JP2001147341A - Optical circuit module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical circuit module which is smaller in size, for which a small mounting space are sufficient and of which the structure is easily manufactured. SOLUTION: This module is such that, on a module main shaft Ms forming a straight line, a double-core ferrule 20 with two parallel coated optical fibers 2a, 7a and a single core ferrule 9 with one coated optical fiber 4a being arranged nearly coapially, and that the tip end faces of these ferrules 20, 9 oppositely face each other at a prescribed space apart. A first collimator lens 21 corresponding to the tip end face of the double core ferrule 20, a second collimator lens 12 corresponding to the tip end face of the single core ferrule 9, and an optical multiplex/demultiplex filter 22 and a wedge glass plate 23 that is interposed between the first and second collimator lenses 21, 12 are arranged serially on the module main shaft Ms, at the space at the tip end faces of the ferrules 20, 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical circuit module which is a component of an optical fiber communication system and the like.
In particular, the present invention relates to an optical circuit module interposed between three optical fibers to multiplex or demultiplex light of a plurality of systems having different wavelengths.

[0002]

2. Description of the Related Art As is well known, some types of optical fiber communication systems use an optical fiber amplifier having the configuration shown in FIG. As shown in FIG.
The signal light having a wavelength of 1.55 μm to be introduced into in propagates through the optical isolator 1 to the erbium-doped optical fiber 2. The signal light passes through the optical multiplexing / demultiplexing circuit 3 from the erbium-doped optical fiber 2, propagates to the optical fiber 4, passes through the optical isolator 5, and reaches the output port Pout.

On the other hand, an excitation light source 6 composed of a semiconductor laser generates excitation light having a wavelength of 1.48 μm. The pumping light propagates through the optical fiber 7 and is introduced into the optical multiplexing / demultiplexing circuit 3, from which it propagates through the erbium-doped optical fiber 2 in a direction opposite to the signal light. The signal light (wavelength 1.55 μm) propagating through the erbium-doped optical fiber 2 is amplified by the pump light (wavelength 1.48 μm) traveling in the opposite direction.

Since the traveling direction of the pump light and the traveling direction of the signal light are opposite to each other, this type is called a backward pumping type optical fiber amplifier. A forward-pumped optical fiber amplifier in which the traveling directions of the pump light and the signal light are the same, and a bidirectional pump-type optical fiber amplifier in which the backward and forward pumping types are combined are well known. Have been.

In the backward pumping type optical fiber amplifier shown in FIG. 1, the optical multiplexing / demultiplexing circuit 3 is configured as shown in FIG. The optical multiplexing / demultiplexing circuit module includes a ferrule 8 including the core 2a of the optical fiber 2, a ferrule 9 including the core 4a of the optical fiber 4, and a ferrule 10 including the core 7a of the optical fiber 7. Collimating lenses 11, 12, 13 arranged on the optical axis of each of the ferrules 8, 9, 10;
An optical multiplexing / demultiplexing filter (also referred to as “WDM”) 14 is provided between the optical axes of these three lenses.

Here, the optical multiplexing / demultiplexing filter 14 is formed by forming a dielectric multilayer film on a glass plate, and this is combined with three ferrules 8, 9, 10 and a collimating lens 11,
The following optical path is formed by the optical positional relationship between the optical fibers 12 and 13. The signal light having a wavelength of 1.55 μm emitted from the optical fiber core 2a of the amplifying system and passed through the lens 11 is transmitted through the optical multiplexing / demultiplexing filter 14, collected by the lens 12, and introduced into the optical fiber core 4a of the output system. You. Excitation light having a wavelength of 1.48 μm emitted from the optical fiber core wire 7a and passing through the lens 13 is reflected by the optical multiplexing / demultiplexing filter 14, collected by the lens 11, and introduced into the optical fiber core wire 2a of the amplification system. .

[0007]

The above-described application is one form of the prior art to which the present invention is applied. However, the conventional optical multiplexing / demultiplexing circuit module having the configuration shown in FIG. 2 has a problem that miniaturization is difficult. In this module, three ferrules 8, 9, and 10 are mounted so as to penetrate a case (not shown). The case includes three collimating lenses 11, 12, and 13, and an optical multiplexing / demultiplexing filter 14. Is built-in. Then, the optical fibers 2, 4, and 7 are drawn out of the case to the outside.

