JP3062400B2 - Optical circuit module constituting fiber optical amplifier - Google Patents

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 constituting a fiber optical amplifier.

[0002]

2. Description of the Related Art An erbium-doped fiber (hereinafter, sometimes referred to as EDF) optical amplifier has been known as a fiber optical amplifier (for example, a document: "Optical Amplifiers and Their Applications", published by Ohmsha, 1992). Year, 100th
Pp.-111). This EDF optical amplifier includes a backward pumping type and a forward pumping type.

Recently, in order to reduce the size of the EDF optical amplifier, a long wave pass filter (L
An optical circuit module that integrates the optical functions of a portion composed of a WPF, an isolator, and a coupler is used. An example of this is disclosed in the document "Preliminary Proceedings of the 1992 IEICE Autumn Conference, C-222" (p. 4-244).

A configuration of a conventional backward-pumped optical circuit module will be briefly described. FIG. 3 is a simplified configuration diagram for explaining the configuration of a conventional optical circuit module. In the conventional optical circuit module 10, the excitation light 12 input from the first collimator 28 is reflected at a right angle by the LWPF 70, and then output from the second collimator 30 to output the EDF.
(Not shown), the first collimator 28,
The LWPF 70 and the second collimator 30 are arranged. The signal light 14 incident from the second collimator 30 travels in a direction opposite to the direction in which the excitation light 12 enters the second collimator 30. The signal light 14 incident from the second collimator 30 is L
After passing through the WPF 70, it passes through the isolator 26. Most of the signal light 14 that has passed through the isolator 26 passes through the coupler 58 and then passes through the third collimator 32
Output from Thus, the LWPF 70, the coupler 5
8. The third collimator 32 is arranged. Also, the coupler 58
As a result, the signal light 14 that is partially reflected enters the monitor light receiving element 66.

When an optical amplifier is constructed using such an optical circuit module 10, it is necessary to process the extra length of the optical fiber for connection between the optical circuit module and the EDF, attachment of an external output connector, and the like. At this time, it is necessary to secure an allowable bending radius of the optical fiber in order to process the extra length of the optical fiber.

[0006]

In the conventional optical circuit module, the optical fibers are provided on three sides of the square case body, and the optical fiber is drawn out in three directions. Spaces for processing the length need to be provided in three directions, which hinders miniaturization of the optical amplifier. In addition, the housing of the optical fiber is poor,
There is a problem that the work efficiency of assembling the optical amplifier is reduced.

Further, since the excitation light and the signal light input to the optical circuit module are reflected once by the filter and then output, the optical element due to the angle shift or the axis shift at the time of fixing the filter or at the time of expansion and contraction due to temperature change. There is also a problem that the coupling loss between them or between the optical element and the optical fiber increases.

[0008] Here, the problems of the conventional backward-pumped optical circuit module have been described, but the same problem exists in the forward-pumped optical circuit module.

Therefore, it has been desired to achieve the following object in an optical circuit module.

That is, an object of the present invention is to provide an optical circuit module for an EDF optical amplifier which can be miniaturized, has excellent workability in assembling, has small coupling loss, and has high reliability. is there.

[0011]

Therefore, according to the optical circuit module of the invention of the present application, pump light is input,
Of the respective functions of outputting pump light, inputting signal light, and outputting signal light, a plurality of ports having any one or more functions, and a block shape of a type that reflects two or more even times The first constructed with the optical element of
A reflection optical system, comprising a first reflection optical system for guiding excitation light from a port having a function of inputting excitation light to a second reflection optical system, and a block-shaped optical element that reflects two or more times evenly. The second reflection optical system,
The first reflection optical system has a function of guiding the excitation light to the port having a function of outputting the excitation light without using refraction, while guiding the excitation light, and a function of outputting the signal light from the port having a function of inputting the signal light. A second reflection optical system that guides the signal light to the port; and an isolator that is provided in the optical path of the second reflection optical system and outputs the signal light to a port that has a function of passing the signal light and outputting the signal light. All the ports are on the same side with respect to the optical circuit module, so that the optical axes of the input and output light of the pump light and the signal light are parallel,
It is characterized by being provided.

