JP2003222769A - Optical module, optical transmitter and wdm optical transmitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module, an optical transmitter and a WDM optical transmitting device for contriving miniaturization of a wavelength monitor, shortness of manufacturing times, improvement of precision of wavelength control and application of an optical filter with a long wavelength cycle without using any beam splitter. <P>SOLUTION: The optical module has an optical transmitting element 1 for outputting a laser beam, the optical filter 3 for transmitting only a laser beam of a prescribed wavelength band output from the light emitting element 1, a wavelength monitoring light receiving element 4 for receiving the laser beam transmitting the optical filter 3, and a power monitoring light receiving element 5 provided between the light emitting element 1 and the optical filter 3 and receiving a part of the laser beam. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of optical communication, and more particularly to wavelength division multiplexing (WDM).
plexing) The present invention relates to an optical module, an optical transmitter, and a WDM optical transmitter used in the field of communication.

[0002]

2. Description of the Related Art Generally, in the field of high density WDM, it is required to precisely control the wavelength of an optical signal and stabilize it for a long period of time. Therefore, an optical transmitter has been developed in which the emission wavelength of the laser light output from the light emitting element is monitored by a wavelength monitor and is fed back to the control of the emission wavelength of the laser light to perform wavelength control at all times.

A conventional optical transmitter having a wavelength adjusting function and a wavelength monitoring function is, for example, Japanese Patent Laid-Open No. 2000-561.
No. 85 publication.

FIG. 8 is an explanatory diagram showing the configurations of a conventional optical module and optical transmitter. As shown in FIG. 8, the conventional optical module is a light emitting element 50 including a semiconductor laser diode or the like that outputs a laser beam having a predetermined emission wavelength, and is optically coupled to the light emitting element 50. (On the right side), an optical fiber 51 for sending the laser light output from the end face to the outside, an optical filter 52 having a cutoff wavelength substantially the same as the emission wavelength of the light emitting element 50, and the rear side of the light emitting element 50 (left side in FIG. 8). ) The laser light output from the end face is
Beam splitter 5 consisting of a half mirror that splits light into two
3, a first light receiving element 54 such as a photodiode which receives one laser beam split by the beam splitter 53 after passing through the optical filter 52, and the other laser beam split by the beam splitter 53 The second light receiving element 55 such as a photodiode and a Peltier module 56 for adjusting the temperature of the light emitting element 50 are provided. A control unit 57 is connected to the optical module. The control unit 57 controls the Peltier module 5 so as to control the wavelength of the light emitting element 50 based on the PD current output from the first light receiving element 54 and the second light receiving element 55.
Control 6

The control unit 57 is, for example, the first light receiving element 5
A first voltage converter 67 for converting the first PD current output from the first light receiving element 4 into a first voltage V1 and a second PD current output from the second light receiving element 55 into a second voltage V2. Controlling the difference or ratio between the second voltage converter 68 for conversion and the first voltage V1 output from the first voltage converter 67 and the second voltage V2 output from the second voltage converter 68. A comparator 69 that outputs as a signal, and a TEC (Thermo) that outputs a temperature control current that raises or lowers the temperature of the Peltier module 56 based on the control signal output from the comparator 69.
Electric Cooler) current generator 70.

Between the light emitting element 50 and the optical fiber 51, a condenser lens 58 for coupling the laser light output from the front end face of the light emitting element 50 to the optical fiber 51 is arranged. Further, a parallel lens 59 is arranged between the light emitting element 50 and the beam splitter 53 to collimate the laser light output from the rear end surface of the light emitting element 50.

The light emitting element 50, the condenser lens 58 and the parallel lens 59 are fixed on the LD carrier 60. The first light receiving element 54 and the second light receiving element 55 are fixed to the first PD carrier 61 and the second PD carrier 62, respectively.

The beam splitter 53, the optical filter 52,
First PD carrier 61 and second PD carrier 62
Are fixed on the metal substrate 63. Metal substrate 63
Are fixed on the surface of the LD carrier 60, and the LD carrier 60 is fixed on the Peltier module 56.

Light emitting element 50, beam splitter 53, optical filter 52, condenser lens 58, parallel lens 59, LD
Carrier 60, first PD carrier 61, second PD carrier 62, metal substrate 63, and Peltier module 56.
Are provided in the package 64. The ferrule 65 that holds the tip of the optical fiber 51 is fixed to the side of the package 64 via a sleeve 66.