Here, the ferrule 8 (optical fiber core wire 2a) and the ferrule 9 (optical fiber core wire 4a) optically coupled in the transmission optical path of the optical multiplexing / demultiplexing filter 14 are substantially co-linear as shown in FIG. It becomes a side-by-side arrangement. On the other hand, the ferrule 8 (the optical fiber core 2a) and the ferrule 10 that are optically coupled in the reflection optical path of the optical multiplexing / demultiplexing filter 14
The (optical fiber core wire 7a) is attached to the case at an angle of about 20 ° to 90 ° with respect to the axial form formed by the ferrule 8 and the ferrule 9.

For this reason, the ferrule 10 has an arrangement relationship in which the ferrule 10 protrudes largely to the side with respect to the main axis formed by the arrangement of the ferrule 8 and the ferrule 9. That is, the fiber 4 and the fiber 7 have a case-shaped configuration.
In addition, since the collimating lens 11 for the ferrule 8 and the collimating lens 13 for the ferrule 10 are required, the internal dimensions of the case are also increased. Therefore, the size of the entire case is increased, the optical fiber 4 and the optical fiber 7 are attached in a C-shape, and the mounting space is increased.

Further, as described above, when the ferrule is to be mounted obliquely at a predetermined angle, it is necessary to adjust the front-back direction along the optical path for adjusting the focal position and to adjust the angle. The assembling / adjustment process becomes very complicated as compared with the one. That is, in the example shown in FIG. 2, the adjustment between the ferrules 8 and 9 can be performed relatively easily, but the angle adjustment of the ferrule 10 which is mounted obliquely becomes very complicated. If the angle or the like deviates, desired characteristics cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and has as its object to solve the above-mentioned problems, to be smaller and to have a smaller mounting space, and to be easily mounted and assembled. It is an object of the present invention to provide an optical circuit module which can be manufactured easily by reducing the number of parts and can reduce costs.

[0012]

In order to achieve the above object, the optical circuit module of the present invention is a three-port type module, and has a basic module layout having two parallel optical fiber cores. Core ferrule,
A one-core ferrule having one optical fiber core wire;
The two ferrules are disposed substantially coaxially on the main axis of the straight module, and the end faces of both ferrules face each other at a predetermined interval. Further, a first collimating lens facing the distal end surface of the two-core ferrule, a second collimating lens facing the distal end surface of the single-core ferrule, and an optical system interposed between the first and second collimating lenses. A wave splitter filter and a wedge plate (“wedge glass plate” in the embodiment) are arranged in series on the module main shaft at a space between the tip surfaces of the two ferrules. The core of the one-core ferrule and one of the cores of the two-core ferrule are optically coupled in the transmission optical path of the optical multiplexing / demultiplexing filter, and the two cores of the two-core ferrule are connected to the optical multiplexing / demultiplexing filter. It creates an optical arrangement that optically couples in the reflected light path.

Then, a dielectric multilayer film as the optical multiplexing / demultiplexing filter is formed on the surface of the wedge plate, and these can be integrated.

Here, the optical multiplexing / demultiplexing filter referred to in the present invention is a WDM (Wavelength Division Multiplexer / Demultiplexer).
Multiplexer) is an optical component that combines or separates light of different wavelengths. In other words, a function of discriminating wavelengths from light containing several different wavelengths and outputting the light to each determined terminal (demultiplexing function), and inputting light of several wavelengths from different terminals. Function to emit light containing these wavelengths from one terminal (combining function)
Of these, an optical component having at least one function. Therefore, although the term "optical multiplexing / demultiplexing filter" is used, the concept is not limited to a filter having a multiplexing function and a demultiplexing function, but includes a filter having only a multiplexing function or only a demultiplexing function.

A wedge plate (prism for bending an optical path), which is a component constituting a main part of the present invention, is made of an isotropic medium such as a glass plate, and finally each ferrule is parallel to the module axis. This means that the optical path of the passing light is appropriately bent for the incoming and outgoing light as follows. When focusing only on the wedge plate, one of the incident light and the outgoing light to the wedge plate is, in principle, parallel to the module main axis.

