JPH08248275A - Optical circuit module for optical amplifier - Google Patents

Abstract

PURPOSE: To provide an optical circuit module for optical amplifier reducing a coupling loss. CONSTITUTION: In an optical circuit module for optical amplifier utilized by attaching to an optical amplifier for amplifying a signal light beam transmitted from an EDF 1 by introducing exciting light to the EDF (erbium doped optical fiber), this module is provided at least a pair of signal light collimators 22, 24 arranged on both end surfaces of the optical circuit module and inputting/ outputting signal light, comprises a first optical path for optically coupling signal light beams having specified wavelengths with parallel beams as the beam shapes mutually in coincident through a LWPF 26 and an isolator 29 between the pair of signal light collimators 22, 24 and a second optical path for optically coupling another exciting light having a specified wavelength with parallel beams as the bean shapes mutually in coincident between the signal light collimator 22 in the pair of the signal light collimators and a LD collimator 34 of the exciting light and an aspherical lens for LD collimator 33 and a semiconductor laser element 32 for transmitting the exciting light are arranged on the second optical path in the optical circuit module by a prescribed interval (d).

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 attached to an optical amplifier, and more particularly to an optical circuit module for an optical amplifier attached to an optical amplifier having an optical fiber amplifier made of a rare earth element-doped optical fiber. . The optical amplifier according to the present invention directly amplifies light by utilizing the non-linearity of the optical fiber. Particularly, among the above-mentioned rare earth element-doped optical fibers, an erbium-doped optical fiber (hereinafter referred to as EDF) is used. The optical amplifier used is currently in practical use.

[0002]

2. Description of the Related Art FIG. 9 is an explanatory diagram showing a basic configuration of a conventional optical amplifier, and FIG. 10 is a schematic explanatory diagram of an optical circuit module in which a portion A shown by a dotted line in FIG. 9 is integrated. In FIG. 9, 1 is an EDF, 2 is a signal light input connector, 3
Is an isolator, 4 is a semiconductor laser module of an excitation light source, and 5 is a 1.55 μm reflecting a 1.48 μm band excitation light.
LWPF (common name for long wave pass filter) that passes band signal light, 6 is an isolator, 7 and 8 are couplers that branch signal light, 9 is a light receiving element that monitors the signal light, and 10 is a reflected light monitor Is a monitor light output connector, and 12 is a signal light output connector.

First, the operation of the conventional example shown in FIG. 9 will be described. The 1.48 μm band pump light output from the semiconductor laser module 4 used as the pump light source is reflected by the LWPF 5 and input to the EDF 1. On the other hand, the signal light input connector 2
The 1.55 μm band signal light input from the isolators 3
And then input to EDF1, where 1.48 above
Amplified by the μm band excitation light. The amplified signal light passes through the isolator 6 via the LWPF 5, and then is partly branched (for example, 10: 1) by the coupler 7, and most of the signal light passes through the coupler 7 and is output from the signal light output connector 12. To be done. On the other hand, the signal light reflected by the coupler 7 is the coupler 8
After passing through, the light is input to the light receiving element 9 and is electrically converted. This electric signal is output as a monitor output, and the change in this output is constantly monitored and fed back to the output of the pumping light source to be used for the function of automatic level control (ALC) so as to keep the signal output constant. Then, the signal light branched by the coupler 8 is output from the monitor light output connector 11 as monitor light. An optical amplifier that amplifies based on the above-described operation principle is called a backward pumping type.

Here, it is assumed that the optical connector or the like is disconnected. In this case, since high-power laser light is sent to the transmission line, it may adversely affect people around. When such a trouble occurs, the following functions work as a method of preventing it. For example, when the signal light output connector 12 is disconnected,
The end face has a boundary between the fiber and the air, and since the refractive index of the fiber and the refractive index of the air are significantly different from each other before the deviation, the reflected light returns with a return loss of about −14 dB. The reflected light is partially reflected by the coupler 7 and input to the light receiving element 10 to be electrically converted. When this electrical level is monitored and a certain level of light is input, it is determined that the signal light output connector 12 is disconnected, and the output of the optical amplifier is lowered. For example, the driving of the semiconductor laser module 4 is stopped. As another accident prevention measure, for example, there is a configuration in which the isolator 6 allows light to pass in the direction of the arrow but does not allow light to pass in the opposite direction. This serves to prevent oscillation caused by reflection of optical components in the optical amplifier.

