIG. 58 (AA in FIG. 5).
It corresponds to the cross-sectional view along the line). 61 is a cross-sectional view (corresponding to the cross-sectional view taken along the line CC of FIG. 5) of the optical connector in the portion indicated by the arrow C9 in FIG. 60. Optical filter 1
The removed tip portion 121 of the second resin coating 115 is inserted into the through hole 130 of the ferrule 13H, and the grating 126 is arranged in the enlarged portion 134b.
The standard portion 133b of the through hole 130 surrounds the tip portion 121 of the optical filter 12 so as to be almost in close contact with the standard portion 133b, thereby holding the optical filter 12. Further, in the enlarged portion 134b, the groove 135b formed in the outer surface of the optical filter 12 and the through hole 130 of the ferrule 13H.
There is a gap between The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 with the resin coating 115. An adhesive 600 is filled between the coating 115 of the optical filter 12 and the hollow portion 242.
With this adhesive 600, the optical filter 12 has a hollow portion 242.
Is fixed inside.

In the optical connector of FIG. 60, of the light of the reflection wavelength of the grating 126, the light emitted from the grating 126 to the clad 124 propagates while spreading to the groove 135b. Thereafter, the emitted light from the grating 126 reaches the standard portion 133b, but the leaked light component distributed in the groove 135b of the emitted light from the grating 126 is blocked by the inner surface of the through hole 130 of the ferrule 13H. It is impossible to move forward any further. As a result, the power of the light of the reflection wavelength of the grating 126 that is emitted to the cladding 124 and passes through the filter region 122 is reduced. Therefore,
The optical connector having the eleventh light shielding structure (first application example) has a high light blocking rate and can be suitably used as a constituent element of an optical line inspection system.

As shown in FIG. 60, the through hole 1
30 is the standard part 133 at the tip of the ferrule 13H
Although the optical connector has b, but does not have such a standard portion 133b and the groove 135b extends from the rear end of the ferrule 13H to the tip (including the end face 131), a certain effect is obtained. . That is, when the optical filter 12 is housed in such an optical connector, the grating 126
The light emitted from the grating 126 to the clad 124 among the light having the reflected wavelength advances to the groove 135b while spreading and is emitted from the tip of the ferrule 13H. Therefore, when the optical filter 12 is connected to an optical component having a light receiving surface having a cross-sectional area similar to that of the optical filter 12, the emitted light from the grating 126 is distributed inside the groove 135b. The leaking light component present does not enter this light portion, which increases the light blocking rate of the optical filter 12.

Next explained is the eleventh light-shielding structure (second application example) of the optical connector of the second embodiment according to the invention.

FIG. 62 is a side sectional view of each part (a sectional view taken along the line AA of FIG. 5) showing a part of the assembling process of the optical connector having the eleventh light shielding structure (second application example). Correspondence). 63 is a cross-sectional view (corresponding to the cross-sectional view taken along the line CC of FIG. 5) of the optical connector in the portion indicated by the arrow C10 in FIG. 62. The through hole 130 of the ferrule 13I is composed of a plurality of standard portions 133c having a cross section substantially the same as the cross section of the optical filter 12, and a plurality of enlarged portions 134b having a circular cross section with a diameter larger than the cross section of the optical filter 12. There is. The standard portion 133c and the enlarged portion 134c have the through hole 13
They are arranged alternately along the central axis of 0. Enlarging part 13
4c is located at a portion where the groove 135c is provided on the inner surface of the through hole 130 having a cross section substantially the same as the cross section of the optical filter 12. Through hole 13 shown in FIGS. 62 and 63.
0 is the standard unit 13 so that the optical filter 12 can be held.
It has the same cross section as 3c, that is, a circular cross section with a diameter of 126 μm. Each groove 135c extends along the circumference of the cross section of the through hole 130 while maintaining a constant depth. Further, the grooves 135c are arranged at equal intervals along the central axis of the through hole 130.