According to the optical circuit module of another invention according to the present application, of the functions of inputting pump light, outputting pump light, inputting signal light, and outputting signal light,
A first reflection optical system including a plurality of ports having any one or a plurality of functions and a block-shaped optical element of a type that reflects two or more times, and has a function of inputting excitation light. First reflection optics for guiding the excitation light such that the light enters the port having a function of outputting the excitation light from the port having the function of perpendicularly entering the incident surface of the optical element and emitting the light perpendicularly to the exit surface of the optical element. A second reflection optical system comprising a system and a block-shaped optical element of a type which reflects two or more times, wherein the port has a function of outputting signal light from a port having a function of inputting signal light And a second reflection optical system for guiding the signal light so that the light is perpendicularly incident on the incident surface of the optical element and is emitted perpendicularly to the emission surface of the optical element. An isolator that is provided in the optical path of the system and outputs the signal light to a port that has a function of passing the signal light and outputting the signal light. So that each optical axis of each input / output light of signal light is parallel,
It is characterized by being provided.

In the embodiments of the present invention, preferably, a reflection optical system for guiding the signal light from a port for inputting the signal light to a port for outputting the signal light includes two optical elements, and between the optical elements. It is good to arrange an isolator.

[0014]

According to the invention, the pumping light input port, the signal light input port, the pumping light output port and the signal light output port are provided on the same side of the optical circuit module. The input and output directions of the optical fibers are the same. For this reason, the accommodation space for processing the extra length of the optical fiber is required only on one side of the optical circuit module, and the accommodation property of the optical fiber is improved.

Further, in these inventions, the first and second reflecting optical systems are constituted by a block-shaped optical element of a type which reflects two or more times even number of times, so that an angle shift or an axis shift of the optical element occurs. Even so, the light emitted from these optical elements simply shifts in parallel. The relationship between the amount of displacement of the light beam and the coupling loss has a loose tolerance with respect to the axial displacement of the optical element. Therefore, the angle of each block fixing the collimator and the filter due to expansion and contraction due to a temperature change or the like. Even if displacement or axial displacement occurs, the coupling loss is small because the displacement of the light beam is small.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In these drawings, each component is shown only schematically so that the present invention can be understood.
Therefore, the shapes, dimensions, and arrangements of these components are not limited to the illustrated examples.

FIG. 1 is a schematic configuration diagram for explaining a first embodiment of the configuration of the optical circuit module of the present invention. An amplifier having an optical circuit module configured as in this embodiment is called a backward pump type.

The optical circuit module 10 includes an excitation light 12
Is input, the pumping light 12 is output, the signal light 14 is input,
And a plurality of ports having one or more of the functions of outputting the signal light 14, that is, a first port 16, a second port 18, and a third port 20. In this embodiment, the first port 16 has a function of inputting the pumping light 12, the second port 18 has a function of outputting the pumping light 12 and inputting the signal light 14, and the third port 20 has a function of inputting the signal light 14. 14 is provided. The module 10 further includes a first reflection optical system 22 for guiding the pump light 12 from a first port 16 having a function of inputting the pump light 12 to a second port 18 having a function of outputting the pump light 12, and a signal light. A second reflection optical system for guiding the signal light to a third port having a function of outputting the signal light from a second port having a function of inputting the signal light; and a second reflection optical system provided on an optical path of the second reflection optical system. The third port 2 having a function of passing the signal light 14 and outputting the signal light 14
And an isolator 26 for outputting the signal light 14 to zero. In this embodiment, collimators 28, 30 and 32 are provided as respective ports. The collimators 28, 30 and 32 are arranged on one side of the case main body 34, that is, on the same side at a suitable interval according to the design so that their optical axes are parallel.
Here, a second collimator 30 is provided on the left side of the first collimator 28, and a third collimator 32 is provided on the right side.
Is provided. Further, the first reflecting optical system 22 is constituted by block-shaped optical elements 36, and the second reflecting optical system 24 is constituted by block-shaped optical elements 38 and 40. In addition,
Hereinafter, the optical elements 36, 38, and 40 may be simply referred to as blocks. Also, these blocks 36, 38,
40 is made of a suitable transparent optical material, for example, glass or plastic having a low transmittance for signal light or excitation light. Alternatively, the optical element may be fixed by making a hole in metal or the like. And in this embodiment, block 3
An isolator 26 is provided in the optical path between 8 and 40. If necessary, another block-shaped optical element 42 is provided in the optical path between the isolator 26 and the block 40. This optical element 42 may be simply referred to as a block.