The laser light emitted from the front end face of the light emitting element 50 is condensed by the condenser lens 58, is incident on the optical fiber 51 held by the ferrule 65, and is sent to the outside.

On the other hand, the laser light emitted from the rear end face of the light emitting element 50 is made parallel by the parallel lens 59,
Z-axis direction (transmission direction) by beam splitter 53
And an X-axis direction (reflection direction) perpendicular to the Z-axis direction. The laser light branched in the Z-axis direction is
The laser light received by the first light receiving element 54 via the optical filter 52 and branched in the X-axis direction is received by the second light receiving element 55.

First light receiving element 54 and second light receiving element 5
The PD current output from 5 is input to the control unit 57, and the control unit 57 controls the adjusted temperature of the Peltier module 56 so as to control the wavelength of the light emitting element 50 based on the value of the input PD current. To do.

The light output power is monitored by the light receiving element 55 or a separate power monitoring light receiving element, and the light output power is injected into the light emitting element 50 based on a signal output from the light receiving element 55 or a separate power monitoring light receiving element. It is also possible to control the injection current by APC (Auto Power Control).

[0014]

The conventional optical transmitter has the following problems.

(1) A wavelength monitor used in a conventional optical transmitter uses a beam splitter such as a half mirror.
Since the light is split into a plurality of light beams propagating in different directions and the light beams are received by the light receiving elements, respectively, the number of components is increased and the structure of the wavelength monitor is increased. As a result, there is a problem that downsizing of the entire optical module becomes difficult.

(2) In an optical module with a built-in wavelength monitor, it is difficult to accurately arrange a wavelength monitor equipped with a beam splitter in a package, and if it is attempted to arrange it accurately, the manufacturing time of the optical module becomes long. There are challenges.

(3) When the light is split by the beam splitter, the split light is split by utilizing the reflection, transmission and refractive index of the beam splitter, so that the split light is affected by their wavelength dependence and polarization dependence. Particularly in high-density WDM, since highly accurate wavelength control of laser light is required, the wavelength dependence or polarization dependence of the laser light branched into a plurality becomes an error factor of wavelength control.

(4) In a wavelength monitor equipped with a beam splitter, the space for installing an optical filter such as an etalon becomes narrow, so the length of the etalon in the optical axis direction is limited,
There is a problem that the wavelength cycle cannot be lengthened.

The present invention has been made in order to solve the above-mentioned problems, and the wavelength monitor can be miniaturized without using a beam splitter, the manufacturing time can be shortened, the accuracy of wavelength control can be improved, and light with a long wavelength cycle can be used. An object of the present invention is to provide an optical module, an optical transmitter and a WDM optical transmission device to which a filter can be applied.

The present invention also provides an optical module, an optical transmitter, and a WDM optical transmitter which can improve the accuracy of wavelength control by using an optical filter which transmits only laser beams of two different wavelength bands. The purpose is to do.

[0021]

An optical module of the present invention comprises a light emitting element for outputting laser light, an optical filter for transmitting only laser light of a predetermined wavelength band output from the light emitting element, and the optical filter. A wavelength monitor light receiving element for receiving the laser beam transmitted through the light source, and a power monitor light receiving element provided between the light emitting element and the optical filter for receiving a part of the laser beam output from the light emitting element. It is characterized by having.

It is also possible to have a parallel lens for collimating the laser light outputted from the light emitting element, and the power monitor light receiving element may be arranged between the parallel lens and the optical filter.

It is also possible to have a parallel lens for collimating the laser light output from the light emitting element, and the power monitor light receiving element may be arranged between the light emitting element and the parallel lens.

An optical fiber that receives the laser light output from the light emitting element and sends it out to the outside, and is arranged between the light emitting element and the optical fiber, and outputs the laser light output from the light emitting element to the optical fiber side. And a first optical branching member that branches to the optical filter side.

The light receiving element for power monitor is the first
It may be arranged between the light branching member and the optical filter, or may be arranged between the light emitting element and the first light branching member.

A light emitting element that outputs laser light, a second light branching member that branches the laser light output from the light emitting element into two directions, and a second light branching member that is branched by the second light branching member and are different from each other. First and second optical filters that transmit only laser light in a wavelength band, and the first and second optical filters
Is provided between the light emitting element and the first or second optical filter, and is output from the light emitting element, and the first and second wavelength monitoring light receiving elements that respectively receive the laser beams transmitted through the optical filter. A power monitor light-receiving element that receives a part of the generated laser light may be included.

