JP2010239079A - Semiconductor laser module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser module capable of miniaturizing a device, reducing power consumption and manufacturing cost, improving fluctuation of tracking error and lock wavelength, and precisely monitoring light emission. <P>SOLUTION: The semiconductor laser module M1 includes: a light emitting element 1; a light branching member 2 for branching laser light emitted from the light emitting element 1 into first and second laser light L1 and L2; a first light receiving element 3 for receiving the first laser light L1; a second light receiving element 4 for receiving the second laser light L2; and an optical fiber 5. In the module, the first light receiving element 3 as a photodiode on a surface of which a high reflection film 3a is coated reflects the received first laser light L1 to introduce into the optical fiber 5, and also converts part of the transmitted laser light into current to monitor. The second light receiving element 4 as the photodiode on a surface of which an antireflection film 4a is coated converts the received second laser light L2 into the current to monitor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor laser module mainly used in the field of optical communication.

  In general, a semiconductor laser module is used as a signal light source in optical communication, an excitation light source of an optical fiber amplifier, or the like.

  In a semiconductor laser module, it is necessary to stably control the optical output (power) and wavelength of laser light. Therefore, the laser beam emitted from the light emitting element is received by the light receiving element as the monitoring laser beam, and the light output and wavelength are detected and controlled. The laser beam for monitoring is emitted from the front end face of the light emitting element. A type using a laser beam (FFM (Front Facet Monitor)) and a type using a laser beam emitted from the rear end face of a light emitting element (RFM (Rear Facet Monitor)) are known.

FIG. 8 is an explanatory view showing an example of a conventional FFM type semiconductor laser module.
As shown in FIG. 8, a conventional semiconductor laser module M8 includes a light emitting element 50 such as a laser diode (semiconductor laser element), a parallel lens 51 that collimates laser light emitted from the light emitting element 50, and a parallel lens 51. A first beam splitter 52 that divides the laser beam paralleled by 2 into two, a first light receiving element 53 such as a photodiode that receives one of the laser beams branched by the first beam splitter 52, and A second beam splitter 54 that divides the other laser beam branched by the first beam splitter 52 into two, and one laser beam branched by the second beam splitter 54 into an optical filter 55 such as an etalon. Branched by a second light receiving element 56 such as a photodiode that receives light after passing through and a second beam splitter 54 The other laser beam having a condensing lens 57 for condensing light, and an optical fiber 58 to be sent to an external incident laser light condensed by the condenser lens 57.

  Between the parallel lens 51 and the first beam splitter 52, an optical isolator 59 for blocking reflected return light from the first beam splitter 52 is disposed.

  In the conventional semiconductor laser module M8, the light output is monitored by the first light receiving element 53, and the amount of drive current to the light emitting element 50 is adjusted by an APC (Auto Power Control) circuit, for example, based on the monitoring result. The light output is controlled to be constant.

The wavelength of the laser light is monitored from the amount of light received by the first light receiving element 53 and the second light receiving element 56, and based on the monitoring result, the temperature of the light emitting element 50 is measured by a temperature adjusting unit such as a Peltier module. Is adjusted so as to maintain a predetermined emission wavelength (lock wavelength) (see, for example, Patent Document 1).
JP 2002-185074 A

  In the conventional example, since two beam splitters are necessary, an increase in the number of components and an increase in the installation space for the components cause an increase in the size of the device, an increase in power consumption necessary for temperature adjustment, and an increase in manufacturing costs. There was a problem.

  Further, since the optical path length becomes long, the amount of fluctuation of the optical axis increases, and there is a problem that tracking error (rate of change of the optical output value of the laser light) and lock wavelength are likely to occur.

  Further, since the main laser beam guided to the optical fiber is not monitored, there is a problem that it is difficult to accurately monitor the optical output reflecting the deviation of the optical axis.

  The present invention has been made to solve the above-described problems, and can reduce the size of the apparatus, reduce power consumption and manufacturing cost, improve tracking errors and fluctuations in lock wavelength, and provide accurate optical output. An object of the present invention is to provide a semiconductor laser module capable of monitoring the above.

The first semiconductor laser module of the present invention includes a light emitting element, a light branching member that branches laser light emitted from the light emitting element into a first laser light and a second laser light, and the first laser light. In a semiconductor laser module having a first light receiving element that receives light, a second light receiving element that receives the second laser light, and an optical fiber,
The first light receiving element is coated with a highly reflective film on the surface thereof, reflects the received first laser light and guides it to the optical fiber, and monitors a part of the transmitted laser light,
The second light receiving element is coated with an antireflection film on the surface thereof, and monitors the received second laser light.
It is characterized by this.

  An optical filter that selectively transmits laser light of a predetermined wavelength may be disposed between the light branching member and the second light receiving element.

