JP2000347049A - Light source module and light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and easy-to-manufacture light source module or the like capable of stably outputting a high level beam of light. SOLUTION: A laser beam with a wavelength λ1 selected by an optical multiplexing circuit 215 is generated by an optical resonator constituted of the reflection surface 11a of a semiconductor laser light source 11 and a chirped grating 226. Similarly, a laser beam with a wavelength λ2 is generated by an optical resonator constituted of the reflection surface 12a of a semiconductor laser light source 12 and the chirped grating 226. A laser beam with a wavelength λ3 is generated by an optical resonator constituted of the reflection surface 13a of a semiconductor laser light source 13 and the grating 226. A laser beam with a wavelength λ4 is generated by an optical resonator constituted of the reflection surface 14a of a semiconductor laser light source 14 and the grating 226. The light with a wavelength λ1-λ4 are multiplexed and outputted from an output terminal 206.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source module and a light source unit suitably used as an excitation light source in an optical fiber amplifier.

[0002]

2. Description of the Related Art Wavelength division multiplexing (WDM) for multiplexing multi-wavelength signal light for optical transmission.
g) In transmission, it is desired to increase the distance between repeaters for optically amplifying signal light and increase the wave number (channel number) of multiplexed signal light. From such a viewpoint, an optical amplifier that performs optical amplification of signal light is required to have a high gain and a wide band. In order to increase the gain of the optical amplifier, studies have been made to increase the output of the pump light source in the optical amplifier.

[0003] For example, the document "K. Tanaka, et al.," Low
loss integrated Mach-Zehnder-interferometer-type e
ight-wavelength multiplexer for 1480nm band pumpin
g ", OFC'99, Technical Digest, TuH5 (1999)", in an optical fiber amplifier, a high-level excitation light is supplied from an excitation light source to an amplification optical fiber (a rare-earth element (eg, Er element) -doped optical fiber). By doing so, a technique for increasing the gain of optical amplification of signal light in the amplification optical fiber is described. The light source module used as an excitation light source described in this document includes a plurality of sets of semiconductor laser light sources, an optical fiber grating element, and an optical multiplexer. The semiconductor laser light source and the optical fiber grating element of each set constitute a narrow-band optical resonator whose oscillation center wavelengths are slightly different from each other. The optical multiplexer multiplexes the light of each wavelength output from each optical resonator, and outputs the multiplexed light as excitation light. By doing so, high-level excitation light is output from this light source module. The pump light supplied to the amplification optical fiber of the optical amplifier is not so important in spectral characteristics and spectral width. For example, when the amplification optical fiber is an Er element-doped optical fiber, the excitation light is effective in a wavelength range of about 1.45 μm to 1.50 μm.

[0004]

However, the light source module described in the above document has a large number of components and a large overall size because an optical fiber grating element is connected to each semiconductor laser. Also, in order to output a high level of light from the light source module, it is important to match the reflection characteristics of the optical fiber grating element with the multiplexing characteristics of the optical multiplexer. It is difficult. Even if the reflection characteristic of the optical fiber grating element and the multiplexing characteristic of the optical multiplexer can be matched, these characteristics have temperature dependence, and the optical fiber grating element and the optical multiplexing element When the ambient temperature changes, the reflection center wavelength of the optical fiber grating element and the transmission center wavelength of the optical multiplexer become different from each other, and as a result, the output from the light source module is changed. The power of the emitted light is reduced. In particular, when the spectrum width of the oscillation center wavelength in each optical resonator is narrow,
The output light power fluctuates greatly. In order to keep the power of the light output from the light source module constant, it is necessary to perform temperature control or temperature compensation for each of the optical fiber grating element and the optical multiplexer. Is included, the size of the light source module is further increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a small light source module which can stably output a high level of light and is easy to manufacture, and a light source module which is even higher than this light source module. An object of the present invention is to provide a light source unit capable of stably outputting light of a level.