In the ferrule 13I of FIG. 62, when the optical filter 12 is housed, the enlarged portion 134c of the through hole 130 is formed.
There is a gap between the groove 135c defined by and the outer surface of the optical filter 12. Therefore, as in the case of the optical connector of FIG. 56, of the light of the reflected wavelength of the grating 126, the light emitted from the grating 126 to the cladding 124 enters the groove 135c. The leaked light component of the radiated light from the grating 126 that has entered the groove 135c is inside the groove 135c.
Since it is reflected by the inner surface (enlarged portion 134c) of the through hole 130 of I, it becomes difficult to travel forward and the strength is gradually attenuated. As a result, the grating 126
The power of the light of the reflected wavelength that is emitted to the clad 124 and passes through the filter region 122 is reduced.
Particularly, in this optical connector, the plurality of enlarged portions 134c and the plurality of standard portions 133c are alternately arranged, and the emitted light is reduced in each of the enlarged portions 134c, so that the effect of reducing the emitted light is accumulated, Finally, the emitted light from the grating 126 is greatly reduced. Therefore, the eleventh
The optical connector including the light shielding structure (second application example) can significantly increase the light blocking rate of the optical filter 12.

The optical filter 12 is inserted into the groove 135c.
When the optical filter 12 is housed in the ferrule 13I when the refractive index matching material 800 having a refractive index substantially matching the surface layer portion of the clad 124 is filled, the light emitted from the grating 126 is emitted from the outside of the optical filter 12. Since the light is hardly reflected on the surface, the light blocking rate of the optical filter 12 can be extremely increased.

If the groove 135c is filled with a refractive index matching material 800 having a refractive index higher than that of the surface layer of the clad 124 of the optical filter 12, when the optical filter 12 is housed in the ferrule 13I, the grating 126 is filled.
Since it becomes difficult for the emitted light from the total reflection to occur on the outer surface of the optical filter 12, the light blocking rate of the optical filter 12 can be greatly increased.

FIG. 64 is a sectional view (corresponding to the sectional view taken along the line AA of FIG. 5) showing the structure of the optical connector obtained through the assembling process of FIG. 65 is an arrow C of FIG.
Sectional drawing of the optical connector of the part shown by 11 (C- of FIG. 5)
It is a cross-sectional view taken along line C). The tip portion 121 of the optical filter 12 from which the resin coating 115 is removed is inserted into the through hole 130 of the ferrule 13I, and the enlarged portion 134c is located around the grating 126. The standard portion 133c of the through hole 130 surrounds the tip portion 121 of the optical filter 12 so as to be almost in close contact with the standard portion 133c, thereby holding the optical filter 12. Further, in the enlarged portion 134c, a gap is formed by the groove 135c provided on the outer surface of the optical filter 12 and the inner surface of the through hole 130 of the ferrule 13I. In the hollow portion of the flange 24, the portion of the optical filter 12 with the resin coating 115 is housed. An adhesive 600 is filled between the coating 115 of the optical filter 12 and the hollow portion 242. With this adhesive 600, the optical filter 12 has a hollow portion 242.
Is fixed inside.

In this optical connector, the grating 12
Of the light of the six reflected wavelengths, the light emitted from the grating 126 to the cladding 124 enters the groove 135c. This makes it difficult for the emitted light from the grating 126 to travel forward and gradually attenuates while being reflected in the groove 135c, so that the filter region 1 of the light of the reflected wavelength from the grating 126 is reduced.
The power of the light passing through 22 is reduced. Therefore, FIG.
The optical connector of No. 4 has a high light blocking rate and can be suitably used as a component of an inspection system of an optical line.

In the eleventh light shielding structure (second application example), the plurality of enlarged portions 134c are arranged so as to surround the entire grating 126.
The arrangement of is not limited to this. As shown in FIG. 11, from the grating 126 to the cladding 124.
The light radiated to the light travels obliquely forward from each part of the grating 126. Therefore, if the enlarged portion 134c is provided in the region diagonally forward of each portion of the grating 126, the light blocking rate will be sufficiently increased.

FIG. 66 is a side sectional view showing a modification of the optical connector of FIG. 64 (corresponding to the sectional view taken along the line AA of FIG. 5).
It is. In this optical connector, the enlarged portion 134c is shown in FIG.
Is provided in front of the optical connector as a whole. As described above, the light emitted from the grating 126 to the cladding 124 travels obliquely forward of the grating 126. Therefore, if the enlarged portion 134c is provided obliquely forward of the tip of the grating 126, the light emitted from the grating 126 will be emitted. The light will be sufficiently reduced. Therefore, the optical connector shown in FIG. 66 also has a sufficiently high light blocking rate, and can be suitably used as a component of an optical line inspection system. The ferrule 13I shown in FIG. 64 and the like can also be obtained by laminating disks having openings with different diameters.

Next explained is the eleventh light-shielding structure (third application example) of the optical connector according to the second embodiment of the invention.