At present, in order to miniaturize the optical amplifier, as shown in FIG. 10, an optical circuit module integrating the optical function of the portion A of FIG. 9 is used. In FIG. 10, reference numeral 21 is a case body of the optical circuit module, and reference numerals 22, 23, 24 and 25 are collimators that form parallel beams by using optical fibers and lenses (not shown). That is, 22 is a signal light input collimator, 23 is an excitation light input collimator, 24 is a signal light output collimator, and 25 is a monitor light output collimator. Reference numeral 26 is a dielectric multilayer film, which is 1.48 μm of excitation light.
LWPFs 27, 28 that reflect the m-band pumping light and pass the 1.55 μm-band signal light are couplers that branch the light in order to monitor the signal light. Reference numeral 29 is an isolator, 30 is a light receiving element for signal light monitoring, and 31 is a light receiving element for monitoring for monitoring reflected light. The optical circuit module of FIG. 10 is basically the same as the configuration of FIG. 9 except that the part number is changed and the signal light input collimator 22 and the excitation light input collimator are attached to the case body, and therefore the function is the same. The description is omitted.

[0006]

However, in the conventional optical circuit module for optical amplifier as described above, the semiconductor laser module used as the pumping light source is mounted as a separate device, and therefore the pumping light input collimator is used. Optical circuit module.
Therefore, the total loss of the pumping light system is 2.2 dB in the structure of the semiconductor laser module of the pumping light source, the opposing loss of 0.5 dB between the signal light input collimator and the pumping light input collimator in the optical circuit module, and the pumping light source's loss. There was a problem that the fusion splicing loss of 0.1 dB between the fiber end of the semiconductor laser module and the fiber end of the pumping light input collimator was added, resulting in a loss of 2.8 dB (coupling efficiency 43%).

[0007]

An optical circuit module for an optical amplifier according to the present invention amplifies signal light emitted from a rare earth element-doped optical fiber by introducing pumping light into the rare earth element-doped optical fiber. An optical amplifier optical circuit module used by being attached to an optical amplifier for outputting amplified signal light, comprising at least a pair of signal light collimators arranged on both end faces of the optical circuit module for inputting and outputting the signal light. A first optical path optically coupled by a parallel beam having a beam shape in which signal lights of a specific wavelength are mutually matched via an LWPF and an isolator between optical collimators, and pumping light of another specific wavelength different from the specific wavelength Is a beam shape in which one of the pair of signal light collimators described above and the LD collimator of the excitation light are mutually matched through the LWPF. Second optically coupled with some parallel beam
And an aspherical lens for an LD collimator and a semiconductor laser element for emitting excitation light are arranged on the second optical path in the optical circuit module at a predetermined interval.

Here, in this optical circuit module for optical amplifier, the other specific wavelength of the pumping light is 1.48 μm,
When the specific wavelength of the signal light is 1.55 μm, it is suitable to be applied to EDF as a rare earth element-doped optical fiber used for an optical amplifier. In each of the pair of signal light collimators provided in the first optical path, the optical coupling loss is minimized by adjusting the distance between the single mode fiber (EDF) forming the collimator and the aspherical lens. And the one of the signal light collimators by adjusting the distance between the aspherical lens of the aspherical lens for LD collimator arranged on the second optical path and the semiconductor laser element. It is arranged so that the coupling efficiency is maximized. Further, in this case, the semiconductor laser element, the aspherical lens for the LD collimator of the pumping light, and one of the signal light collimators are arranged so that the coupling efficiency thereof is maximized at the other specific wavelength described above. It is necessary that the beam shape is obtained by the optical adjustment of the optical power so that it substantially matches the beam shape of the signal light collimator.