[0006]

The light source module according to the present invention comprises: (1) an optical multiplexing circuit for multiplexing lights having different wavelengths input to a plurality of input ports, and (2) an optical multiplexing circuit. In a wavelength band including each wavelength of the light to be waved, reflecting means for reflecting a part of the combined light and transmitting the remainder to an output port, and (3) a reflecting surface and an emitting surface, Light is input and output between the exit surface and each of the plurality of input ports, and the reflection surface and the reflection means include a plurality of light emitting elements constituting an optical resonator.

In particular, this optical multiplexing circuit is preferably a Mach-Zehnder interferometer type circuit or an arrayed waveguide diffraction grating type circuit. Preferably, the reflecting means is a reflecting member provided between or between the optical multiplexing circuit and the output port, or a chirped grating provided between the optical multiplexing circuit and the output port. is there. In addition, it is more preferable that the optical multiplexing circuit and the reflection means are integrated on a planar waveguide in terms of miniaturization.

According to this light source module, laser oscillation occurs in each optical resonator constituted by the reflection means and the reflection surface of each light emitting element (for example, a semiconductor laser light source), and light of a predetermined wavelength is obtained. The light of each wavelength obtained by each optical resonator is multiplexed by an optical multiplexing circuit, and the multiplexed light is output from an output port. Since the oscillation center wavelength of each optical resonator matches the transmission center wavelength of an optical multiplexing circuit provided in the optical resonator and having a wavelength selecting function, a high-level optical output is always obtained, and manufacturing is easy. Also, since only one reflecting means needs to be provided, the number of parts is small,
It is possible to reduce the size and cost. When the optical multiplexing circuit is a Mach-Zehnder interferometer type circuit or an arrayed waveguide diffraction grating type circuit, this optical multiplexing circuit is suitable because it has a wavelength selecting function. Further, the Mach-Zehnder interferometer type circuit is suitable in that it has low loss, and the array waveguide diffraction grating type circuit is suitable in that it can multiplex light of a larger wave number.

The light source unit according to the present invention receives (1) the light output from the output port of each of the two polarization-maintaining light source modules and (2) the light output from the respective output ports of the two light source modules. And a polarization combiner for combining the polarized light and outputting the combined light. According to this light source unit, the light output from the output port of each of the two types of light source modules is obtained by multiplexing light of multiple wavelengths, and is polarized in a certain direction. The signal is input to the polarization combiner while being maintained, and is then polarized and combined by the polarization combiner and output. This light source unit can output light with higher power than the light output from a single light source module.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) First, a first embodiment of a light source module according to the present invention will be described. FIG.
1 is a configuration diagram of a light source module according to a first embodiment. The light source module 1 according to the present embodiment includes four semiconductor laser light sources 11 to 14, a four-input one-output optical multiplexing circuit 215, and a chirped grating element 226.

The semiconductor laser light source 11 has a reflection surface 11a and an emission surface 11b, and can input and output light via the emission surface 11b. The semiconductor laser light source 12 has a reflection surface 12a and an emission surface 12b.
Input / output of light is possible via 2b. The semiconductor laser light source 13 has a reflection surface 13a and an emission surface 13b, and light can be input and output through the emission surface 13b. The semiconductor laser light source 14 has a reflection surface 14a and an emission surface 14b, and light can be input and output through the emission surface 14b. In addition, these semiconductor laser light sources 11 to
14 may emit light in the same wavelength band.

Input ports 201-204 and output port 2
06, an optical multiplexing circuit 215 and a chirped grating element 226 are provided. Input port 2
Reference numeral 01 is connected to the emission surface 11b of the semiconductor laser light source 11 via an optical fiber. Similarly, input port 20
2 is connected to the emission surface 12b of the semiconductor laser light source 12 via an optical fiber. The input port 203 is connected to the emission surface 13b of the semiconductor laser light source 13 via an optical fiber. The input port 204 is connected to the emission surface 14b of the semiconductor laser light source 14 via an optical fiber.