FIG. 67 is a side face view (corresponding to a sectional view taken along the line AA in FIG. 5) showing the structure of an optical connector (only a plug portion) provided with an eleventh light shielding structure (third application example). ). In this ferrule 13J, the shape of the groove 135d defined by the enlarged portion 134d of the through hole 130 is shown in FIG.
Is different from the optical connector. 68 shows the ferrule 1
It is a figure which shows the expansion part 134d and the standard part 133d in 3J. The enlarged portion 134d defines a groove 135d formed on the inner surface of the through hole 130 having a cross section that is substantially the same as the cross section of the optical filter 12. This groove 135d has a through hole 130.
It differs from the optical connector of FIG. 64 in that it extends spirally around the center axis of the optical connector. The enlarged portion of the through hole referred to in this specification means a portion in which the cross-sectional area orthogonal to the axis of the through hole is larger than the cross-sectional area of the optical filter. In FIG. 67, the groove 135d is provided. Through hole 13
All of the portions where the cross-sectional area orthogonal to the central axis of 0 is larger than the standard portion 133d correspond to the enlarged portion 134d.

In the ferrule 13J of FIG. 67, when the optical filter 12 is housed, a gap is formed between the outer surface of the optical filter 12 and the groove 135d provided on the inner surface of the through hole 130 in the enlarged portion 134d. Therefore, of the light of the reflection wavelength of the grating 126, the grating 12
The light emitted from 6 to the clad 124 enters the groove 135d. As a result, the grating 12
The radiated light from No. 6 is less likely to travel forward and is gradually attenuated while being reflected in the groove 135d. Therefore, the power of the light having the reflection wavelength of the grating 126 that passes through the filter region 122 is reduced. Will be reduced. Therefore, the optical connector of FIG. 67 can also increase the light blocking rate of the optical filter 12, similarly to the optical connector of FIG.

Further, in the optical connector of FIG. 67, the inner surface of the through hole 130 of the ferrule 13J is continuously scraped, and one continuous spiral groove 135d is formed on the inner surface to form the enlarged portion 134d. It can be manufactured, and it is not necessary to provide a plurality of grooves 135d as in the optical connector of FIG. 64, so that the manufacturing is relatively easy.

The optical filter 12 is inserted into the groove 135d.
When the optical filter 12 is housed in the ferrule 13J, the radiated light from the grating 126 is filled with the refractive index matching material 800 having a refractive index substantially matching the surface layer portion of the clad 124 of the optical filter 12. The light blocking rate of the optical filter 12 can be greatly increased because the light is hardly reflected by the optical filter (FIGS. 69 and 70).
reference).

If the groove 135d is filled with a refractive index matching material 800 having a refractive index higher than that of the surface layer portion of the clad 124 of the optical filter 12, when the optical filter 12 is housed in the ferrule 13J, the optical fiber 12 will be separated from the grating 126. The radiated light is less likely to be totally reflected on the outer surface of the optical filter 12, so that the light blocking rate of the optical filter 12 can be greatly increased.

Next, FIG. 69 shows an eleventh light shielding structure (third
FIG. 5 is a cross-sectional view showing the structure of an optical connector including an application example (FIG. 5).
(Corresponding to a sectional view taken along line AA of FIG. The tip portion 121 of the optical filter 12 from which the resin coating 115 has been removed is inserted into the through hole 130 of the ferrule 13J, and the grating 126 is arranged inside the enlarged portion 134d. The standard portion 133d of the through hole 130 is provided in the optical filter 12
The front end portion 121 of the optical filter 12 is surrounded so as to be almost in close contact with it, thereby holding the optical filter 12.
Further, in the enlarged portion 134d, a gap is formed between the outer surface of the optical filter 12 and the groove 135d provided on the inner surface of the through hole 130 of the ferrule 13J. The hollow portion 242 of the flange 24 accommodates the portion of the optical filter 12 with the resin coating 115. Coating 1 of this optical filter 12
An adhesive 600 is filled between 15 and the hollow portion 242. The optical filter 12 is fixed in the hollow portion 242 by the adhesive 600.

In this optical connector, the grating 12
Of the light having the reflection wavelengths of 6, the light is emitted from the grating 126 to the clad 124, but enters the groove 135d. As a result, the emitted light from the grating 126 is less likely to travel forward and is gradually attenuated while being reflected in the groove 135d, so that light of the reflected wavelength of the grating 126 passes through the filter region 122. The power of light is reduced. Therefore, the optical connector of FIG. 69 has a high light blocking rate and can be suitably used as a constituent element of an inspection system of an optical line.