The first collimator 28 passes through an optical fiber 44.
1.48 μm input to the optical circuit module 10 from
After the band excitation light 12 is reflected by the reflection mirror 50 formed on one surface of the block 36, it is reflected by the reflection mirror 52 formed on the other surface of the same block 36. The excitation light 12 reflected by the reflection mirror 52 passes through a short wave pass filter (hereinafter, sometimes referred to as SWPF) 54 formed on one surface of the block 38,
The signal is output from the second collimator 30 and input to an EDF (not shown) via the optical fiber 46. The SWPF 54 allows the band of 1.48 μm as the excitation light to pass, but reflects the band of 1.55 μm as the signal light.

The signal light 14 in the wavelength band of 1.55 μm is EDF
(Not shown), the signal light 14 is amplified by the EDF. In this case, the signal light 14 is such that the pump light 12 is E
An input is made to the EDF from a direction opposite to the direction of input to the DF. The amplified signal light 14 travels in a direction opposite to the direction in which the pumping light 12 enters the EDF via the common optical fiber 46, and enters the optical circuit module 10 from the second collimator 30. The signal light 14 input to the optical circuit module 10
Is the SWPF5 formed on one surface of the block 38.
After being reflected at 4, the light is reflected by a reflection mirror 56 formed on the other surface of the same block 38, and travels in a direction perpendicular to the input direction to the optical circuit module 10. Reflection mirror 5
The signal light 14 reflected by 6 passes through the isolator 26. The isolator 26 allows light to pass in one direction and prevents light from passing in the other direction, thereby preventing oscillation caused by reflection of optical components in the optical amplifier. In this embodiment, the isolator 26 allows light to pass in the direction of arrow a. The signal light 14 that has passed through the isolator 26 is partially branched by a coupler 58 formed on one surface of the block 42. By using the coupler 58, the light is branched into, for example, 10: 1. Most of the signal light 14 passing through the coupler 58 is reflected by a reflection mirror 62 formed on one surface of the block 40, and then reflected by a reflection mirror 64 formed on the other surface of the same block 40. Output from the 3 collimator 32. In this way, each of the collimators 28, 30, 32
, Input and output light in the optical circuit module 10 are parallel. On the other hand, the signal light 14 reflected by the coupler 58
Is reflected by a reflection mirror 60 formed on the other surface of the block 42, is input to the monitoring light receiving element 66, is electrically changed, and is output as a monitor output. The reflection mirrors 50, 52, 56, 60, 62, 6 used in this embodiment
4, SWPF 54 and coupler 58 are formed of a dielectric film.

FIG. 2 is a schematic configuration diagram for explaining a second embodiment of the configuration of the optical circuit module of the present invention. An amplifier having an optical circuit module configured as in this embodiment is called a forward pump type.

The configuration of the forward-pumped optical circuit module differs from the backward-pumped optical circuit module described above in the following points. That is, the light passing through the isolator 26 provided in the optical path of the second reflection optical system 24 passes in the opposite direction, and the arrangement direction of the block 42 is different. In the forward pumping type, the signal light 14 is input to the third port 20, that is, the third collimator 32, and is output from the second port 18, that is, the second collimator 30.

Also in this embodiment, the excitation light 12 input to the optical circuit module from the first collimator 28 via the optical fiber 44 passes through the first reflection optical system 22 and then is output from the second collimator 30 to be transmitted to the optical circuit module. E through fiber 46
Input to DF (not shown).

In this embodiment, the signal light 14 enters the optical circuit module 10 from the third collimator 32 via the optical fiber 48. The signal light 14 input to the optical circuit module 10 is reflected by a reflection mirror 64 formed on one surface of the block 40, and then reflected by a reflection mirror 62 formed on the other surface of the same block 40. It proceeds in a direction perpendicular to the input direction to the module 10. The signal light 14 reflected by the reflection mirror 62 is partially branched by a coupler 58 formed on one surface of the block 42. Most of the signal light 14 passing through the coupler 58 passes through the isolator 26. In this embodiment, the isolator 26
Transmits light in the direction of arrow b. The signal light 14 that has passed through the isolator 26 is reflected by a reflection mirror 56 formed on one surface of the block 38,
8 is reflected by the SWPF 54 formed on the other surface of the optical fiber 8, output from the second collimator 30,
Input to DF (not shown). Thus, the optical circuit module 1 for each of the collimators 28, 30, 32
The input and output light within 0 is parallel. Signal light 14 is E
When input to a DF (not shown), the signal light 14 is amplified by the EDF. On the other hand, the signal light 1 reflected by the coupler 58
4 is reflected by a reflection mirror 60 formed on the other surface of the block 42 and then input to the monitoring light-receiving element 66.
The electrical change is made and output as a monitor output.