Further, as an optical circuit module for an optical amplifier formed by another structure, an LWP arranged on the optical path (corresponding to the first optical path) of the signal light of this optical circuit module.
An optical path of the excitation light, which is composed of F, an excitation semiconductor laser element that emits the excitation light reflected by the LWPF and introduced into the rare-earth element-doped optical fiber, and an aspherical lens for the LD collimator of the excitation light (the second optical path). (Corresponding to) and) may be internally provided. Here, another optical component may be added to the optical circuit module for the simplified optical amplifier described above, and an isolator may be provided outside the LWPF arranged on the optical path of the signal light of the optical circuit module. Good.

[0010]

According to the present invention, first, an aspherical lens for an LD collimator, which is an optical component for pumping light of a specific wavelength different from the specific wavelength of signal light, and a semiconductor laser element for pumping are built in an optical circuit module. Due to the characteristics of the aspherical lens for the LD collimator, it is possible to optically couple the excitation light to one signal light collimator of the pair of signal light collimators by a parallel beam having a beam shape that substantially matches each other. Since the output power of the pumping semiconductor laser device can be coupled into the EDF with high coupling efficiency, an optical path of pumping light with low coupling loss is formed.

According to another aspect of the invention, an optical circuit module is provided with at least an LWPF on an optical path of a signal light and a pumping semiconductor laser for emitting pumping light reflected by the LWPF and introduced into a rare earth element-doped optical fiber. In the case where the element and the optical path of the excitation light including the aspherical lens for the LD collimator of the excitation light are provided internally,
The configuration is applicable to both the forward-pumped and backward-pumped optical amplifiers. Further, an optical circuit module formed by adding an isolator to the optical path of signal light in the configuration of the optical circuit module described above is also applicable to both the forward pumping type and backward pumping type optical amplifiers. Then, a configuration in which a monitor coupler, a light receiving element, and a signal input connector are added to the configurations of these other inventions can be applied as, for example, an optical amplifier dedicated to the forward pumping type.

[0012]

【Example】

[First Embodiment] FIG. 1 is a schematic diagram showing an embodiment of an optical circuit module for an optical amplifier according to the present invention. As is apparent from the figure, the optical circuit module has a configuration in which a semiconductor laser element for emitting excitation light and an optical system for excitation light collimation are incorporated. In the configuration of FIG. 1, first, in the optical system of the present optical circuit module, 1.5
In order to minimize the loss of the signal light of 5 μm band, the signal light input collimator 22 and the signal light output collimator 24 are set to the collimator facing optimally adjusted at a predetermined facing distance L1 + L2. The optimum adjustment just described is adjusting the facing distance between the single mode fiber and the lens forming the collimator so that the coupling loss of the optical power is minimized at a specific signal light wavelength. In addition,
The adjusted light path according to this configuration is referred to as a first optical path in the present optical circuit module.

FIG. 8 is an explanatory view showing the first optical path, that is, the collimator facing of the signal light, in which the light emitted from the single mode fiber 1a is converted into a collimated beam (parallel beam) by the aspherical lens 41 and facing. Distance L1 + L
After passing through 2, the single mode fiber 1b is coupled by the aspherical lens 42. In this case, the single mode fiber 1b and the aspherical lens 42 also make a beam traveling in the opposite direction into a collimated beam (parallel beam) for optical coupling. However, this configuration is similar in the case of the conventional example of FIG. The specific structure for achieving the opposition to the signal light collimator is as follows. F2.5 aspherical lenses are used as the aspherical lenses 41 and 42, and single-mode fibers 1a and 1b obliquely polished by 8 degrees are used, and the facing distance L1 +
As a result of optimal adjustment with L2 = 50 mm, the opposing loss is 0.
The optimum configuration was obtained at 2 dB. Here, the LWPF 26 that reflects the excitation light is fixed at a position of a predetermined distance L1. However, this configuration is similar in the case of the conventional example of FIG.