The optical multiplexing circuit 215 includes Mach-Zehnder interferometer type fiber couplers 215 _{1 to} 215 ₃ . The fiber coupler 215 ₁ multiplexes the light of the wavelength λ ₁ input to the input port 201 and the light of the wavelength λ ₂ input to the input port 202, and outputs the multiplexed light to the fiber coupler 215 ₃ . The fiber coupler 215 ₂ is connected to the input port 203
The light having the wavelength λ ₃ input to the input port 204 and the light having the wavelength λ ₄ input to the input port 204 are multiplexed and output to the fiber coupler 215 ₃ . Further, the fiber coupler 215 ₃ includes light of wavelengths λ ₁ and λ ₂ arriving from the fiber coupler 215 ₁ ,
Wavelengths λ ₃ and λ ₄ arriving from fiber coupler 215 ₂
And outputs the combined light to the output port 256. That is, the optical multiplexing circuit 215 is connected to the input ports 201 to 2.
The lights of wavelengths λ _{1 to} λ ₄ input to the optical path 04 are multiplexed, and the multiplexed light is output to the output port 256.

When light is input to the output port 256, the optical multiplexing circuit 215 demultiplexes the light and outputs a light having a wavelength λ.
₁ is output to the input port 201, the light of wavelength λ ₂ is output to the input port 202, and the light of wavelength λ ₃ is output to the input port 20.
3 and the light of wavelength λ ₄ is output to the input port 204. As described above, the optical multiplexing circuit 215 that multiplexes and demultiplexes light having different wavelengths λ _{1 to} λ ₄ can reduce a loss associated with multiplexing and demultiplexing.

The chirped grating element 226 is
For example, the refractive index modulation is induced by irradiating the optical fiber with ultraviolet light through a phase grating mask, and the grating interval of the refractive index modulation is continuously changing. A part (for example, 5% to 20%) of light having a wavelength corresponding to the modulation grating interval is reflected. The reflection wavelength band of the chirped grating 226 is
15 includes wavelengths that can be combined and demultiplexed. Therefore, the chirped grating 226 reflects a part of the light output from the output port 256 of the optical multiplexing circuit 215, and transmits the remainder toward the output port 206.

The light source module 1 according to this embodiment operates as follows. Reflecting surface 1 of semiconductor laser light source 11
1a and the chirped grating 226, across the optical multiplexing circuit 215 having a wavelength selecting function therebetween constitute an optical resonator, emits a laser beam having a wavelength lambda ₁ by the optical resonator. Reflection surface 12a of semiconductor laser light source 12
And the chirped grating 226, across the optical multiplexing circuit 215 having a wavelength selecting function therebetween constitute an optical resonator, emits a laser beam having a wavelength lambda ₂ by the optical resonator. The reflection surface 13a of the semiconductor laser light source 13 and the chirped grating 226 constitute an optical resonator with an optical multiplexing circuit 215 having a wavelength selection function interposed therebetween, and the optical resonator forms a laser of wavelength λ ₃ . Emits light. Further, the reflection surface 14a of the semiconductor laser light source 14 and the chirped grating 226 constitute an optical resonator with an optical multiplexing circuit 215 having a wavelength selecting function interposed therebetween, and the wavelength λ ₄ Oscillate. Since the chirped grating 226 is common to the optical resonators, the light output from the chirped grating 226 toward the output port 206 is a light obtained by multiplexing the light of wavelengths λ _{1 to} λ _4. It is.

In the light source module 1 according to the present embodiment,
The light of each of the wavelengths λ _{1 to} λ ₄ oscillated and output by each optical resonator is converted to a Mach-Zehnder interferometer type fiber coupler 21.
The 5 _{1-215 3} optical multiplexing circuit 215 configured to include a is of demultiplexing a wavelength capable. Light of each wavelength is multiplexed and output from the chirped grating element 226 shared by each optical resonator. Therefore, the light source module 1 according to the present embodiment can combine light with high efficiency and output high output light, and is easy to manufacture.