In the present invention, the one-core ferrule and the two-core ferrule
The core ferrule and the core ferrule are arranged on a substantially straight line. Further, since the two fiber cores included in the two-core ferrule are very close to each other, the two cores can be handled by a common collimating lens.

Further, in order to perform the optical multiplexing and the optical demultiplexing, it is necessary to provide a predetermined opening angle in the optical path of the two lights. In the present invention, the axis of each core of the two-core ferrule is set to the axis of the collimating lens. Even if the ferrules arranged at positions shifted from the optical axis are arranged on a straight line, the exchangeable optical paths are separated due to the angle between the two optical paths incident and emitted from the two cores, and Light combining / spectral processing is performed.

Since the wedge plate is provided, the optical path of the light passing between the two ferrules is bent at an appropriate angle.
The light becomes parallel to the module main axis, and the light entering and exiting both ferrules becomes parallel to the module main axis. That is, since the ferrule can be placed in parallel with the module main axis, the angle between the two ferrules is 0 degree. That is, they are arranged in the same straight line or parallel even if they are shifted. Therefore, when the two ferrules are mounted on the cylindrical case, they can be easily assembled, and the mounting position and the angle can be easily adjusted.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical circuit module of the present invention can be applied to optical circuits having various configurations for various purposes, and the gist of the present invention will be described based on some specific examples described below. Of course, it should not be construed as limiting. In the following, in order to explain the embodiment of the present invention easily, FIG. 2 mainly shows an example corresponding to the optical multiplexing / demultiplexing circuit 3 in the backward pumping type optical fiber amplifier shown in FIG. This will be described in comparison with the conventional module configuration.

FIG. 3 shows an optical circuit module according to a first embodiment of the present invention. This is a three-port module. As a basic module layout, a two-port module having two parallel optical fiber cores 2a and 7a is used.
A core ferrule 20 and a single-core ferrule 9 having one optical fiber core wire 4a are disposed substantially coaxially on a single linear module main axis Ms. They face each other at intervals.

A first collimating lens 21 facing the distal end face of the two-core ferrule 20 and a one-core ferrule 9
A second collimating lens 12 facing the front end face of the optical fiber, an optical multiplexing / demultiplexing filter 22 and a wedge glass plate 2 interposed between the first and second collimating lenses 21 and 12.
3 are arranged in series on the module main shaft Ms at the space between the end faces of the two ferrules 20 and 9.

The core wires 4a and 2 of the one-core ferrule 9
One of the cores 2 a of the core ferrule 20 is optically coupled with the transmission optical path of the optical multiplexing / demultiplexing filter 22, and the two cores 2 a and 7 a of the two-core ferrule 20 are optically coupled with the reflection optical path of the optical multiplexing / demultiplexing filter 22. To create optical relationships.

In FIG. 3, one core 2a of the two-core ferrule 20 is connected to the erbium-doped optical fiber 2 for amplification in FIG. 1, and the other core 7a of the two-core ferrule 16 is an excitation optical fiber in FIG. The core wire 4a of the one-core ferrule 9 is connected to the optical fiber 4 of the output system in FIG.

The optical multiplexing / demultiplexing filter 22 is formed by forming a dielectric multilayer film on a glass plate.
Is made of a glass plate whose front and back planes form a predetermined angle that is not parallel. The following optical path is formed by the optical positional relationship between the optical multiplexing / demultiplexing filter 22 and the wedge glass plate 23, the two-core ferrule 20, the one-core ferrule 9, and the collimating lenses 21 and 12.

That is, the signal light having a wavelength of 1.55 μm emitted from the optical fiber core wire 2a of the amplification system and having passed through the collimating lens 21 is transmitted through the optical multiplexing / demultiplexing filter 22, and travels in a wedge glass plate 23 at a predetermined angle. The light is bent, condensed by the collimator lens 12, and introduced into the optical fiber core wire 4a of the output system. Excitation light having a wavelength of 1.48 μm emitted from the optical fiber core wire 7a and passing through the collimating lens 21 is reflected by the optical multiplexing / demultiplexing filter 22, collected by the same lens 21, and introduced into the optical fiber core wire 2a of the amplification system. Is done.

