JP4390270B2 - Optical fiber connection method and optical filter manufacturing method - Google Patents

Description

The present invention is useful in constructing an optical fiber transmission path, a method of manufacturing a connection side Ho及 beauty optical filter of the optical fiber.

  In recent years, in the field of information and communication, the demand for optical fiber transmission lines has been increasing in order to perform high-speed communication represented by the high-speed Internet, and in particular, the demand for optical fiber transmission lines in access systems has increased. Yes. FIG. 1 shows an example of an access system (optical access system) including an optical fiber transmission line.

  In the optical access system, the optical fiber transmission line 1 is an optical subscriber line terminator (Optical) installed between the telecommunications carrier's office 2 and the user's premises 3, more specifically, in the telecommunications carrier's office 2. Line Terminal (OLT) 4 and an optical subscriber line network device (ONU) 5 installed in the user's home 3 are arranged and connected, and optical signals (communication signals) between these devices ( Communication light) is transmitted and communication is performed.

  The optical access system includes an optical fiber transmission line test system that performs maintenance and various tests on the optical fiber transmission line 1. This is because the optical fiber transmission line 1 is remotely controlled by using an optical signal (test light) having a wavelength different from that of the communication light by an OTDR (optical pulse tester) 6 installed in the station 2. This is a system for detecting the position of breakage at the time of loss or breakage.

  Specifically, the test light from the OTDR 6 enters the optical fiber transmission line 1 through an optical component called an optical coupler 7 (see Patent Document 1) and propagates to the user home 3 side. Part of the test light that is being propagated becomes backscattered light, propagates in the reverse direction through the optical fiber transmission line 1, enters the OTDR 6 again via the optical coupler 7, and the loss of the optical fiber transmission line 1 is detected. The Further, when the optical fiber transmission line 1 is broken, the test light is reflected at the broken portion and returns to the OTDR 6, so that the position can be detected.

  The test light propagated to the user home 3 together with the communication light is provided by an optical filter 8 represented by an optical fiber Bragg grating (see Patent Document 2) provided in the vicinity of the ONU 5 in the user home 3 as shown in FIG. The reflected light is separated from the communication light, and only the communication light is incident on the ONU 5. Note that the above-described backscattered light and the test light that is reflected by the broken portion or the optical filter 8 and propagates in the reverse direction through the optical fiber transmission line 1 propagates to the OLT 4 side together with the OTDR 6 through the optical coupler 7. Since it is blocked by the optical filter 9 provided in the vicinity of the OLT 4, it does not enter the OLT 4.

As described above, since the test light and its reflected light do not enter the ONU 5 and the OLT 4, it is possible to maintain and test the optical fiber transmission line 1 even during communication.
Japanese Patent Laid-Open No. 5-127028 Japanese Patent Laid-Open No. 9-5544

  However, conventionally, in order to construct the above-described optical fiber transmission line, an optical coupler or an optical filter manufactured in advance as an optical component at a factory or the like is necessary, and a connection work using a fusion or the like or a connection work using a connector or the like Must be performed between the optical coupler, the optical filter, and the optical fiber in addition to the original connection point associated with the construction of the optical fiber transmission path between the OLT or ONU and the optical fiber, which increases the cost. At the same time, there is a problem that it takes time and effort to work, and it is impossible to immediately respond to the request from the user.

  In the future, in order to respond to the rapid increase in the number of optical access systems, especially the construction of optical access systems equipped with the optical fiber transmission line test system described above, the construction of optical fiber transmission lines will further reduce costs and work. Simplification and prompt response to user requests are eagerly desired.

An object of the present invention is to provide an optical fiber transmission line capable of arbitrarily combining, branching or reflecting optical signals, which is simpler and more economical than conventional ones, and can be quickly constructed in response to user demands. It is to provide a method of manufacturing a connection side Ho及 beauty optical filter fiber.

In the present invention, in order to solve the above-described problem, at least two optical fibers are arranged so that their one ends are substantially opposed to each other with a gap therebetween, and the refractive index after curing and the curing start wavelength are different from each other. A mixed solution containing different types of photocurable resins is interposed between one end of each of the optical fibers, and at least two types of light sources are used to cure the photocurable resin in the mixed solution to provide a core portion and a cladding. parts, and forming a grating portion in addition to this.

According to the present invention, since the connection and simultaneous optical fibers can create an optical filter to the connection portion, to build arbitrarily optical signal coupling or branch or reflection through the optical fiber transmission line capable easily and economically be able to. In addition , time for procuring optical components such as an optical filter is not necessary, and it is possible to respond immediately when there is a request for construction of an optical fiber transmission line from a user.