On the other hand, in the present embodiment, in order to solve the problem of the conventional apparatus such as the loss of the excitation system as described above, the semiconductor laser element of the excitation light source and the aspherical lens for the LD collimator are installed in the case body 21. It is supposed to do.
Therefore, the 1.48 μm band pumping light of another specific wavelength converts the outgoing beam of the pumping semiconductor laser element 32 into a collimated beam by the LD collimator aspherical lens 33 and couples it to the signal light input collimator 22 at the coupling distance L1 + L3. Adopted a configuration to allow. Here, the excitation semiconductor laser device 3
The distance between 2 and the end surface of the LD collimator aspherical lens 33 on the LD side is d, and the distance between the end surface of the LD collimator aspherical lens 33 on the collimated beam exit side and the LWPF 26 is L3. The LD collimator aspherical lens 33 has an f0.75 aspherical lens, and the 1.48 μm band excitation semiconductor laser element 32 has an FFP (Far-Field).
d Pattern: far field image) 24 ° (1 / e ² , half angle) was used.

The coupling efficiency between the signal light input collimator 22 and the pumping LD collimator 34 shown in FIG. 1 is the coupling distance L1 +.
It has a binding property with high coupling efficiency such that L3 is 68% or more in the range of 20 to 70 mm. That is, in this configuration, a highly efficient coupling characteristic is obtained without largely depending on the facing distance between the facing collimators, for example, the axial deviation distance between the signal light input collimator 22 and the pumping LD collimator 34 in the optical axis direction. There is. The coupling condition of the second optical path with which such a configuration is obtained will be described below with reference to FIG.

As shown in FIG. 2, the beam shape of the coupling system when a high coupling characteristic is obtained is a coupling system of collimators with no coupling loss, and the collimated beam shapes of the collimators are the same. It is that. That is, as shown in FIG. 2, the LD formed by the collimated beam shape (a) of the 1.48 μm pumping light emitted from the signal light input collimator 22, the pumping semiconductor laser element 32, and the LD collimator aspherical lens 33. When the shapes (b) of the collimated beams match each other, the coupling efficiency becomes 100%. Therefore, in order to obtain high coupling efficiency, the shape (b) of the LD collimated beam may be matched with the shape (a) of the collimated beam from the signal light input collimator 22. In this case, the shape (b) of the LD collimated beam is determined by the LD collimator aspherical lens 33, but also depends on the change in the distance d. Therefore, by adjusting d, high efficiency coupling is set.

FIG. 3 shows another comparative example (FIGS. 4, 5 and 6).
FIG. 3 is an explanatory diagram in which FIG. 2 is rewritten for easy comparison with FIG. 2. In each of these figures, a thick solid line indicates the collimated beam shape (a) from the signal light input collimator 22 (the traveling direction of the collimated beam). Of the light intensity distributed in the plane perpendicular to the
(e ² ) is plotted with respect to the traveling direction of the beam), and the thick dotted line indicates the shape (b) of the LD collimated beam. As in the case of FIG. 3, a combination of beam shapes as shown in the comparative examples of FIGS. 4, 5 and 6 can obtain high coupling efficiency in addition to the case of combining in a nearly perfect parallel beam shape. it can. The reason is that, in any case, the beam of the solid line and the beam of the dotted line coincide with each other. However, since it is not a parallel beam shape as shown in FIG. 3, the coupling efficiency changes greatly due to the axial deviation of the collimator between the collimator facings, and the shape depends largely on the facing distance. Therefore, based on the comparison result between the above three comparative examples and this embodiment, the present optical coupling system has the parallel beam shape shown in FIG. 3 and the optimum coupling can be achieved by adjusting the distance d. A signal light collimator facing and an LD collimator are configured and used in this embodiment.

In the above description of FIG. 3, "combining in a substantially perfect parallel beam shape" is because it is not a perfect parallel beam in a strict sense.
The reason for this is that the collimator parallel beam does not always have a constriction called a beam waist that narrows the light intensity distribution, and is not perfectly parallel (the light intensity is expressed as a Gaussian beam). By being done.) However, by making this constriction as small as possible, it becomes possible to make it close to a parallel beam, and it can be said that it is a nearly perfect parallel beam shape.