As can be understood from the first and second embodiments, in the present invention, the first collimator 28
The second collimator 30 and the third collimator 32 are provided on the same side of the optical circuit module so that the optical axes of the input and output lights of the excitation light and the signal light are parallel. Further, inside each block, the signal light or the excitation light is reflected twice.

It is clear that the present invention is not limited to the embodiments described above. For example, in each of the above-described embodiments, the wavelength of 1.48 μm is used as the excitation light. Alternatively, for example, the wavelength of 0.98 μm may be used.

[0027]

As is apparent from the above description, according to the optical circuit module according to each invention of the present application, since the input and output directions of the three optical fibers are the same, the remaining length of the optical fibers is processed. Only needs one space. In addition, the housing of the optical fiber is improved. for that reason,
The size of the optical amplifier can be reduced, and the workability of assembling the optical amplifier can be improved.

Further, the first and second reflecting optical systems are
Since the optical element is constituted by the block-shaped optical element of the type that reflects light even number of times as described above, even if the optical element is misaligned or misaligned, the light emitted from these optical elements is simply shifted in parallel. The relationship between the amount of displacement of the light beam and the coupling loss has a loose tolerance with respect to the axial displacement of the optical element. Therefore, the angle of each block fixing the collimator and the filter due to expansion and contraction due to a temperature change or the like. Even if displacement or axis displacement occurs, the amount of displacement of the light beam is small, so that a highly reliable optical circuit module with little increase in coupling loss can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the configuration of an optical circuit module of the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the configuration of the optical circuit module of the present invention.

FIG. 3 is a schematic configuration diagram for explaining a configuration of a conventional optical circuit module.

[Explanation of symbols]

 10: Optical circuit module 12: Pump light 14: Signal light 16: First port 18: Second port 20: Third port 22: First reflective optical system 24: Second reflective optical system 26: Isolator 28: First collimator 30: second collimator 32: third collimator 34: case body 36, 38, 40, 42: block 44, 46, 48: optical fiber 50, 52, 56, 60, 62, 64: reflection mirror 54: SWPF 58: Coupler 66: Photodetector for monitoring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H04B 10/00 H01S 3/07

Claims (3)

(57) [Claims] An optical circuit module constituting a fiber optical amplifier, wherein one of functions of inputting pumping light, outputting pumping light, inputting signal light, and outputting signal light is provided. Alternatively, a first reflection optical system including a plurality of ports having a plurality of functions and a block-shaped optical element of a type that reflects two or more times, and a second reflection optical system including a port having a function of inputting excitation light and a second reflection optical system. A first reflecting optical system that guides excitation light to the reflecting optical system, and a second reflecting optical system including a block-shaped optical element of a type that reflects two or more times, wherein the first reflecting optical system includes: The pump light is guided to the port having the function of outputting the pump light without passing through the refraction, and the signal is transmitted from the port having the function of inputting the signal light to the port having the function of outputting the signal light. A second reflection optical system that guides the signal light; and an isolator that is provided in the optical path of the second reflection optical system and outputs the signal light to the port that has a function of passing the signal light and outputting the signal light. An optical circuit module, wherein all of the ports are provided on the same side with respect to the optical circuit module so that respective optical axes of the input light and the output light of the excitation light and the signal light are parallel to each other. . 2. An optical circuit module constituting a fiber optical amplifier, wherein one of functions of inputting pump light, outputting pump light, inputting signal light, and outputting signal light is provided. Alternatively, a first reflection optical system including a plurality of ports having a plurality of functions and a block-shaped optical element of a type that reflects two or more times, wherein the port has a function of inputting the excitation light, A first reflection optical system that guides excitation light so as to vertically enter the entrance surface of the optical element and perpendicularly exit the exit surface of the optical element, to a port having a function of outputting The second reflection optical system having a block-shaped optical element of a type that reflects the signal light even number of times, wherein the port has a function of outputting signal light from a port having a function of inputting signal light. A second reflection optical system for guiding the signal light so that the light is perpendicularly incident on the incident surface of the optical element and is emitted perpendicularly to the emission surface of the optical element. An isolator that is provided in an optical path and outputs the signal light to the port having a function of passing the signal light and outputting the signal light; and all the ports are on the same side with respect to the optical circuit module, and the pumping light is provided. And an optical circuit module provided so that optical axes of input and output lights of the signal light are parallel to each other. 3. The optical circuit module constituting the fiber optical amplifier according to claim 1, wherein the second reflection optical system comprises two optical elements, and the isolator is provided between the optical elements. An optical circuit module, which is arranged.