A first optical transmitter of the present invention is a laser which is output from the light emitting element based on the optical module described above and signals output from the wavelength monitor light receiving element and the power monitor light receiving element. A first controller that controls the oscillation wavelength of light to be fixed to a predetermined wavelength, and controls the output of laser light output from the light emitting element based on a signal output from the light receiving element for power monitoring. Second
And a control unit of.

A second optical transmitter of the present invention is a laser output from the light emitting element based on the optical module described above and signals output from the first and second wavelength monitor light receiving elements. A first controller that controls the oscillation wavelength of light to be fixed to a predetermined wavelength, and controls the output of laser light output from the light emitting element based on a signal output from the light receiving element for power monitoring. And a second control unit that operates.

The WDM optical transmitter of the present invention is characterized by having a plurality of the optical transmitters described above and wavelength-multiplexing and transmitting the optical signals output from these optical transmitters.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing a configuration of an optical transmitter according to a first exemplary embodiment of the present invention, and FIG. 2 is a side view showing a configuration of an optical transmitter according to a first exemplary embodiment of the present invention.

As shown in FIGS. 1 and 2, the first aspect of the present invention is as follows.
The optical transmitter according to the example of the embodiment includes a light emitting element 1 such as a semiconductor laser diode that outputs laser light, and a rear end face (left side in FIG. 1) of the laser light output from the light emitting element 1.
The parallel lens 2 that makes the laser light for monitoring output from the laser light parallel, the optical filter 3 that transmits only the laser light in a predetermined wavelength band that is parallel by the parallel lens 2, and the laser light that has passed through the optical filter 3. It is provided between the wavelength monitor light receiving element 4 such as a photodiode for receiving the light, the parallel lens 2 and the optical filter 3, and the laser light output from the light emitting element 1 is emitted from the optical axis L (dotted line in FIG. 2) downward. Direction (Y direction)
A power monitor light receiving element 5 such as a photodiode that receives light at a position deviated from the position, a temperature adjusting unit 6 such as a Peltier element that controls the temperature of the light emitting element 1, and a wavelength monitoring light receiving element 4
Also, based on the signal output from the power monitor light-receiving element 5, a first adjustment temperature is controlled by the temperature adjustment unit so that the emission wavelength of the laser light output from the light-emitting element 1 is fixed to a predetermined wavelength. The controller 7 and the second controller 8 that controls the output of the laser light output from the light emitting element 1 based on the signal output from the power monitor light receiving element 5, and the front end face of the light emitting element 1 (see FIG. 1 has a laser beam output from the right side) and emits the laser beam to the outside, and a package 10 that hermetically seals the inside.

Here, the optical filter 3 and the wavelength monitor light receiving element 4 constitute the wavelength monitor section 11, and the light emitting element 1,
The optical module M includes the wavelength monitor unit 11, the temperature adjustment unit 6, and the optical fiber 9, and is surrounded by a dotted line in FIG. 1.

The wavelength monitor light-receiving element 4 is fixed on the first PD carrier 12. First PD carrier 12
The fixed surface 12a is formed with a downward slope toward the light emitting element 1 side in order to suppress reflection on the light emitting element 1. Further, the power monitor light receiving element 5 is fixed on the second PD carrier 13. The fixed surface 13a of the second PD carrier 13 has a downward slope toward the light emitting element 1 side with respect to the optical axis L so that the reflected light on the upper surface of the LD carrier 14 is not coupled to the power monitor light receiving element 5. It is formed to be inclined (see FIG. 2).

The optical filter 3 has periodicity in the wavelength-transmitted light intensity characteristic, and the wavelength interval of each period is 100 G.
For example, a Fabry-Perot etalon having a frequency of Hz or less, a dielectric multilayer filter, or the like is used.

The light emitting element 1 is fixed on the LD carrier 14. Further, a temperature detection unit 15 such as a thermistor for detecting the temperature of the light emitting element 1 is installed on the LD carrier 14.

Further, the LD carrier 14 and the wavelength monitor 1
1 is fixed on the base 16. First control unit 7
Is an input of two PD currents output from the wavelength monitor light receiving element 4 and the power monitor light receiving element 5, and the wavelength of the light output from the sending element 1 is determined based on the difference voltage or voltage ratio between them. The temperature detected by the temperature detecting unit 15 is controlled by the temperature adjusting unit 6 so as to be constant.