The operation will be described below. 1.48μ
The excitation light emitted from the m-band excitation semiconductor laser element 32 is converted into a collimated beam by the LD collimator aspherical lens 33, reflected by the LWPF 26, coupled to the signal light input collimator 22, and input to the EDF 1. on the other hand,
The 1.55 μm band signal light input from the signal light input connector 2 passes through the isolator 3, is input to the EDF 1, and is amplified by the input of the pump light described here. The amplified signal light becomes a collimated beam at the signal light input collimator 22, passes through the LWPF 26 and the isolator 29, and then is partially branched (for example, 10: 1) by the coupler 27, and most of the signal light passes through the coupler 27. Then, it is coupled to the signal light output connector 24 and output from the signal light output connector 12. On the other hand, the signal light reflected by the coupler 27 passes through the coupler 28 and receives the signal light monitoring light receiving element 30.
Input to and converted to electricity. This electric signal is output as a monitor output, and the change in this output is constantly monitored and fed back to the output of the pumping light source to be used for the function of automatic level control (ALC) so as to keep the signal output constant. The signal light branched by the coupler 28 is output from the monitor light output connector 11 as monitor light.

Here, if the optical connector or the like is disconnected, high-power laser light is sent to the transmission path, which may adversely affect the human body. As a method of preventing such a trouble, the following functions have come to work. For example, when the signal light output connector 12 is disconnected,
The end surface has a relationship in which the fiber and the air are bound to each other, and since the refractive index of the fiber and the refractive index of the air are different, the reflected light returns with a return loss of about −14 dB. The reflected light is partially reflected by the coupler 27 and input to the light receiving element 31 to be electrically converted. When this level is monitored and a certain level of light is input, it is determined that the signal light output connector 12 is disconnected, and the output of the optical amplifier is lowered. For example, the driving of the semiconductor laser module 4 is stopped. As another accident prevention measure, for example, there is a configuration in which the isolator 29 allows light to pass in the direction of the arrow but does not allow light to pass in the opposite direction. This serves to prevent oscillation caused by reflection of optical components in the optical amplifier. The optical amplifier according to the operation / action as in this embodiment is the same as that described in the conventional example, and is of the backward pumping type.

As described in detail above, in the optical system of the optical circuit module of the first embodiment, for example, when the opposing distance L1 + L3 of the pumping optical system is L = 70 mm, the output power of the pumping semiconductor laser device is reduced to the coupling loss 1. 25 dB (coupling efficiency 7
It is possible to bind to EDF at 5%). This is an improvement of about 1.5 dB from the total loss of 2.8 dB when mounted as a conventional individual device as shown in the conventional example of FIG. 9, and the optical system according to the present invention is sufficiently effective. It shows the effect that low loss can be achieved. Furthermore, if 100 mW is required as the pumping light input to the EDF, 100 mW is required to realize it.
This was achieved by modularizing the output semiconductor laser device and combining two polarized waves in the optical circuit module. From the results of the first embodiment, 130 mW (100
A single semiconductor laser device with an output of mW / 0.75) can be used. Therefore, it is possible to obtain the effects of downsizing the entire device, reducing loss, and reducing power consumption.

[Second Embodiment] FIG. 7 is a schematic explanatory view showing another embodiment of the present invention. In the present embodiment, the module of the embodiment shown in FIG. 1 is of the backward pumping type, but constitutes an example of the forward pumping type optical amplifier. Further, this embodiment uses the same components as those of the embodiment of FIG. 1, but has a configuration in which their optical arrangements are slightly changed. That is, the optical circuit module for an optical amplifier in this case is one in which the components shown in the broken line frame in FIG. 7 are built in to form the optical circuit module. First, an LWPF (also referred to as WDM) 26 as an excitation optical component, an excitation semiconductor laser element 32, an aspherical lens 33 for an LD collimator, an isolator 3 used in the rear, and a monitor for an input signal optical component. The coupler 28, the signal light monitoring light receiving element 30 and the signal light input connector are built in to form an optical circuit module of a forward pumping type optical amplifier.