In the eleventh light shielding structure (third application example), the groove 135d is arranged so as to surround the entire grating 126, but the arrangement of the groove 135d is not limited to this. As shown in FIG. 11, the light emitted from the grating 126 to the cladding 124 travels obliquely forward from each part of the grating 126. Therefore, if the groove 135d is provided at a position diagonally forward of each part of the grating 126, the light blocking rate will be sufficiently increased.

FIG. 70 is a side sectional view showing a modification of the optical connector of FIG. 69 (corresponding to the sectional view taken along the line AA of FIG. 5).
It is. In this optical connector, the groove 135d is provided in front of the optical connector of FIG. 69 as a whole. As described above, the light emitted from the grating 126 to the cladding 124 travels obliquely forward of the grating 126. Therefore, if the enlarged portion 134d is provided obliquely forward of the tip of the grating 126, the grating 12
The emitted light from 6 will be sufficiently reduced. Therefore, the optical connector of FIG. 70 also has a sufficiently high light blocking rate, and can be suitably used as a component of an optical line inspection system.

[0232]

As described above, according to the optical connector (first to third light shielding structure) in the first embodiment of the present invention, the radiated light from the grating of the optical filter causes a gap between the optical filter and the flange. After advancing while leaking to, it is blocked by the end face of the ferrule. As a result, unnecessary radiation light from the grating is reduced, so that a high light blocking rate can be obtained.

Further, according to the optical connector having the fourth light shielding structure, when the optical fiber type optical filter is housed, the light emitted from the grating of the optical filter passes through the ferrule and is emitted to the outside. Therefore, it is possible to reduce the light that passes through the filter region and proceeds to the front of the grating, and increase the light blocking rate of the optical filter.

According to the optical connector having the fifth light shielding structure (first application example), the light emitted from the grating of the optical filter is absorbed by the ferrule, so that the light passes through the filter region and travels in front of the grating. It is possible to reduce the amount of light emitted and increase the light blocking rate of the optical filter. Further, according to the optical connector having the fifth light-shielding structure (second application example), the light emitted from the grating of the optical filter is absorbed by the light absorbing layer, so that the light passes through the filter region and reaches the front of the grating. It is possible to reduce the traveling light and increase the light blocking rate of the waveguide type optical filter.

According to the optical connector having the sixth light-shielding structure, of the light of the reflection wavelength of the grating, the light emitted from the grating is absorbed by the light absorbing material filled in the recess provided in the tip portion of the optical filter. Therefore, it is possible to reduce the light that passes through the grating and travels in front of the grating, and realizes a high light blocking rate.

According to the optical connector having the seventh light-shielding structure (first to third application examples), since the diameter of the light emission opening is smaller than the cladding outer diameter of the optical filter to be mounted, it is generated by the grating. However, the emitted light reaching the light emitting end face can be effectively shielded.

According to the optical connector having the eighth light shielding structure (first application example and second application example), when the optical filter is housed in the through hole of the ferrule, the light is emitted from the grating of the optical filter. Since the light passes through the opening (including the cutout or through hole) provided in the ferrule and is emitted to the outside, the light passing through the filter region and traveling in front of the grating is reduced, and the light of the optical filter is reduced. The blocking rate can be increased.

According to the optical connector having the ninth light shielding structure, the grating is 3 m from the light emitting end face of the optical filter.
Since they are formed at positions separated by m or more, the radiated light that travels from the core generated in the grating to the cladding side is
Since the light is repeatedly reflected by the outer surface of the clad or the inner surface of the through hole of the ferrule, the radiated light that reaches the light emitting end face of the optical filter is greatly reduced compared to when it is generated, and the light of the reflection wavelength determined by the grating pitch of the grating It is possible to realize an optical connector with a built-in filter that effectively shuts off the light.

According to the optical connector having the tenth light-shielding structure, when the optical filter is housed in the ferrule, the light emitted from the grating is blocked by the inner surface of the ferrule at the boundary between the enlarged portion and the standard portion. Therefore, the light blocking rate of the optical filter can be increased.

Further, according to the optical connector having the eleventh light shielding structure (first to third application examples), when the optical filter is housed in the ferrule, the light emitted from the grating is provided on the inner surface of the ferrule. As it progresses to the groove, it comes out from the tip of the ferrule,
When connecting to an optical component having a light receiving surface having a cross-sectional area similar to that of the above optical filter, the light blocking rate of the optical filter can be increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a first basic structure for optically coupling between optical fiber cables including a single optical fiber of an optical connector according to the present invention.