The second controller 8 inputs the PD current output from the power monitor light receiving element 5 and, based on the value, injects the injection current into the light emitting element 1 into the APC (Auto P
owerControl) Control.

On the front side (right side in FIG. 1) of the light emitting element 1,
A parallel lens 17 for collimating the laser light output from the front end face is provided. Further, on the front side of the parallel lens 17, an optical isolator 18 that blocks return light to the light emitting element 1 is provided. The optical isolator 18 is a well-known one that is configured by combining, for example, a polarizer and a Faraday rotator.

Inside the flange portion 10a formed on the side portion of the package 10, a window portion 19 through which the light passed through the optical isolator 18 is incident, and a condenser lens for condensing the laser light on the end face of the optical fiber 9. (Second lens) 20 is provided. The condenser lens 20 is held by a lens holder 21 fixed to the end of the flange portion 10a by YAG laser welding, and a metal slide ring 22 is fixed to the end of the lens holder 21 by YAG laser welding.

The optical fiber 9 is held by a ferrule 23, and the ferrule 23 is fixed inside the slide ring 22 by YAG laser welding.

A lid 24 (see FIG. 2) is provided on the package 10.
(Refer to FIG. 4), and the periphery of the package 10 is resistance-welded to hermetically seal the inside of the package 10.

The laser light output from the front end face of the light emitting element 1 is collimated by the parallel lens 17, condensed by the condenser lens 20 via the optical isolator 18 and the window portion 19, and incident on the optical fiber 9. It is sent to the outside.

On the other hand, the laser light output from the rear end face of the light emitting element 1 is made parallel by the parallel lens 2, and is received by the wavelength monitoring light receiving element 4 via the optical filter 3. The laser light made parallel by the parallel lens 2 is received by the power monitor light receiving element 5 arranged between the parallel lens 2 and the optical filter 3.

The first PD current and the second PD current output from the wavelength monitor light receiving element 4 and the power monitor light receiving element 5 are input to the first controller 7.

In the first control section 7, the first PD current and the second PD current are converted into voltages, the difference or ratio of the voltages is output by the comparator, and the temperature is adjusted based on the output control signal. A temperature control current for raising or lowering the temperature of the portion 6 is selectively output. Thereby, the emission wavelength of the laser light output from the light emitting element 1 can be controlled to a desired wavelength.

Further, the second control section 8 inputs the PD current output from the power monitor light receiving element 5 and, based on the value, injects the injection current to be injected into the light emitting element 1 into the APC.
(Auto Power Control) Control.

According to the first embodiment of the present invention, the wavelength monitor unit 11 comprises the optical filter 3 and the light receiving elements 4 and 5, and does not have a beam splitter such as a half mirror or a prism. Compared with this, the number of parts is reduced, and the structure of the wavelength monitor unit 11 is reduced. As a result, the overall size of the optical module M can be reduced.

Since the wavelength monitor 11 does not have a beam splitter such as a half mirror and a prism, the optical filter 3 and the like can be accurately arranged in the package 10 and the manufacturing time of the optical module M can be shortened. Can be achieved.

Since the wavelength monitor unit 11 does not have a beam splitter such as a half mirror or a prism, the error factors of the wavelength control due to the wavelength dependence and the polarization dependence of the laser light are reduced and the accuracy of the wavelength control is improved. Can be improved.

Since the wavelength monitor section 11 does not have a beam splitter such as a half mirror or a prism, it is possible to apply the optical filter 3 such as an etalon having a long wavelength cycle in the optical axis direction.

FIG. 3 is a side view schematically showing the configuration of the optical transmitter according to the second embodiment of the present invention. The second embodiment is characterized in that the power monitor light receiving element 5 is arranged between the light emitting element 1 and the parallel lens 2, and the other points are the same as those of the first embodiment. Is.

FIG. 4 is a plan view schematically showing the structure of the optical transmitter according to the third embodiment of the present invention. In the third embodiment, the wavelength monitor unit 11 is arranged on the front side (on the side of the optical fiber 9) of the light emitting element 1. That is, in the third embodiment, the laser light output from the light emitting element 1 is arranged between the light emitting element 1 and the optical fiber 9 and the optical fiber 9 is used.
Side and the optical filter 3 side, the first optical branching member 25 formed of a half mirror is provided, and the power monitor light receiving element 5 is disposed between the first optical branching member 25 and the optical filter 3. The other points are similar to those of the first embodiment.