When the temperature changes, the transmission center wavelength of the optical multiplexing circuit 215 changes, and the oscillation center wavelength of each optical resonator also changes. However, in this embodiment, the optical multiplexing circuit 215 having the wavelength selection function exists in each resonator, and the chirped grating element 226 has the wavelength λ ₁ to λ ₁ .
Since a part of the light is reflected and the rest is transmitted in the wavelength band including λ ₄ , the transmission center wavelength of the optical multiplexing circuit 215 always coincides with the oscillation center wavelength of each optical resonator. Therefore, without performing special temperature control,
The optical multiplexing circuit 215 can maintain a favorable multiplexing state, and the light source module 1 can stably output high-level light.

Further, the light source module 1 according to the present embodiment
Means one chirped grating 2 as a reflection means
Since only 26 is provided, the number of parts is reduced, and downsizing and cost reduction can be achieved.

(Second Embodiment) Next, a second embodiment of the light source module according to the present invention will be described. FIG.
FIG. 4 is a configuration diagram of a light source module according to a second embodiment. The light source module 2 according to the present embodiment includes four semiconductor laser light sources 11 to 14 and a four-input one-output optical multiplexer 20.
B. Semiconductor laser light sources 11 to 14
Are the same as those in the first embodiment.

The optical multiplexer 20B has input ports 201 to 2
The input side channel waveguides 211 to 214, the optical multiplexing circuit 215, and the output side channel waveguide 216 are provided between the output port 206 and the output port 206.
Is provided with a reflection film 227. This optical multiplexer 20B
Are input ports 201-204, output port 206, input-side channel waveguides 211-214, optical multiplexing circuit 21
5. The output-side channel waveguide 216 and the reflection film 227 are integrated on a planar waveguide.

The input port 201 of the optical multiplexer 20B is connected to the emission surface 11b of the semiconductor laser light source 11 via an optical fiber or directly. The input-side channel waveguide 211 is connected to the input port 201 and the first
Between the input terminal 251 and the input terminal 251. Similarly, the input port 202 is connected to the emission surface 12 b of the semiconductor laser light source 12.
And via an optical fiber or directly. The input-side channel waveguide 212 is provided between the input port 202 and the second input terminal 252 of the optical multiplexing circuit 215. The input port 203 is connected to the emission surface 13b of the semiconductor laser light source 13 via an optical fiber or directly. The input side channel waveguide 213 is connected to the input port 2
03 and the third input terminal 253 of the optical multiplexing circuit 215. The input port 204 is connected to the emission surface 14b of the semiconductor laser light source 14 via an optical fiber or directly. Input side channel waveguide 214
Is provided between the input port 204 and the fourth input terminal 254 of the optical multiplexing circuit 215.

As the optical multiplexing circuit 215, a Mach-Zehnder interferometer type circuit or an array waveguide diffraction grating type circuit is suitably used, and the wavelengths λ _{1 to} λ ₄ inputted to the input terminals 251 to 254 are used.
And outputs the multiplexed light to the output terminal 256. The Mach-Zehnder interferometer type circuit is suitable in that an optical multiplexing function can be realized with low loss. Further, the arrayed waveguide grating type circuit is suitable in that light of many wavelengths can be multiplexed. The wavelengths λ _{1 to} λ ₄ are different from each other. The output channel waveguide 216 guides the light output from the output end 256 of the optical multiplexing circuit 215 to the output port 206. The light output from the output port 206 is introduced into the optical fiber 30.

On the other hand, the optical multiplexing circuit 215
When light is input to 56, the light is demultiplexed, the light of wavelength λ ₁ is output to the first input terminal 251, and the light of wavelength λ ₂ is output to the _second input terminal 251.
, The light of wavelength λ ₃ is output to the third input terminal 253, and the light of wavelength λ ₄ is output to the fourth input terminal 2.
Output to 54.