FIG. 2 is a diagram showing a second basic structure for optically coupling ribbon-type fiber cables including a plurality of optical fibers of the optical connector according to the present invention.

FIG. 3 is a diagram showing a third basic structure (optically coupling a transmission line and an optical element) of the optical connector according to the present invention.

FIG. 4 is a diagram showing a basic assembling process of the optical connector according to the present invention.

FIG. 5 is a front view showing the basic configuration of the entire optical connector according to the present invention.

FIG. 6 is a diagram showing a cross-sectional structure of a first embodiment of an optical connector according to the present invention (first light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

7 is a diagram showing the entire cross-sectional structure of a portion indicated by an arrow B1 of the optical connector shown in FIG. This cross section is
This corresponds to the cross section taken along the line BB of the optical connector shown in FIG.

FIG. 8 is a diagram showing a configuration of an apparatus for an experiment conducted by the inventors.

9 is a graph showing a result of an experiment performed by using the apparatus shown in FIG. 8 (amount of transmitted light (d
Bm) and the wavelength (nm) are shown).

10 is a graph showing a result of an experiment performed using the apparatus shown in FIG. 8 (showing a relationship between a transmitted light amount (dBm) and a wavelength (nm) when d = 500 mm).

FIG. 11 is a diagram for explaining the behavior of light propagating in the cladding region of the light to be reflected by the grating.

FIG. 12 is a view showing a cross-sectional structure of the first embodiment of the optical connector according to the present invention (second light-shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

13 is a diagram showing the entire cross-sectional structure of a portion indicated by an arrow B2 of the optical connector shown in FIG. This sectional view corresponds to the section taken along the line BB of the optical connector shown in FIG.

FIG. 14 is a diagram showing a cross-sectional structure of a first embodiment of an optical connector according to the present invention (third light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

15 is a diagram showing the entire cross-sectional structure of the portion shown by arrow B3 of the optical connector shown in FIG. This sectional view corresponds to the section taken along the line BB of the optical connector shown in FIG.

FIG. 16 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (first application example of fourth light-shielding structure and fifth light-shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

17 is a diagram showing the entire cross-sectional structure of the portion indicated by arrow C1 of the optical connector shown in FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 18 is a view showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (first application example of fourth light-shielding structure and fifth light-shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

FIG. 19 is a diagram showing the entire cross-sectional structure of the portion indicated by arrow C2 of the optical connector shown in FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 20 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (second of the fifth light shielding structure);
Application example). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

21 is a diagram showing the entire cross-sectional structure of a portion indicated by arrow C3 of the optical connector shown in FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 22 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (second application example of fifth light shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

23 is a diagram showing the entire cross-sectional structure of the portion indicated by arrow C4 of the optical connector shown in FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 24 is a perspective view showing the shape of the tip portion of the optical filter in the second embodiment of the optical connector according to the present invention.

FIG. 25 is a view showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (sixth light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

FIG. 26 is a view showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (sixth light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

27 is a drawing showing the entire cross-sectional structure of the portion of the optical connector shown in FIG. 26, which is shown by arrow C5. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 28 is a view showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (application example of sixth light-shielding structure).
This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

FIG. 29 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (first application example of seventh light-shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

30 is a front view of the optical connector shown in FIG. 29, as seen from the direction indicated by arrow E1. This figure corresponds to the front surface of the optical connector as seen from the direction indicated by the arrow E shown in FIG.

FIG. 31 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (second application example of seventh light-shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

32 is a front view of the optical connector shown in FIG. 31, as seen from the direction indicated by arrow E2. This figure corresponds to the front surface of the optical connector as seen from the direction indicated by the arrow E shown in FIG.

FIG. 33 is a view showing the cross-sectional structure of the second embodiment of the optical connector according to the present invention (the third application example of the seventh light-shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

34 is a front view of the optical connector shown in FIG. 33 as seen from the direction indicated by arrow E3. This figure corresponds to the front surface of the optical connector as seen from the direction indicated by the arrow E shown in FIG.

FIG. 35 is a view showing the overall structure of the plug in the second embodiment of the optical connector according to the present invention (first application example of eighth light shielding structure).

FIG. 36 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (first of the eighth light shielding structure);
Application example). This cross-sectional view is of the plug shown in FIG.
It corresponds to the cross section along the line F1-F1.

37 is an H1-H1 of the ferrule shown in FIG.
It is a figure showing the section along the line.

FIG. 38 is a G1-G1 of the ferrule shown in FIG.
It is a figure showing the section along the line.