FIG. 5 is a plan view schematically showing the configuration of the optical transmitter according to the fourth embodiment of the present invention. In the third embodiment, the laser light output from the light emitting element 1 is arranged between the light emitting element 1 and the optical fiber 9.
First light branching member 25 branching into the optical filter 3 side and the optical filter 3 side
The power monitor light receiving element 5 is characterized in that it is arranged between the light emitting element 1 and the first light branching member 25, and the other points are the same as in the first embodiment. .

FIG. 6 is a plan view schematically showing the structure of the optical transmitter according to the fifth embodiment of the present invention. In the fifth embodiment, the second light splitting member 26 is a prism that splits the laser light output from the light emitting element 1 into two directions.
And a first light that is branched by the second light branching member 26 and transmits only laser light of different wavelength bands.
And the second optical filters 3a and 3b, and the first and second wavelength monitoring light receiving elements 4a and 4b which respectively receive the laser beams transmitted through the first and second optical filters 3a and 3b.
And a power monitor light receiving element 5 that is provided between the light emitting element 1 and the second light branching member 26 and receives the laser light output from the light emitting element 1 at a position deviated from the optical axis. The features are the same as the first embodiment in other points. The power monitor light receiving element 5 may be arranged between the second optical branching member 26 and the first or second optical filter 3a, 3b.

In the fifth embodiment, the first and second wavelength monitors for receiving the laser light transmitted through the first and second optical filters 3a and 3b which transmit only the laser light in two different wavelength bands. Since the oscillation wavelength of the laser beam output from the light emitting element 1 is controlled to be fixed to a predetermined wavelength based on the signals output from the light receiving elements 4a and 4b for wavelength, the accuracy of wavelength control can be further improved. it can.

FIG. 7 is an explanatory diagram showing a WDM optical transmitter used in the wavelength division multiplexing communication system according to the sixth embodiment of the present invention.

As shown in FIG. 7, the wavelength division multiplexing communication system includes a plurality of optical transmitters 27 for transmitting optical signals and a plurality of channels of optical signals transmitted from the optical transmitters 27 for wavelength multiplexing. A multiplexer 28, a plurality of optical amplifiers 29 connected in a plurality of stages for amplifying and repeating the multiplexed optical signal wavelength-multiplexed by the multiplexer 28, and an optical signal amplified by the optical amplifier 29. It has a demultiplexer 30 that demultiplexes the wavelength for each channel, and a plurality of optical receivers 31 that receive the optical signals demultiplexed by the demultiplexer 30.

The WDM optical transmitter 32 according to the fifth embodiment of the present invention has a plurality of optical transmitters 31 according to the first to fifth embodiments, and outputs from these optical transmitters 31. An optical signal is wavelength-multiplexed and transmitted. Therefore, the optical transmitter 31
Since the wavelength of the optical signal oscillated from is stable, it is possible to construct a highly reliable high density WDM system.

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of technical matters described in the claims. For example, the power monitor light receiving element 5 may be arranged on the optical axis L, and the optical filter 3 may be arranged so as to be displaced from the optical axis L.

[0060]

According to the inventions according to claims 1 to 6, 8 and 10, the wavelength monitor section comprises an optical filter and a light receiving element,
Since it does not have a beam splitter such as a half mirror and a prism, the number of parts is reduced and the structure of the wavelength monitor is reduced as compared with the conventional one. As a result, the size of the entire optical module can be reduced.

Since the wavelength monitor does not have a beam splitter such as a half mirror and a prism, it becomes possible to accurately arrange the optical filter and the like in the package,
The manufacturing time of the optical module can be shortened.

Since the wavelength monitor does not have a beam splitter such as a half mirror or a prism, the error factors of the wavelength control due to the wavelength dependence or the polarization dependence of the laser light are reduced and the accuracy of the wavelength control is improved. Can be made.

Since the wavelength monitor section does not have a beam splitter such as a half mirror or a prism, an optical filter such as an etalon having a long wavelength cycle in the optical axis direction can be applied.

According to the inventions of claims 7, 9 and 10,
A first that receives only the laser beams of two different wavelength bands and a first that receives the laser beams that have passed through the second optical filter
Further, since the oscillation wavelength of the laser light output from the light emitting element is controlled to be fixed to a predetermined wavelength based on the signal output from the second wavelength monitoring light receiving element, the accuracy of wavelength control is further improved. be able to.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of an optical transmitter according to a first exemplary embodiment of the present invention.