  The light branching member may be a plate-shaped beam splitter.

  The light branching member may be a cube-shaped beam splitter.

  The optical branching member may be an optical isolator including a polarizer that reflects laser light.

  An optical isolator for blocking reflected return light may be disposed between the light emitting element and the light branching member.

The second semiconductor laser module of the present invention includes a light emitting element, a first light receiving element that receives a first laser beam emitted from one end face of the light emitting element, and an emission from the other end face of the light emitting element. In a semiconductor laser module having a second light receiving element for receiving the second laser light and an optical fiber,
The first light receiving element is coated with a highly reflective film on the surface, reflects the received first laser light and guides it to the optical fiber, and monitors a part of the transmitted laser light,
The second light receiving element has a surface coated with an antireflection film, and monitors the received second laser light.
It is characterized by this.

  An optical filter that selectively transmits laser light having a predetermined wavelength may be disposed between the light emitting element and the second light receiving element.

  An optical isolator for blocking reflected return light may be disposed between the first light receiving element and the optical fiber.

  According to the first semiconductor laser module of the present invention, the first laser beam is reflected by the first light receiving element and guided to the optical fiber, so that there is one optical branching member (beam splitter) for branching the laser beam. As a result, the number of parts can be reduced and the installation space for the parts can be reduced. As a result, it is possible to reduce the size of the apparatus, reduce power consumption associated with temperature adjustment, and reduce manufacturing costs.

  Further, since the optical path length is shortened, the amount of fluctuation of the optical axis is reduced, and the tracking error and the fluctuation of the lock wavelength can be reduced.

  Furthermore, since the main laser light to be guided to the optical fiber is monitored, the optical output reflecting the deviation of the optical axis can be accurately monitored.

  According to the second semiconductor laser module of the present invention, since the first laser beam is reflected by the first light receiving element and guided to the optical fiber, it is an optical branching member for branching the laser beam. Is eliminated, the number of parts is further reduced, and the installation space for the parts can be reduced. As a result, it is possible to reduce the size of the apparatus, reduce power consumption associated with temperature adjustment, and reduce manufacturing costs.

It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 1st example of an embodiment of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 2nd Example of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 3rd Example of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 4th Example of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 5th Example of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 6th Example of this invention. It is explanatory drawing which shows an example of the semiconductor laser module which concerns on the 7th Example of this invention. It is explanatory drawing which shows an example of the conventional FFM type semiconductor laser module.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory view showing an example of a semiconductor laser module according to the first embodiment of the present invention.

  As shown in FIG. 1, the semiconductor laser module M1 according to the first embodiment of the present invention includes a light emitting element 1 and laser light emitted from the light emitting element 1 as a first laser light L1 and a second laser. A light branching member 2 that branches into the light L2, a first light receiving element 3 that receives the first laser light L1, a second light receiving element 4 that receives the second laser light L2, an optical fiber 5, It has the package 6 which accommodates these members, and the control part 7. FIG.

  The light emitting element 1 is a laser diode (semiconductor laser element) that emits laser light.

  Between the light emitting element 1 and the light branching member 2, a parallel lens 8 that collimates the laser light emitted from the light emitting element 1 and an optical isolator 9 that blocks reflected return light from the light branching member 2 are arranged. Has been.

  The light branching member 2 is a cube-shaped beam splitter 2a, which reflects a part of the incident laser light by 90 degrees and branches it to the first laser light L1, and transmits a part of the second laser light. Branches to the light L2.

  The first light receiving element 3 is a photodiode having a surface coated with a high reflection film 3a (HR film), reflects the received first laser light L1 to the optical fiber 5, and transmits a part thereof. The laser beam is converted into current and monitored. The reflectance of the first light receiving element 3 is determined by the light output of the main laser light, the light receiving sensitivity of itself, and the like.

  The second light receiving element 4 is a photodiode having a surface coated with an antireflection film 4a (AR film), and monitors the received second laser light L2 by converting it into a current.

  An optical filter 10 such as an etalon that selectively transmits laser light having a predetermined wavelength is disposed between the light branching member 2 and the second light receiving element 4.

  A condensing lens 11 for condensing the first laser beam L1 and optically coupling it to the optical fiber 5 is disposed between the first light receiving element 3 and the optical fiber 5.

  The control unit 7 controls the light output to be constant by adjusting the amount of drive current to the light emitting element 1 by using, for example, an APC circuit based on the monitoring result by the first light receiving element 3.

  The control unit 7 monitors the wavelength of the laser light from the amount of light received by the first light receiving element 3 and the second light receiving element 4, and based on the monitoring result, for example, by a temperature adjusting unit such as a Peltier module By controlling the temperature of the light emitting element 1, control is performed so as to maintain a predetermined emission wavelength.