FIG. 39 is a diagram for explaining how light in an optical fiber travels.

FIG. 40 is a diagram showing the overall structure of a second embodiment of the optical connector according to the present invention (first of the eighth light-shielding structure).
Application example).

41 is a view of H2-H2 of the optical connector shown in FIG.
It is a figure showing the section along the line.

FIG. 42 is a view showing the overall structure of the plug in the second embodiment of the optical connector according to the present invention (second application example of eighth light shielding structure).

FIG. 43 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (second of the eighth light shielding structure)
Application example). This cross-sectional view is of the plug shown in FIG.
It corresponds to the cross section along the line F2-F2.

FIG. 44 is an H3-H3 of the ferrule shown in FIG.
It is a figure showing the section along the line.

FIG. 45 is a view of the ferrule shown in FIG. 42, G2-G2.
It is a figure showing the section along the line.

FIG. 46 is a view showing the overall structure of the optical connector according to the second embodiment of the present invention (second of the eighth light shielding structure).
Application example).

47 is a view of the optical connector H4-H4 of FIG.
It is a figure showing the section along the line.

FIG. 48 is a drawing showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (ninth light-shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

49 is a view showing the front of the optical connector shown in FIG. 48, as seen from the direction shown by arrow E4. This figure corresponds to the front surface of the optical connector as seen from the direction indicated by the arrow E shown in FIG.

FIG. 50 is a diagram showing the configuration of an apparatus for measuring the wavelength dependence of the transmittance of an optical filter (optical filter in which a grating is not covered by a plug) not equipped with a connector.

51 is measured using the apparatus shown in FIG. 50,
It is a graph which shows the measurement result regarding the optical filter in which the connector is not attached.

FIG. 52 is a diagram showing a configuration of an apparatus for measuring wavelength dependency of a transmittance of an optical filter (optical filter in which a grating is covered with a plug) having a connector attached thereto.

53 is measured using the apparatus shown in FIG. 52,
It is a graph which shows the measurement result regarding the optical filter with which the connector was attached.

FIG. 54 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (the tenth light shielding structure).
This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

55 is a drawing showing the entire cross-sectional structure of the portion of the optical connector shown in FIG. 54, which is shown by arrow C6. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 56 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (tenth light-shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

57 is a diagram showing the entire cross-sectional structure of the portion indicated by arrow C7 of the optical connector shown in FIG. 56. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 58 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (the first application example of the eleventh light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

FIG. 59 is a diagram showing the entire cross-sectional structure of the portion indicated by arrow C8 of the optical connector shown in FIG. 58. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 60 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (first application example of eleventh light shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

61 is a drawing showing the entire cross-sectional structure of the portion indicated by arrow C9 of the optical connector shown in FIG. 60. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 62 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (the second application example of the eleventh light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

63 is an arrow C10 of the optical connector shown in FIG. 62;
It is a figure which shows the whole cross-section of the part shown by FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 64 is a diagram showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (second application example of eleventh light shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

65 is an arrow C11 of the optical connector shown in FIG. 64;
It is a figure which shows the whole cross-section of the part shown by FIG. This cross-sectional view corresponds to the cross section along the line CC of the optical connector shown in FIG.

FIG. 66 is a view showing the cross-sectional structure of the second embodiment of the optical connector according to the present invention (the second application example of the eleventh light-shielding structure in which the groove formation position is changed). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

FIG. 67 is a diagram showing a part of the assembling process of the second embodiment of the optical connector according to the present invention (the third application example of the eleventh light shielding structure). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

68 is an enlarged view of a main part of the ferrule shown in FIG. 67. FIG.

FIG. 69 is a view showing a cross-sectional structure of the second embodiment of the optical connector according to the present invention (the third application example of the eleventh light shielding structure). This sectional view is taken along line A of the optical connector shown in FIG.
-Corresponds to the cross section along line A.