<Embodiment 1>
FIGS. 3 to 6 show an embodiment of the present invention, where four optical fibers are connected and a 2 × 2 coupler is formed at the connecting portion (however, not included in the scope of claims) In the figure, 11 is a mixed solution of a photocurable resin, 12 is a container for storing the mixed solution 11, 13-1, 13-2, 13-3, 13-4 are optical fibers, Reference numerals 14-1, 14-2, 14-3, and 14-4 denote a light source e for forming a core portion, and 15 denotes a light source f for forming a cladding portion.

  The photo-curable resin mixed solution 11 is composed of two types of photo-curing resins in which the refractive index after curing and the curing start wavelength are adjusted, here the core of the optical fiber connecting the refractive index after curing and the curing start wavelength, respectively. The refractive index of the clad of the optical fiber that connects the first photocurable resin adjusted to the refractive index and the wavelength of the light source e for forming the core part, and the refractive index and the curing start wavelength after curing, respectively, for forming the clad part It is a mixed solution with the second photocurable resin adjusted to the wavelength of the light source f, and is prepared in advance.

  First, the optical fibers 13-1 to 13-4 are arranged in such a manner that one end to be connected has a predetermined positional relationship as shown in FIG.

  Specifically, the optical fibers 13-1 and 13-2 are arranged so that the respective one ends thereof are substantially opposed to each other with a gap and the respective central axes are parallel and do not coincide with each other, and the optical fibers 13-3 are arranged. One end of the optical fiber 13-1 is substantially opposed to the optical fiber 13-1 with a gap therebetween, and the central axis is not parallel to the central axis of the optical fiber 13-1, and the extension of the central axis is the optical fiber 13. The optical fiber 13-4 is arranged so as to intersect with the extension line of the central axis of -1, and one end of the optical fiber 13-4 is substantially opposed to the optical fiber 13-2 with a gap therebetween, and the central axis is the optical fiber. It is arranged so that it is not parallel to the central axis of 13-2 and the extension of the central axis intersects the extension of the central axis of the optical fiber 13-2.

  Here, although the optical fibers 13-3 and 13-4 are drawn substantially parallel in the drawing, they are not necessarily parallel.

  Each optical fiber 13-1 to 13-4 is held by holding means (not shown), and the above-described arrangement relationship is maintained until the end of the connection work. Moreover, the relationship of the central axis between each optical fiber mentioned above should just be maintained in the vicinity of one end which should be connected, and it does not need to be in such a relationship in the whole length of each optical fiber. Needless to say, this point is common to all embodiments of the present invention.

  Next, the mixed solution 11 of the photocurable resin is injected into the container 12, and this is interposed between one ends of the optical fibers 13-1 to 13-4.

  Next, only the light sources (e) 14-1 and 14-2 connected to the other ends of the optical fibers 13-1 and 13-2 are operated, and light having a wavelength for forming the core portion is incident from the other ends. . Then, the light of the wavelength for core part formation is radiate | emitted in the mixed solution 11 from the end (core part) of the optical fibers 13-1 and 13-2, and, thereby, the 1st photocurable resin in the mixed solution 11 As shown in FIG. 4, the waveguides (core portions) 16-1 and 16-2 extend from the ends of the optical fibers 13-1 and 13-2 along the extension lines of the respective cores. Is formed. Thereafter, when the waveguides 16-1 and 16-2 reach predetermined positions (intersection positions), the operations of the light sources 14-1 and 14-2 are stopped.

  Next, only the light source (e) light sources 14-3 and 14-4 connected to the other ends of the optical fibers 13-3 and 13-4 are operated, and light having a wavelength for forming the core portion is incident from the other ends. To do. Then, similarly to the above, light having a wavelength for forming the core part is emitted into the mixed solution 11 from one end (the core part) of the optical fibers 13-3 and 13-4, whereby the first light in the mixed solution 11 is emitted. Only the photocurable resin reacts and cures, and as shown in FIG. 5, the waveguide (core part) 16-3 extends from one end of each of the optical fibers 13-3 and 13-4 along the extension line of each core. And 16-4 are formed. Thereafter, when the waveguides 16-3 and 16-4 reach the tips of the waveguides 16-1 and 16-2 from the previously formed optical fibers 13-1 and 13-2, respectively, the light source 14-3 And 14-4 are stopped, the waveguides 16-1 and 16-3 are connected, and the waveguides 16-2 and 16-4 are connected.