Although detailed description is omitted to avoid duplication, in this configuration, the EDF 1 is arranged in front of the above-mentioned pumping system optical component (signal light output side), and the LWPF 2 is attached to this EDF 1.
By inputting the pumping light reflected by 6, the forward pumping type optical amplification is performed. Then, the amplified signal light is directly output from the signal light output connector 12.

[Third Embodiment] In this embodiment, the components within the thick dotted line frame of FIG. 7 are configured as an optical circuit module of an optical amplifier in the arrangement shown in the drawing. That is, the LWPF 26 as the pumping optical component, the pumping semiconductor laser element 32, the aspherical lens 33 for the LD collimator, and the isolator 3 for controlling the direction of the signal light are incorporated in one case body to provide an optical circuit for an optical amplifier. It is a module. This configuration is characterized in that it is possible to provide an optical circuit module that can be used for both the forward pumping type and the backward pumping type, depending on the orientations of the LWPF 26 and the isolator 3.

[Fourth Embodiment] In this embodiment, the components within the thick solid line frame in FIG. 7 are configured as an optical circuit module of an optical amplifier in the arrangement shown in the drawing. That is, the optical circuit module for the optical amplifier is formed by incorporating only the LWPF 26 as the excitation system optical component, the excitation semiconductor laser element 32, and the aspherical lens 33 for the LD collimator. This configuration provides an optical circuit module that can be used for both the forward pumping type and the backward pumping type.

As described in detail above, according to the optical system of the optical circuit module of the second embodiment, some main parts of the same components as those of the embodiment of FIG. 1 are used, and their optical arrangement is slightly changed. Since the optical circuit module is formed by incorporating the components shown in the wavy frame in FIG. 7 into a different configuration, the optical circuit module of the forward pumping type optical amplifier can be formed relatively easily. is there. Further, according to the optical systems of the optical circuit modules of the third and fourth embodiments, among the components used in the embodiment of FIG. 1, only the LWPF, the pumping semiconductor laser element and the aspherical lens for the LD collimator, or Since an optical circuit module is formed by using an isolator in addition to these components, both have the effect that an optical circuit module that can support both forward-pumped and backward-pumped optical amplifiers can be provided. To be

[0027]

As described in detail above, according to the present invention, in particular, a pumping semiconductor laser element and an aspherical lens for LD collimator that constitute a pumping light optical system are incorporated in an optical circuit module by a predetermined optical arrangement. As a result, the output power of the pumping semiconductor laser device is reduced to a coupling loss of 1.25 dB.
The effect that it was possible to bind to EDF with (coupling efficiency of 75%) was obtained. This is an improvement of about 1.5 dB from the total loss of 2.8 dB in the case of the semiconductor laser module mounted as a conventional individual device, and the optical system according to the present invention has a sufficiently low loss. I was able to obtain the achievable effect. Furthermore, E
When 100 mW was requested as an example of pumping light input to the DF, the realization was achieved by modularizing a semiconductor laser device with a 100 mW output and combining two polarizations in an optical circuit module. According to the results of the present invention, one semiconductor laser device having an output of 130 mW can be used, and since the handling of the optical fiber can be eliminated, the overall size of the device can be reduced, the loss can be reduced, and the power consumption can be reduced. The effect that it can be achieved is obtained. Further, by constructing a simplified optical circuit module in which the components to be arranged in the optical circuit module are limited to a small number of main components such as an optical system for pumping light and at most one isolator, forward pumping Type or backward pumping type optical amplifier.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical circuit module for an optical amplifier according to the present invention.

FIG. 2 is a schematic diagram for explaining a coupled state of the excitation light optical system of the present invention.

FIG. 3 is an explanatory diagram of FIG. 2 in which a beam shape of another comparative example is rewritten for easy comparison.

FIG. 4 is an explanatory diagram of a comparative example for comparison with the coupled state of the pumping light optical system of the present invention.

FIG. 5 is an explanatory diagram of another comparative example for comparison with the coupled state of the excitation light optical system of the present invention.

FIG. 6 is an explanatory diagram of another comparative example for comparison with the coupled state of the excitation light optical system of the present invention.