FIGS. 3 and 4 show the optical multiplexing circuit 2 respectively.
It is a figure explaining 15 circuit examples. The optical multiplexing circuit 215 shown in FIG. 3 is a Mach-Zehnder interferometer type circuit, and is a channel waveguide 231 for guiding the light of wavelength λ ₁ input to the first input terminal 251 and input to the second input terminal 252. Channel waveguide 232 for guiding the light having the wavelength λ ₂ ,
And a channel waveguide 234 for guiding the light of wavelength λ ₃ input to the input terminal 253 of the second input terminal 253 and the light of wavelength λ ₄ input to the fourth input terminal 254.
Is provided. The channel waveguide 231 and the channel waveguide 232 constitute a Mach-Zehnder interferometer 235, and the Mach-Zehnder interferometer 235
The light of the wavelength λ ₁ guided through the channel 31 and the light of the wavelength λ ₂ guided through the channel waveguide 232 are multiplexed. Channel waveguide 2
33 and the channel waveguide 234 constitute a Mach-Zehnder interferometer 236, and the Mach-Zehnder interferometer 23
6 combines the light of wavelength λ ₃ guided through the channel waveguide 233 and the light of wavelength λ ₄ guided through the channel waveguide 234. Further, the channel waveguide 232 and the channel waveguide 234 constitute a Mach-Zehnder interferometer 237. The Mach-Zehnder interferometer 237 includes light of wavelengths λ ₁ and λ ₂ guided through the channel waveguide 232, The light of wavelengths λ ₃ and λ ₄ guided through 233 is multiplexed, and the multiplexed light is output to the output terminal 256.

An optical multiplexing circuit 215 shown in FIG. 4 is an arrayed waveguide diffraction grating type circuit, and is a channel waveguide 24 for guiding light of wavelength λ ₁ inputted to a first input terminal 251.
1. Channel waveguide 242 for guiding light of wavelength λ ₂ input to second input end 252, channel waveguide 24 for guiding light of wavelength λ ₃ input to third input end 253
3. a channel waveguide 244 for guiding light of wavelength [lambda] ₄ input to the fourth input terminal 254, and channel waveguides 241 to 241.
A first slab waveguide 245 connected to the first slab waveguide 245, an array waveguide 246 including a plurality of channel waveguides connected to the first slab waveguide 245 and having different optical path lengths, and connected to the array waveguide 246. Second slab waveguide 2
47, and a channel waveguide 248 connected to the second slab waveguide 247. This arrayed waveguide grating circuit converts the light of wavelengths λ _{1 to} λ ₄ input to the channel waveguides 241 to 244 into the first slab waveguide 245, the arrayed waveguide section 246, and the second slab waveguide 247. Are sequentially guided and then multiplexed until input to the channel waveguide 248, and the multiplexed light is output to the output terminal 256.
Output to

The reflection film 227 reflects a part (for example, 5% to 20%) of the light output from the output end 256 of the optical multiplexing circuit 215 and reaching the output port 206 via the output side channel waveguide 216. The remaining part is transmitted toward the optical fiber 30. The reflection wavelength band of the reflection film 227 includes a wavelength that can be multiplexed / demultiplexed by the optical multiplexing circuit 215.

That is, in this embodiment, the reflection surface 11a of the semiconductor laser light source 11 and the reflection film 227 oscillate a laser beam having a wavelength λ ₁ with an optical multiplexing circuit 215 having a wavelength selection function interposed therebetween. It constitutes an optical resonator. The reflection surface 12a of the semiconductor laser light source 12 and the reflection film 227 form an optical resonator that oscillates a laser beam having a wavelength of λ ₂ with an optical multiplexing circuit 215 having a wavelength selection function interposed therebetween. The reflecting surface 13a of the semiconductor laser light source 13 and the reflective film 227, across the optical multiplexing circuit 215 having a wavelength selecting function therebetween, constitute the optical resonator for oscillating a laser beam having a wavelength lambda _3. The reflection surface 14a and the reflection film 227 of the semiconductor laser light source 14 constitute an optical resonator that oscillates a laser beam having a wavelength of λ ₄ with an optical multiplexing circuit 215 having a wavelength selection function interposed therebetween. . Since the reflection film 227 is common to the optical resonators, the reflection film 2
The light output from the optical fiber 27 to the optical fiber 30 is a light obtained by multiplexing light of wavelengths λ _{1 to} λ ₄ .