FIG. 70 is a drawing showing a cross-sectional structure of a second embodiment of an optical connector according to the present invention (third application example of the eleventh light-shielding structure in which the groove formation position is changed). This cross-sectional view corresponds to the cross section taken along the line AA of the optical connector shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plug, 10 ... Optical connector (optical connector with a cord), 12, 12c ... Optical filter, 13, 13A-13
J ... Ferrule, 24 ... Flange, 115 ... Coating, 126 ... Grating, 121 ... Optical filter tip part, 122 ... Filter area, 241 ... Holding part, 24
2 ... Hollow part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 7-324746 (32) Priority date Hei 7 (1995) December 13 (33) Country of priority claim Japan (JP) (31) Priority Claim Number Japanese Patent Application No. 7-325720 (32) Priority Date No. 7 (1995) December 14 (33) Country of priority claim Japan (JP) (31) No. of priority claim Japanese Patent Application No. 7-325729 (32) Priority Hihei 7 (1995) December 14 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 7-327232 (32) Priority Day Hei 7 (1995) December 15 (33) ) Priority claiming country Japan (JP) (31) Priority claiming number Japanese Patent Application No. 8-13249 (32) Priority date Hei 8 (1996) January 29 (33) Priority claiming country Japan (JP) (72) Inventor Yoshiaki Miyajima 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Within Nippon Telegraph and Telephone Corporation (72) Inventor Shinichi Furukawa 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo No. within Nippon Telegraph and Telephone Corporation

Claims (33)