  Finally, when the light source (f) 15 is operated and light having a wavelength for forming a clad portion is irradiated between one end of each optical fiber, only the second photocurable resin in the mixed solution 11 reacts. Curing (especially the second photo-curing resin around the waveguides 16-1 to 16-4 reacts and cures earlier) forms a clad portion 17 as shown in FIG.

  Here, the length l of the adjacent portions of the two waveguides 16-1 and 16-2 parallel to each other is a coupling length that determines the branching ratio of the optical coupler. Therefore, a desired branching ratio can be obtained by designing the coupling length l according to the required branching ratio and arranging each optical fiber.

  In this embodiment, the 2 × 2 coupler has been described. However, optical couplers having various shapes such as 1 × 2, 3 × 3, and 4 × 4 are created by adjusting the number of optical fibers to be connected depending on applications. be able to.

  FIG. 7 shows a modification of the first embodiment of the present invention, in which an example in which three optical fibers are connected and a 1 × 2 coupler is formed at the connection portion is shown. In the figure, the same components as in FIGS. 3 to 6 are denoted by the same reference numerals, 11 is a mixed solution of a photocurable resin, 13-1 to 13-3 are optical fibers, and 14-1 to 14-3 are cores. The light source e for forming the part, 15 is the light source f for forming the clad part, and 16-1 to 16-3 are the waveguides (core part).

  Here, the state where the formation of the waveguide (core portion) is completed, that is, the same state as in FIG. 5 described above, is shown, but the fourth optical fiber and the waveguide (core portion) formed from one end thereof are shown. This is the same as in the first embodiment, including the manufacturing process, except that the corresponding light source (e) is not necessary.

  FIG. 8 shows another modification of the first embodiment of the present invention, here, an example in which 8 optical fibers are connected and a 4 × 4 coupler is formed at the connection portion. In the figure, the same components as those in FIGS. 3 to 6 are denoted by the same reference numerals, 11 is a mixed solution of a photocurable resin, 13-1 to 13-8 are optical fibers, and 14-1 to 14-8 are cores. The light source e for forming the part, 15 is the light source f for forming the cladding part, and 16-1 to 16-8 are the waveguides (core part).

  Here, the state where the formation of the waveguide (core portion) is completed, that is, the same state as in FIG. 5 described above is shown, but the optical fiber 13-5 parallel to the optical fiber 13-1, the optical fiber 13-2, The parallel optical fiber 13-6, the optical fiber 13-7 whose extension of the central axis intersects the extension of the central axis of the optical fiber 13-5, and the extension of the central axis is the central axis of the optical fiber 13-6 And an optical fiber 13-8 intersecting with the extended line of the optical waveguide 13 and waveguides (core portions) 16-5 to 16-8 formed from one end thereof, and light sources (e) 14-5 corresponding to these are added. Except for the point that 14-8 is necessary, it is the same as the case of the first embodiment including the manufacturing process.

  Here, the optical fibers 13-1 to 13-8 are arranged so that the waveguides 16-1, 16-2, 16-5, and 16-6 parallel to each other are arranged three-dimensionally. This is because the coupling states (intervals) between the waveguides 16-1, 16-2, 16-5, and 16-6 are made as equal as possible.

<Embodiment 2>
FIG. 9 to FIG. 11 show an embodiment of the present invention, in which two optical fibers are connected and an optical filter (here, an optical fiber Bragg grating) is formed in the connecting portion (however, the claims In the figure, 21 is a mixed solution of a photocurable resin, 22 is a container for storing the mixed solution 21, 23-1, 23-2 are optical fibers, 24 is The light source e for forming the core part, 25 is the light source f for forming the clad part, 26 is the light source g for forming the grating part, and 27 is a mask.

  The mixed solution 21 of the photocurable resin includes three types of photocurable resins in which the refractive index after curing and the curing start wavelength are adjusted, here, the core of the optical fiber connecting the refractive index after curing and the curing start wavelength, respectively. The refractive index of the clad of the optical fiber that connects the first photocurable resin adjusted to the refractive index and the wavelength of the light source e for forming the core part, and the refractive index and the curing start wavelength after curing, respectively, for forming the clad part Refraction higher than the core of the optical fiber connecting the second photo-curing resin adjusted to the wavelength of the light source f and the refractive index after curing and the curing start wavelength (so that light of a specific wavelength is reflected) It is a mixed solution with the third photo-curing resin adjusted to the wavelength and the wavelength of the light source g for forming the grating part, and is prepared in advance.

  First, the optical fibers 23-1 and 23-2 are arranged so that the ends to be connected are opposed to each other with a gap and the respective central axes coincide with each other in the container 22 as shown in FIG. 9. .