In the light source module 2 according to the present embodiment,
The light of each of the wavelengths λ _{1 to} λ ₄ oscillated and output by each optical resonator has a wavelength that can be multiplexed / demultiplexed by the optical multiplexing circuit 215 composed of a Mach-Zehnder interferometer type circuit or an array waveguide diffraction grating type circuit. It is. Light of each wavelength is multiplexed and output from the reflection film 227 shared by each optical resonator. Therefore, the light source module 2 according to the present embodiment can combine with high efficiency and output high output light, and is easy to manufacture.

When the temperature changes, the transmission center wavelength of the optical multiplexing circuit 215 changes, and the oscillation center wavelength of each optical resonator also changes. However, in the present embodiment, the optical multiplexing circuit 215 having the wavelength selection function exists in each resonator, and the reflection film 227 reflects a part of light in a wavelength band including the wavelengths λ _{1 to} λ _4. Since the remaining portion is transmitted, the transmission center wavelength of the optical multiplexing circuit 215 always coincides with the oscillation center wavelength of each optical resonator. Therefore, the optical multiplexing circuit 215 can maintain a favorable multiplexing state without performing special temperature control, and the light source module 2 can stably output high-level light.

The light source module 2 according to the present embodiment
Since the reflection film 227 is integrated on the planar waveguide together with the optical multiplexing circuit 215, the number of components can be reduced, and miniaturization and cost reduction can be achieved. Further, in this embodiment, in particular, only one reflection film 227 is provided as the reflection means, so that the configuration is simplified.

(Third Embodiment) Next, a third embodiment of the light source module according to the present invention will be described. FIG.
FIG. 9 is a configuration diagram of a light source module according to a third embodiment. The light source module 3 according to the present embodiment includes four semiconductor laser light sources 11 to 14 and a four-input one-output optical multiplexer 20.
C. Semiconductor laser light sources 11 to 14
Are the same as those in the first embodiment.

The optical multiplexer 20C has input ports 201 to 2
The input channel waveguides 211 to 214, the optical multiplexing circuit 215, and the output channel waveguide 216 are provided between the output channel 204 and the output port 206, and the chirped grating 226 is provided on the output channel waveguide 216. Have been. This optical multiplexer 20C has an input port 201
To 204, output port 206, input side channel waveguide 2
The output-side channel waveguide 216 on which the optical waveguides 11 to 214, the optical multiplexing circuit 215, and the chirped grating 226 are formed is integrated on a planar waveguide.

The chirped grating 226 is connected to the output channel waveguide 216 via a phase grating mask, for example.
Irradiation of ultraviolet light induces the refractive index modulation, and the refractive index modulation is formed continuously, and the grating interval of the refractive index modulation is continuously changed, and the wavelength of the wavelength according to the grating interval of the refractive index modulation is changed. A part of the light (for example, 5% to 20%) is reflected. The reflection wavelength band of the chirped grating 226 includes a wavelength that can be multiplexed / demultiplexed by the optical multiplexing circuit 215.
Therefore, the chirped grating 226 transfers a part of the light output from the output end 256 of the optical multiplexing circuit 215 and guided through the output-side channel waveguide 216 to the output end 25.
6 and the remainder is transmitted toward output port 206.