Also, as shown in FIG.
The collimating lens 21, the optical multiplexing / demultiplexing filter 22, the wedge glass plate 23, the collimating lens 12, and the single-core ferrule 9 are arranged almost in the same straight line on the module main axis Ms forming one straight line. Due to the arrangement relationship, the whole is housed in one cylindrical case (not shown). Two optical fibers 2 and an optical fiber 7 are drawn in parallel from one end of the cylindrical case, and one optical fiber 4 is drawn from the other end of the cylindrical case.

With such a module configuration, the outer shape of the case becomes a simple cylindrical shape as compared with the module configuration of the conventional configuration shown in FIG. Further, since the two optical fiber cores 2a and 7a included in the two-core ferrule 20 are very close to each other, the two optical fiber cores 2a and 7a can be handled by the common collimating lens 21. This also contributes to downsizing of the module case.

The above-mentioned feature that the module case has a simple cylindrical shape is that an appropriate wedge glass plate 23 is provided in the optical path connecting the collimating lenses 21 and 12, and the optical path is appropriately bent. It was realized by. By appropriately utilizing the optical path bending effect of the wedge glass plate 23, each optical component (two-core ferrule 20, collimating lens 21, optical multiplexing / demultiplexing filter 22, wedge glass plate 23, collimating lens 12) is used.
The single-core ferrule 9) can be arranged almost in a straight line on the module main axis Ms forming one straight line.

That is, as shown in FIG. 4, if the refractive index of the wedge glass plate 23 is n and the apex angle shown in FIG. , As shown in the following equation. sin θ ₂ = n ·
sin (E + sin ⁻¹ (sin θ ₁ / n)) Therefore, in the present embodiment, the apex angle E is set so that the emission angle θ2 = 0 when the angle (θ1) is inclined with respect to the module main axis Ms. Accordingly, the optical components can be arranged side by side on the module main axis Ms almost linearly.

The fact that the module case can be formed into a simple cylindrical shape means that the module case can be easily manufactured, and the optical components (two-core ferrule 20, collimating lens 21, optical multiplexing / demultiplexing filter 22, This means that the structure for mounting the wedge glass plate 23, the collimating lens 12, and the single-core ferrule 9) is simplified, and the work of assembling and adjusting each component is also simplified. Therefore, according to the present invention, a compact and high-performance optical circuit module can be mass-produced at low cost.

FIG. 5 shows a second embodiment of the present invention. In the present embodiment, unlike the first embodiment shown in FIG. 3, the wedge glass plate 23 for bending the optical path is used.
A dielectric multilayer film as the optical multiplexing / demultiplexing filter 22 is formed on the surface of the optical multiplexing / demultiplexing filter 22.

As a result, in the first embodiment, the optical multiplexing / demultiplexing filter 22 and the wedge glass plate 23, which are formed of separate members, are integrated and shared, thereby reducing the number of parts. Can be reduced. Further, since the adjustment of the positional relationship between the components is not required for one set, the adjustment is facilitated. Therefore, this embodiment contributes to further downsizing of the module and improvement of assemblability. Note that the other configuration and operation and effect are the same as those of the above-described first embodiment, and a detailed description thereof will be omitted.

FIG. 6 shows a third embodiment of the present invention. As compared with the first embodiment shown in FIG. 3, the front and back sides of the wedge glass plate 23 are opposite.
Even in this manner, the same operation and effect as in the first embodiment can be obtained. In this embodiment, as in the second embodiment, the optical multiplexing / demultiplexing filter 22 and the wedge glass plate 23 may be used in common.

FIG. 7 shows a fourth embodiment of the present invention. As compared with the third embodiment shown in FIG. 6, the arrangement order of the optical multiplexing / demultiplexing filter 22 and the wedge glass plate 23 is different. As described above, the optical arrangement relationship can be appropriately set according to the characteristics and form of each component to achieve the intended optical path, but the specific configuration is not uniform.

FIG. 8 shows a fifth embodiment of the present invention. This embodiment is based on the configuration of the third embodiment shown in FIG. 6, and has an optical isolator 24 disposed between the wedge glass plate 23 and the collimating lens 12. As a result, the optical multiplexer / demultiplexer is provided with an optical isolator function, thereby increasing the added value. As described above, it is possible to freely add an optical component or an optical element having a necessary function to the module according to the specific purpose of use.