  Next, the mixed solution 21 of the photocurable resin is injected into the container 22 and interposed between the one ends of the optical fibers 23-1 and 23-2.

  Next, the light source (e) 24 connected to one of the optical fibers 23-1 and 23-2, here, the other end of the optical fiber 23-1, is operated, and light having a wavelength for forming the core portion is formed from the other end. Is incident. Then, the light of the wavelength for core part formation is radiate | emitted in the mixed solution 21 from the end (core part) of the optical fiber 23-1, and only 1st photocurable resin in the mixed solution 21 reacts by this. As shown in FIG. 10, a waveguide (core portion) 28 is formed from one end of the optical fiber 23-1 to one end of the optical fiber 23-2 along the extension line of the core.

  At this time, the light source (g) 26 is operated before the waveguide 28 is completely cured, and light having a wavelength for forming the grating portion is formed between the one ends of the optical fibers 23-1 and 23-2 in a predetermined pattern ( When irradiated through a mask 27 having a grating pattern), only the third photocurable resin in the mixed solution 21 (in the waveguide 28) reacts and cures, and as shown in FIG. A portion 28 a having a higher refractive index than that of the waveguide 28 is formed in 28.

  Finally, when the light source (f) 25 is operated to irradiate light having a wavelength for forming the cladding portion between the one ends of the optical fibers 23-1 and 23-2, the second photocurability in the mixed solution 21 is obtained. Only the resin reacts and cures (in particular, the second photo-curing resin around the waveguide 28 reacts and cures earlier), and a clad portion 29 as shown in FIG. 11 is formed.

  Here, the characteristics of the produced fiber Bragg grating can be freely set by changing the length of the waveguide 28 irradiated by the light source (g) 26 or the pattern interval on the mask 27.

<Embodiment 3>
FIGS. 12 to 14 show another example of Embodiment 3 of the present invention, in which two optical fibers are connected and an optical filter (here, an optical fiber Bragg grating) is formed at the connection portion. In the figure, 31 is a mixed solution of a photocurable resin, 32 is a container for storing the mixed solution 31, 33-1, 33-2 are optical fibers, 34 is a light source e for forming a core part, and 35 is a cladding part. The light sources f and 36 for forming are light sources h and 37 for forming a grating part, and are optical couplers.

  The mixed solution 31 of the photocurable resin includes three types of photocurable resins in which the refractive index after curing and the curing start wavelength are adjusted, here, the core of the optical fiber that connects the refractive index after curing and the curing start wavelength, respectively. The refractive index of the clad of the optical fiber that connects the first photocurable resin adjusted to the refractive index and the wavelength of the light source e for forming the core part, and the refractive index and the curing start wavelength after curing, respectively, for forming the clad part Refraction higher than the core of the optical fiber connecting the second photo-curing resin adjusted to the wavelength of the light source f and the refractive index after curing and the curing start wavelength (so that light of a specific wavelength is reflected) It is a mixed solution with a third photo-curing resin adjusted to the rate and the wavelength of the light source h for forming the grating portion, and is prepared in advance.

  First, the optical fibers 33-1 and 33-2 are arranged such that one end to be connected in the container 32 is opposed to each other with a gap and the respective central axes coincide with each other as shown in FIG. .

  Next, the mixed solution 31 of the photo-curable resin is injected into the container 32, and this is interposed between one ends of the optical fibers 33-1 and 33-2.

  Next, the light source (e) 34 and the light source (h) 36 connected to either one of the optical fibers 33-1 and 33-2, here the other end of the 33-1, using the optical coupler 37 are operated, From the other end, light having a wavelength λ1 for forming a core portion and light having a wavelength λ2 for forming a grating portion are incident alternately, that is, so as to be pulsed light having phases opposite to each other. Then, the light having the wavelength λ1 for forming the core part and the light having the wavelength λ2 for forming the grating part are alternately emitted from one end (the core part) of the optical fiber 33-1 into the mixed solution 31. Only the first photocurable resin and the third photocurable resin in the reaction react and cure alternately, and light is transmitted from one end of the optical fiber 33-1 along the extension line of the core as shown in FIG. A waveguide (core portion) 38 and a portion 38 a having a higher refractive index than the waveguide 38 are formed in the waveguide 38 and the waveguide 38 up to one end of the fiber 33-2.

  Finally, when the light source (f) 35 is operated to irradiate light having a wavelength for forming the cladding portion between the one ends of the optical fibers 33-1 and 33-2, the second photocurability in the mixed solution 31 is obtained. Only the resin reacts and cures (in particular, the second photo-curing resin around the waveguide 38 reacts and cures earlier), and a clad portion 39 as shown in FIG. 14 is formed.