[Claims] 1. A waveguide structure comprising, as a part of a transmission line, a core having a predetermined refractive index and a clad having a lower refractive index than the core and covering the outer periphery of the core, An optical filter in which a grating for reflecting light of a predetermined wavelength is provided in a predetermined portion, and a tip having a space for housing a part of the optical filter and including one end face of the optical filter A plug attached to the optical filter in a state where the portion is housed in the space, wherein the grating is located at a tip portion of the optical filter and a portion housed in the space of the plug. Characteristic optical connector. 2. The light emitted from the grating to the clad among the light to be reflected by the grating, the one end surface of the optical filter being from a filter region of the optical filter provided with the grating. The optical connector according to claim 1, further comprising a light-shielding structure for blocking the propagation of light propagating toward the optical connector. 3. The plug has a through hole for accommodating a part of the optical filter, and the plug is attached to the optical filter with at least a part of a front end portion of the optical filter housed in the through hole. An attached ferrule and one end of the ferrule are attached, and a flange having a hollow portion for accommodating at least a portion of the distal end portion of the optical filter that is not accommodated in the through hole of the ferrule, The grating is located in a portion of the tip portion of the optical filter which is not housed in the through hole of the ferrule and is housed in the hollow portion of the flange. The optical connector described. 4. An adhesive having a refractive index substantially equal to or higher than that of the cladding of the optical filter is present in a space defined by the outer peripheral surface of the filter region of the optical filter and the inner wall of the hollow portion of the flange. The optical connector according to claim 3, wherein the optical connector is filled. 5. The space defined by the outer peripheral surface of the filter region of the optical filter and the inner wall of the hollow portion of the flange has a refractive index substantially equal to or higher than that of the cladding of the optical filter, and 4. The optical connector according to claim 3, wherein a tubular member surrounding the filter region is housed in a state where the optical filter is penetrated. 6. An adhesive having a refractive index substantially equal to or higher than that of the cladding of the optical filter is filled in at least a space defined by a filter region outer peripheral surface of the optical filter and an inner wall of the tubular member. The optical connector according to claim 5, wherein the optical connector is provided. 7. The optical connector according to claim 3, wherein, of the optical filter, at least an outer peripheral surface of a filter region of the optical filter is provided with a coating surrounding the grating. 8. The optical connector according to claim 7, wherein the coating has a refractive index substantially equal to or higher than that of the cladding of the filter. 9. The plug has a through hole for accommodating a part of the optical filter, and the plug is provided in the optical filter in a state where at least a part of a tip end portion of the optical filter is accommodated in the through hole. The optical connector according to claim 2, further comprising at least an attached ferrule, wherein the grating is located at a portion of the distal end portion of the optical filter, which is accommodated in a through hole of the ferrule. 10. The optical connector according to claim 9, wherein the ferrule is made of a transmissive material that transmits light having a wavelength matching the reflection wavelength of the grating. 11. The optical connector according to claim 10, wherein the transmissive material has a refractive index substantially equal to or higher than that of the cladding of the optical filter. 12. The ferrule absorbs light having a wavelength that matches a reflection wavelength of the grating, at least in a region of the light to be reflected by the grating, where the light reflected from the grating reaches the cladding. The optical connector according to claim 9, further comprising a light absorbing structure for 13. The optical connector according to claim 12, wherein the ferrule is made of a light absorbing material that absorbs light having a wavelength matching the reflection wavelength of the grating. 14. The inner wall of the through hole of the ferrule,
13. The optical connector according to claim 12, wherein a light absorption layer made of a material that absorbs light having a wavelength matching the reflection wavelength of the grating is formed. 15. A predetermined portion of a tip portion of the optical filter, which is accommodated in a through hole of the ferrule and to which light to be reflected by the grating reaches, is a remaining portion of the optical filter. The space defined by the outer peripheral surface of the predetermined portion of the optical filter and the inner wall of the through hole of the ferrule absorbs light having a wavelength matching the reflection wavelength of the grating. The optical connector according to claim 9, which is filled with an absorber. 16. The optical connector according to claim 15, wherein the light absorbing material has a refractive index substantially equal to or higher than that of the cladding of the optical filter. 17. The optical connector according to claim 9, wherein the plug is provided with a structure that limits a light emission opening at an end face of the optical filter to be smaller than a cross-sectional area of the optical filter. . 18. The opening of the through hole of the ferrule, which is located on the one end face side of the optical filter with respect to the grating, in the tip portion of the optical filter housed in the through hole of the ferrule, 18. The optical connector according to claim 17, wherein the optical connector is covered with a first light shielding member having an opening smaller than the one end surface of the optical filter. 19. The first opening of a through hole provided in the ferrule, which is located on the one end face side of the optical filter with respect to the grating, is on the side opposite to the first opening with respect to the grating. 18. The optical connector according to claim 17, which is smaller than the second opening of the through hole of the ferrule located. 20. A second light-shielding member having an opening smaller than a cross-sectional area of the optical filter is provided on the one end face of the optical filter housed in the through hole of the ferrule,
The optical connector according to claim 17, wherein the optical connector is attached in a state of being housed in the through hole of the ferrule. 21. The diameter of the limited light exit aperture of the optical filter is 1.1 of the mode field diameter of the optical filter.
The optical connector according to claim 17, wherein the optical connector is larger than four times and smaller than the outer diameter of the cladding of the optical filter. 22. The ferrule is radiated from the grating to the clad among the light to be reflected by the grating on the outer peripheral surface of the front end portion of the optical filter housed in the through hole of the ferrule. The optical connector according to claim 9, further comprising a structure for exposing a region where light reaches. 23. The ferrule has a notch extending from an outer peripheral surface of the ferrule to a through hole accommodating the optical filter, or a through hole connecting an outer surface of the ferrule with an inner wall of the through hole accommodating the optical filter. 23. The optical connector according to claim 22, further comprising a hole. 24. A refractive index matching material having a refractive index substantially the same as or higher than that of the cladding of the optical filter in the tip portion of the optical filter housed in the through hole of the ferrule. 24. The optical connector according to claim 23, which is covered with. 25. The grating located in the through hole of the ferrule is separated from the one end surface of the optical filter by 3 mm or more.
Optical connector as described. 26. The cross-sectional area of a region of the through-hole of the ferrule where the light emitted from the grating to the clad of the light to be reflected by the grating reaches a cross section of the optical connector with respect to the grating. The optical connector according to claim 9, wherein the optical connector has a larger opening cross-sectional area than the ferrule located on the one end face side. 27. A groove is provided on the inner wall of the through hole of the ferrule, and at least in a region of the light to be reflected by the grating, the light emitted from the grating to the cladding reaches. The optical connector according to claim 9, wherein: 28. The groove provided in the inner wall of the through hole of the ferrule has a second end facing the first end from the first end of the ferrule along the central axis of the through hole. 28. The optical connector according to claim 27, wherein the optical connector extends toward an end of the optical connector. 29. The light according to claim 27, wherein the groove provided on the inner wall of the through hole of the ferrule is formed along the circumferential direction of the cross section perpendicular to the central axis of the through hole. connector. 30. The groove provided in the inner wall of the through hole of the ferrule has a second end facing the first end from the first end of the ferrule with respect to the central axis of the through hole. The spirally extending shape toward the end.
7. The optical connector according to 7. 31. A space defined by an outer peripheral surface of a front end portion of the optical filter housed in a through hole of the ferrule and a groove provided on an inner wall of the through hole is provided in the space of the optical filter. 3. A refractive index matching material having a refractive index substantially equal to or higher than that of the clad is filled.
7. The optical connector according to 7. 32. The groove is provided in an inner wall of a through hole of the ferrule, which is located at least on the end face side of the optical filter distal end portion with respect to the grating except the end portion of the ferrule. 28. The optical connector according to claim 27, wherein: 33. The outer peripheral surface of the filter region of the optical filter is substantially covered with a single material member, and the longitudinal stress distribution in the filter region is uniform. The optical connector described.