  Next, the operation of the semiconductor laser module M1 according to the first embodiment of the present invention will be described.

  The laser light emitted from the light emitting element 1 is made parallel by the parallel lens 8, passes through the optical isolator 9, and enters the light branching member 2.

  The incident laser light is branched into the first laser light L1 and the second laser light L2 by the light branching member 2.

  The first laser beam L1 branched by the light branching member 2 is received by the first light receiving element 3, reflected by the high reflection film 3a coated on the surface, and a part of the transmitted laser beam is a current. Is converted to and monitored.

  The first laser light L1 reflected by the first light receiving element 3 is condensed by the condenser lens 11, enters the optical fiber 5, and is transmitted to the outside.

  On the other hand, the second laser beam L2 branched by the light branching member 2 passes through the optical filter 10, is received by the second light receiving element 4, is converted into a current, and is monitored.

  According to the first embodiment of the present invention, since the first laser beam L1 is reflected by the first light receiving element 3 and guided to the optical fiber 5, an optical branching member (beam splitter) for branching the laser beam is used. ) Is sufficient, the number of parts is reduced, and the installation space for the parts can be reduced. As a result, it is possible to reduce the size of the apparatus, reduce power consumption associated with temperature adjustment, and reduce manufacturing costs.

  Further, since the optical path length is shortened, the amount of fluctuation of the optical axis is reduced, and the tracking error and the fluctuation of the lock wavelength can be reduced.

  Furthermore, since the main laser light to be guided to the optical fiber 5 is monitored, the optical output reflecting the deviation of the optical axis can be accurately monitored.

FIG. 2 is an explanatory view showing an example of a semiconductor laser module according to the second embodiment of the present invention.
As shown in FIG. 2, in the semiconductor laser module M <b> 2 according to the second embodiment of the present invention, an optical isolator 9 for blocking reflected return light is provided between the first light receiving element 3 and the optical fiber 5. Is arranged.

  In the case where the optical isolator 9 is not disposed between the light emitting element 1 and the light branching member 2, the light branching member 2 has an incident surface slightly inclined (about 2 to 4 degrees) with respect to the optical axis. It is necessary to arrange and prevent the reflected return light from the light branching member 2.

FIG. 3 is an explanatory view showing an example of a semiconductor laser module according to the third embodiment of the present invention.
As shown in FIG. 3, in the semiconductor laser module M3 according to the third embodiment of the present invention, a plate-shaped beam splitter 2b is used as the optical branching member 2 instead of the beam-shaped beam splitter 2a. .

  FIG. 4 is an explanatory view showing an example of a semiconductor laser module according to the fourth embodiment of the present invention.

  As shown in FIG. 4, in the semiconductor laser module M4 according to the fourth embodiment of the present invention, a plate-shaped beam splitter 2b is used as the light branching member 2, and a part of the incident laser light is used as the optical axis. On the other hand, the light is reflected at a predetermined angle θ1 and branched into the second laser light L2, and part of the light is transmitted and branched into the first laser light L1.

  Note that a cube-shaped beam splitter 2 a may be used as the light branching member 2.

  FIG. 5 is an explanatory view showing an example of a semiconductor laser module according to the fifth embodiment of the present invention.

  As shown in FIG. 5, in the semiconductor laser module M5 according to the fifth embodiment of the present invention, the optical branching member 2 uses an optical isolator 2c including a polarizer 12 that reflects the laser light and is incident thereon. A part of the laser light is reflected to the installation side (right side in FIG. 5) of the optical fiber 5 at a predetermined angle θ2 with respect to the optical axis and branched to the second laser light L2, and part of the laser light is transmitted through the first optical fiber 5. Branches into one laser beam L1.

  An optical isolator 2c including a polarizer 12 that reflects laser light is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-142110 (semiconductor laser module) invented by the present inventors and filed by the present applicant. .

  According to the fifth embodiment of the present invention, since the optical branching member 2c including the polarizer 12 that reflects the laser light also serves as an optical isolator and a beam splitter, the number of components can be further reduced. The installation space for parts can be further reduced. As a result, the size of the apparatus can be reduced, the power consumption associated with the temperature adjustment, and the manufacturing cost can be further reduced.

  FIG. 6 is an explanatory view showing an example of a semiconductor laser module according to the sixth embodiment of the present invention.

  As shown in FIG. 6, in the semiconductor laser module M6 according to the sixth embodiment of the present invention, the optical branching member 2 uses an optical isolator 2c including a polarizer 12 that reflects the laser light and is incident thereon. A part of the laser light is reflected at a predetermined angle θ3 on the side opposite to the installation side of the optical fiber 5 (left side in FIG. 6) and branched into the second laser light L2, and part of the laser light is transmitted through the first laser beam L2. The laser beam L1 is branched.