FIG. 2 is a side view showing the configuration of the optical transmitter according to the first exemplary embodiment of the present invention.

FIG. 3 is a side view schematically showing a configuration of an optical transmitter according to a second exemplary embodiment of the present invention.

FIG. 4 is a plan view schematically showing a configuration of an optical transmitter according to a third exemplary embodiment of the present invention.

FIG. 5 is a plan view schematically showing a configuration of an optical transmitter according to a fourth exemplary embodiment of the present invention.

FIG. 6 is a plan view schematically showing a configuration of an optical transmitter according to a fifth exemplary embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a WDM optical transmitter used in a wavelength division multiplexing communication system according to a sixth embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a configuration of a conventional optical module and a conventional optical transmitter.

[Explanation of symbols]

M: Optical module 1: Light emitting element 2: Parallel lens 3: Optical filter 4: Photodetector for wavelength monitor 5: Light receiving element for power monitor 6: Temperature control unit 7: First control unit 8: Second control unit 9: Optical fiber 10: Package 11: Wavelength monitor section 12: First PD carrier 13: Second PD carrier 14: LD carrier 15: Temperature detector 16: Base 17: Parallel lens 18: Optical isolator 19: Window 20: Condensing lens 21: Lens holder 22: Slide ring 23: Ferrule 24: Lid 25: First light branching member 26: Second light splitting member 27: Optical transmitter 28: Combiner 29: Optical amplifier 30: Splitter 31: Optical receiver 32: WDM optical transmitter

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H037 AA01 BA03 BA32 DA02 DA03                       DA04                 5F073 AB27 AB28 BA02 FA02 FA25                       GA01 GA12 GA13 GA14 GA22                       GA23                 5F088 AA01 BA15 BA16 BB01 JA03                       JA12 JA13

Claims (10)

[Claims] 1. A light emitting element for outputting a laser beam, an optical filter for transmitting only a laser beam of a predetermined wavelength band outputted from the light emitting element, and a wavelength monitor for receiving the laser beam transmitted through the optical filter. An optical module comprising a light receiving element and a power monitor light receiving element provided between the light emitting element and the optical filter, for receiving a part of the laser light output from the light emitting element. 2. A parallel lens for collimating laser light output from the light emitting element, wherein the power monitor light receiving element is arranged between the parallel lens and the optical filter. The optical module according to claim 1. 3. A parallel lens for collimating a laser beam output from the light emitting element, wherein the power monitor light receiving element is arranged between the light emitting element and the parallel lens. The optical module according to claim 1. 4. An optical fiber, which is arranged between the light emitting element and the optical fiber and which receives the laser light output from the light emitting element and sends it to the outside, emits the laser light output from the light emitting element. A first optical branching member that branches into a fiber side and an optical filter side is provided.
4. The optical module according to any one of items 1 to 3. 5. The light receiving element for power monitoring is the first
The optical module according to claim 4, wherein the optical module is disposed between the optical branching member and the optical filter. 6. The optical module according to claim 4, wherein the power monitor light receiving element is arranged between the light emitting element and the first light branching member. 7. A light emitting element that outputs laser light, a second light branching member that branches the laser light output from the light emitting element into two directions, and a second light branching member that branches the laser light, and First and second optical filters that transmit only laser beams of different wavelength bands, and the first and second optical filters
Is provided between the light emitting element and the first or second optical filter, and is output from the light emitting element, and the first and second wavelength monitoring light receiving elements that respectively receive the laser beams transmitted through the optical filter. And a light receiving element for power monitoring, which receives a part of the generated laser light. 8. An optical module according to any one of claims 1 to 6, and an output from the light emitting element based on signals output from the wavelength monitor light receiving element and the power monitor light receiving element. A first controller for controlling the oscillation wavelength of the laser light to be fixed to a predetermined wavelength;
An optical transmitter comprising: a second control unit that controls the output of the laser light output from the light emitting element based on a signal output from the power monitoring light receiving element. 9. The oscillation wavelength of the laser light output from the light emitting element based on the signals output from the optical module according to claim 7 and the first and second wavelength monitor light receiving elements. The first to control so as to fix to a predetermined wavelength
And a second controller for controlling the output of the laser light output from the light emitting element based on the signal output from the power monitor light receiving element. . 10. A WDM optical transmitter, comprising a plurality of optical transmitters according to claim 8 or 9, wherein the optical signals output from these optical transmitters are wavelength-multiplexed and transmitted.