In each of the above-described embodiments, the shape of the wedge glass plate is a single trapezoidal shape. However, the present invention is not limited to this, and the shape may be any if the optical path is appropriately bent. Does not matter. For example, the shape may be triangular as shown in FIG. In this case, assuming that the apex angle of the wedge glass plate 23 'is (A + B), sin (θ + B) = n · sin (A + B−sin)
^-1 (sinA / n)) may be set for each angle.

[0037]

As described above in detail, in the optical circuit module of the present invention, the two-core ferrule, the first collimating lens, the optical multiplexing / demultiplexing filter, the wedge glass plate, the second collimating lens, and the one-core ferrule. Are arranged in almost the same straight line, and in this arrangement relation, the whole is housed in one cylindrical case. Then, two optical fibers are drawn out in parallel from one end of the cylindrical case, and one optical fiber is drawn out from the other end of the cylindrical case.

With such a module configuration, the outer shape of the case becomes a simple cylindrical shape as compared with the module configuration of the conventional configuration, and the outer size can be significantly reduced compared with the conventional configuration. Further, the arrangement of the three optical fibers at the time of mounting is simple, and the mounting space can be extremely reduced.
Further, since the two optical fiber core wires included in the two-core ferrule are very close, the two core wires can be handled by a common collimating lens. This also contributes to downsizing of the module case.

Moreover, by providing the wedge plate,
Since both ferrules can be arranged in the same straight line or in parallel, the angle can be easily adjusted when the ferrule is assembled to the case.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a backward pumping type optical fiber amplifier as an example of an application object of the present invention.

FIG. 2 is a schematic diagram showing a conventional configuration example of an optical multiplexing / demultiplexing circuit module in the optical fiber amplifier.

FIG. 3 is a schematic configuration diagram of an optical multiplexing / demultiplexing circuit module according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a wedge glass plate.

FIG. 5 is a schematic configuration diagram of an optical multiplexing / demultiplexing circuit module according to a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of an optical multiplexing / demultiplexing circuit module according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an optical multiplexing / demultiplexing circuit module according to a fourth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an optical multiplexing / demultiplexing circuit module according to a fifth embodiment of the present invention.

FIG. 9 is a view showing another form of the wedge glass plate.

[Explanation of symbols]

 Reference Signs List 1 optical isolator 2 erbium-doped optical fiber 2a optical fiber core 3 optical multiplexing / demultiplexing circuit 4 optical fiber 4a optical fiber core 5 optical isolator 6 excitation light source 7 optical fiber 7a optical fiber core 8, 9, 10 1-core ferrule (conventional) 11 , 12, 13 Collimating lens (conventional) 14 Optical multiplexing / demultiplexing filter (conventional) 20 2-core ferrule 21 Collimating lens 22 Optical multiplexing / demultiplexing filter 23 Wedge glass plate (Wedge plate) 24 Optical isolator Ms Module main shaft

Claims (2)

[Claims] 1. A two-core ferrule (20) having a core wire (2a, 7a) of two parallel optical fibers (2, 7);
A single-core ferrule (9) having a core (4a) of one optical fiber (4) is disposed substantially coaxially on a single linear module main shaft (Ms), and the tip surfaces of the two ferrules Are opposed at a predetermined interval, and a first collimating lens (21) facing the distal end surface of the two-core ferrule (20), and a second collimating lens (21) facing the distal end surface of the single-core ferrule (9). Collimating lens (1
2) and an optical multiplexing / demultiplexing filter (22) and a wedge plate (23) interposed between the first and second collimating lenses, the module main shaft (Ms) at a space between the tip surfaces of the two ferrules. ) Are arranged side by side in series, and the vertex angle of the wedge plate is
The core wire (4a) of the one-core ferrule (9) in a state where the axes of the core ferrule and the first and second collimating lenses are arranged parallel or linear to the module main axis (Ms).
And one of the core wires (2a) of the two-core ferrule (20) are optically coupled in a transmission optical path of the optical multiplexing / demultiplexing filter (22), and the two core wires (2a, 2a) of the two-core ferrule (20) are connected.
An optical circuit module, wherein 7a) is optically coupled in a reflection optical path of the optical multiplexing / demultiplexing filter (22). 2. The optical circuit module according to claim 1, wherein a dielectric multilayer film as said optical multiplexing / demultiplexing filter (22) is formed on a surface of said wedge plate (23).