  In the sixth embodiment of the present invention, a part of the incident laser beam is reflected by the optical branching member 2c to the side opposite to the installation side of the optical fiber 5, so that from the light emitting element 1 to the optical fiber 5 is reflected. The optical path length can be further shortened, and tracking errors and fluctuations in lock wavelength can be further reduced.

  FIG. 7 is an explanatory view showing an example of a semiconductor laser module according to a seventh embodiment of the present invention.

  As shown in FIG. 7, the semiconductor laser module M7 according to the seventh embodiment of the present invention is an RFM type semiconductor laser module, and emits light from the light emitting element 1 and one end face of the light emitting element 1. A first light receiving element 3 that receives the first laser light L1, a second light receiving element 4 that receives the second laser light L2 emitted from the other end face of the light emitting element 1, and an optical fiber 5. .

  An optical filter 10 such as an etalon that selectively transmits laser light having a predetermined wavelength is disposed between the light emitting element 1 and the second light receiving element 4.

  Between the light emitting element 1 and the first light receiving element 3, a first parallel lens 8 a that makes the first laser light L 1 emitted from one end face of the light emitting element 1 parallel is arranged.

  Between the light emitting element 1 and the optical filter 10, the 2nd parallel lens 8b which makes the 2nd laser beam L2 radiate | emitted from the other end surface of the light emitting element 1 parallel is arrange | positioned.

  An optical isolator 9 for blocking the reflected return light is disposed between the first light receiving element 3 and the optical fiber 5 (the condensing lens 11 in the example of FIG. 7).

  In the seventh embodiment of the present invention, the laser light is branched because it is an RFM type semiconductor laser module and the first laser beam L1 is reflected by the first light receiving element 3 and guided to the optical fiber 5. Therefore, the light branching member 2 is not required, the number of parts is further reduced, and the installation space for the parts can be reduced. As a result, it is possible to reduce the size of the apparatus, reduce power consumption associated with temperature adjustment, and reduce manufacturing costs.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical matters described in the claims.

  The present invention is used in, for example, a semiconductor laser module used as a signal light source in optical communication, a pumping light source of an optical fiber amplifier, or the like.

M1 to M7: Semiconductor laser module L1: First laser beam L2: Second laser beam 1: Light emitting element 2: Optical branching member 2a: Cube-shaped beam splitter 2b: Flat plate-shaped beam splitter 2c: Provided with a polarizer Optical isolator 3: first light receiving element 3a: high reflection film 4: second light receiving element 4a: antireflection film 5: optical fiber 6: package 7: control unit 8: parallel lens 8a: first parallel lens 8b : Second parallel lens 9: optical isolator 10: optical filter 11: condenser lens 12: polarizer

Claims (9)

A light emitting element, a light branching member that branches the laser light emitted from the light emitting element into a first laser light and a second laser light, a first light receiving element that receives the first laser light, and In a semiconductor laser module having a second light receiving element that receives the second laser light and an optical fiber,
The first light receiving element is coated with a highly reflective film on the surface thereof, reflects the received first laser light and guides it to the optical fiber, and monitors a part of the transmitted laser light,
The second light receiving element is coated with an antireflection film on the surface thereof, and monitors the received second laser light.
A semiconductor laser module.   2. The semiconductor laser module according to claim 1, wherein an optical filter that selectively transmits laser light having a predetermined wavelength is disposed between the light branching member and the second light receiving element.   3. The semiconductor laser module according to claim 1, wherein the optical branching member is a flat beam splitter.   3. The semiconductor laser module according to claim 1, wherein the optical branching member is a cube-shaped beam splitter.   The semiconductor laser module according to claim 1, wherein the optical branching member is an optical isolator including a polarizer that reflects laser light.   5. The semiconductor laser according to claim 1, wherein an optical isolator for blocking reflected return light is disposed between the light emitting element and the light branching member. module. A first light-receiving element that receives a first laser beam emitted from one end face of the light-emitting element, and a second light-receiving element that receives a second laser light emitted from the other end face of the light-emitting element. In a semiconductor laser module having two light receiving elements and an optical fiber,
The first light receiving element is coated with a highly reflective film on the surface, reflects the received first laser light and guides it to the optical fiber, and monitors a part of the transmitted laser light,
The second light receiving element has a surface coated with an antireflection film, and monitors the received second laser light.
A semiconductor laser module.   8. The semiconductor laser module according to claim 7, wherein an optical filter that selectively transmits laser light having a predetermined wavelength is disposed between the light emitting element and the second light receiving element.   9. The optical isolator for blocking reflected return light is disposed between the first light receiving element and the optical fiber. Semiconductor laser module.

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