  Here, the characteristics of the fiber Bragg grating produced by adjusting the distribution of light of wavelength λ1 and light of wavelength λ2 (repetition interval and duty ratio of pulsed light) by the light source (e) 34 and light source (h) 36. Can be set freely.

Configuration diagram showing an example of an access system including an optical fiber transmission line Explanatory drawing showing test light reflected and returned by an optical filter near the ONU The block diagram which shows Embodiment 1 of this invention Manufacturing process diagram showing Embodiment 1 of the present invention Manufacturing process diagram showing Embodiment 1 of the present invention Manufacturing process diagram showing Embodiment 1 of the present invention The block diagram which shows the modification of Embodiment 1 of this invention The block diagram which shows the other modification of Embodiment 1 of this invention The block diagram which shows Embodiment 2 of this invention Manufacturing process diagram showing Embodiment 2 of the present invention Manufacturing process diagram showing Embodiment 2 of the present invention The block diagram which shows Embodiment 3 of this invention Manufacturing process diagram showing Embodiment 3 of the present invention Manufacturing process diagram showing Embodiment 3 of the present invention

Explanation of symbols

  1: optical fiber transmission line, 2: carrier's office, 3: user's house, 4: optical subscriber line termination unit (OLT), 5: optical subscriber line network unit (ONU), 6: optical pulse test Machine (OTDR), 7: optical coupler, 8: optical filter (optical fiber Bragg grating), 9: optical filter, 11, 21, 31: mixed solution of photocurable resin, 12, 22, 32: container, 13- 1-13-8, 23-1, 23-2, 33-1, 33-2: optical fiber, 14-1 to 14-8, 24, 34: light source e, 15, 25, 35 for forming the core part : Light source f for forming clad part, 16-1 to 16-8, 28, 38: Waveguide (core part), 28a, 38a: Parts having higher refractive index than waveguide, 17, 29, 39: Cladding part , 26: light source g for forming a grating part, 27: mask, 3 : Light source h of grating portion formation, 37: optical coupler.

Claims (2)

A method of connecting two optical fibers,
Two optical fibers are arranged so that each one end faces each other with a gap and the respective central axes coincide with each other.
A first photo-curable resin in which the refractive index after curing and the curing start wavelength are adjusted to the refractive index of the core of the optical fiber and the wavelength of the light source for forming the core part, respectively, and the refractive index and curing start wavelength after curing, respectively. The second photo-curing resin adjusted to the refractive index of the clad of the optical fiber and the wavelength of the light source for forming the clad portion, and the refractive index and the grating after the curing are higher than the core of the optical fiber, respectively. Interposing a mixed solution with the third photocurable resin adjusted to the wavelength of the light source for forming the part between one end of each optical fiber,
The light from the light source for forming the core part and the light source for forming the grating part are alternately incident on the other end of any one of the optical fibers, and the first photocurable resin and the third photocured resin in the mixed solution. The core portion and the portion having a higher refractive index than the core portion are simultaneously formed between the two optical fibers by alternately curing the resin.
An optical fiber characterized in that a clad part is formed by irradiating light from a light source for forming a clad part between one end of each optical fiber to cure the second photocurable resin in the mixed solution. Connection method. A method of manufacturing an optical filter at a connection site between two optical fibers,
Two optical fibers are arranged so that each one end faces each other with a gap and the respective central axes coincide with each other .
First photocurable resin adjusted refractive index after hardening and curing start wavelength to the wavelength of the refractive index and the light source for forming a core part of the core of each optical fiber, the refractive index and curing initiation wavelength after curing A second photo-curing resin adjusted to the refractive index of the cladding of the optical fiber and the wavelength of the light source for forming the cladding, respectively, and the refractive index after curing and the curing start wavelength are higher than the refractive index of the core of the optical fiber and A mixed solution with a third photocurable resin adjusted to the wavelength of the light source for forming the grating part is interposed between one end of each optical fiber,
The light from the light source for forming the core part and the light source for forming the grating part are alternately incident on the other end of any one of the optical fibers, and the first photocurable resin and the third photocured resin in the mixed solution. than core portion and the core portion between the sexual resin cured alternately two optical fibers to form a high refractive index portion at the same time,
Light and forming a second clad portion by curing the photocurable resin in the mixed solution was irradiated with light from a light source for the clad portion formed between the one ends of the optical fibers A method for manufacturing a filter.

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