FIG. 7 is a schematic explanatory view showing another embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a signal light of the present invention facing a collimator.

FIG. 9 is an explanatory diagram showing a basic configuration of a conventional optical amplifier.

FIG. 10 is a schematic explanatory diagram of an optical circuit module in which the portion A shown by the dotted line in FIG. 9 is integrated.

[Explanation of symbols]

 1 Erbium Doped Optical Fiber (EDF) 1a, 1b Single Mode Fiber 2,22 Signal Optical Input Connector 3,6,29 Isolator 4 Semiconductor Laser Module 5,26 LWPF (Long Wave Pass Filter) 7,8,27,28 Coupler 9 , 10 light receiving element 11 monitor output connector 12 signal light output connector 21 case body 23 excitation light input collimator 24 signal light output collimator 25 monitor output collimator 30 signal light monitoring light receiving element 31 monitor light receiving element 32 excitation semiconductor laser element 33 LD Aspherical lens for collimator 34 LD collimator for excitation 41, 42 Aspherical lens

Claims (6)

[Claims] 1. Light used by being attached to an optical amplifier for amplifying signal light emitted from the rare earth element-doped optical fiber by introducing pumping light into the rare earth element-doped optical fiber and outputting the amplified signal light. In an optical circuit module for an amplifier, the optical circuit module is provided with at least a pair of signal light collimators which are arranged on both end surfaces and through which the signal light is input and output,
A first optical path that optically couples a pair of signal light collimators through a long wave pass filter and an isolator with parallel beams having a beam shape in which the signal lights having a specific wavelength match each other, and the specific wavelength. Between the signal light collimator of the pair of signal light collimators and the aspherical lens for LD collimator of the pump light through the long wave pass filter. A second optical path for optically coupling with a parallel beam having a beam shape corresponding to the aspherical lens for LD collimator and a semiconductor laser element for emitting the excitation light, the second optical path in the optical circuit module. An optical circuit module for an optical amplifier, characterized in that an LD collimator for excitation is formed by arranging the LD collimator at a predetermined interval on the optical path 2. 2. The rare earth element-doped optical fiber is an erbium-doped optical fiber, the other specific wavelength of the pumping light is 1.48 μm, and the specific wavelength of the signal light is 1.48 μm.
The optical circuit module for an optical amplifier according to claim 1, wherein the optical circuit module has a thickness of 55 μm. 3. The optical coupling loss is minimized by adjusting the distance between the single mode fiber and the aspherical lens that constitute the collimator in each of the pair of signal light collimators provided in the first optical path. The LD collimator aspherical surface is further arranged on the second optical path after the first optical path is arranged so that the coupling loss of the first optical path is minimized. By adjusting the distance between the aspherical lens of the lens and the semiconductor laser element, it is arranged so that the coupling efficiency with any one of the signal light collimators is maximized, and an LD collimator for excitation is configured. The optical circuit module for an optical amplifier according to claim 1, wherein 4. The semiconductor laser device, the aspherical lens for LD collimator of the pumping light, and one of the signal light collimators are arranged so that the coupling efficiency thereof becomes maximum at the another specific wavelength. 4. An optical circuit for an optical amplifier according to claim 3, wherein a pumping LD collimator is configured, and the beam shape of the pumping LD collimator is obtained by optical adjustment that substantially matches the beam shape of the signal light collimator. module. 5. An optical amplifier attached to an optical amplifier for amplifying signal light input to said rare earth element-doped optical fiber by introducing pumping light into said rare earth element-doped optical fiber and outputting the amplified light. In the optical circuit module for use, a long wave pass filter disposed on the optical path of the signal light of the optical circuit module and pumping light reflected by the long wave pass filter and introduced into the rare earth element-doped optical fiber are emitted. An optical circuit module for an optical amplifier, wherein a pumping semiconductor laser element and a lens for an LD collimator for pumping light are provided inside. 6. The optical circuit module for an optical amplifier according to claim 5, wherein an isolator is provided outside the long wave pass filter arranged on the optical path of the signal light of the optical circuit module.