The optical multiplexing circuit 215 has an input terminal 251.
But in which outputs light having a wavelength lambda ₁ to [lambda] ₄ entered in ～254 multiplexed to the output terminal 256, when light at the output end 256 in the opposite to the input, and demultiplexes the light, the wavelength lambda ₁ light is the first
, The light of wavelength λ ₂ is output to the second input terminal 252, the light of wavelength λ ₃ is output to the third input terminal 253, and the light of wavelength λ ₄ is output to the _fourth input terminal 253. Is output to the input terminal 254.

That is, in this embodiment, the reflecting surface 11a of the semiconductor laser light source 11 and the chirped grating 2
26 is an optical multiplexing circuit 2 having a wavelength selecting function between the two.
An optical resonator that oscillates a laser beam having a wavelength of λ ₁ is formed with 15 interposed therebetween. Reflection surface 12a of semiconductor laser light source 12
And a chirped grating 226, with an optical multiplexing circuit 215 having a wavelength selecting function interposed therebetween, and a wavelength λ ₂
The optical resonator which oscillates the laser light of the above. The reflective surface 13a and the chirped grating 226 of the semiconductor laser light source 13, across the optical multiplexing circuit 215 having a wavelength selecting function therebetween, constitute the optical resonator for oscillating a laser beam having a wavelength lambda _3. The reflection surface 14a of the semiconductor laser light source 14 and the chirped grating 226
Across the optical multiplexing circuit 215 having a wavelength selecting function therebetween, constitute the optical resonator for oscillating a laser beam having a wavelength lambda _4. Since the chirped grating 226 is common to the optical resonators, the light output from the chirped grating 226 toward the output port 206 is a light obtained by multiplexing the light of wavelengths λ _{1 to} λ _4. It is.

In the light source module 3 according to the present embodiment,
The light of each of the wavelengths λ _{1 to} λ ₄ oscillated and output by each optical resonator has a wavelength that can be multiplexed / demultiplexed by the optical multiplexing circuit 215 composed of a Mach-Zehnder interferometer type circuit or an array waveguide diffraction grating type circuit. It is. Light of each wavelength is multiplexed and output from the chirped grating 226 shared by each optical resonator. Therefore, the light source module 3 according to the present embodiment can combine light with high efficiency and output high output light, and is easy to manufacture.

When the temperature changes, the transmission center wavelength of the optical multiplexing circuit 215 changes, and the oscillation center wavelength of each optical resonator also changes. However, in the present embodiment, the optical multiplexing circuit 215 having the wavelength selection function exists in each resonator, and the chirped grating 226 reflects a part of the light in the wavelength band including the wavelengths λ _{1 to} λ _4. Since the remaining portion is transmitted, the transmission center wavelength of the optical multiplexing circuit 215 always coincides with the oscillation center wavelength of each optical resonator. Therefore, the optical multiplexing circuit 215 can maintain a favorable multiplexing state without performing special temperature control,
The light source module 3 can stably output high-level light.

The light source module 3 according to the present embodiment
Means that the chirped grating 226 is
5 and integrated on a planar waveguide, the number of components can be reduced, and miniaturization and cost reduction can be achieved. In addition, in the present embodiment, in particular, only one chirped grating 226 is provided as the reflection means, so that the configuration is simplified.

The optical multiplexer 20C includes an optical multiplexer 21
5 and the chirped grating 226 are integrated on a planar waveguide, but as shown in FIG. 6, a chirped grating element 226 is provided separately from the planar waveguide in which the optical multiplexing circuit 215 is integrated. You may.

(Fourth Embodiment) Next, an embodiment of the light source unit according to the present invention will be described. FIG.
It is a lineblock diagram of a light source unit concerning an embodiment. The light source unit 6 according to the present embodiment includes light source modules 4 and 5, polarization maintaining optical fibers 31 and 32, and a polarization combiner 33.

Each of the light source modules 4 and 5 is one of the light source modules 1 to 3 described above and has a wavelength λ ₁
Λ ₄ are combined and output from the output port 206.
In particular, in the present embodiment, the output port 2 of the light source module 4
It is assumed that the lights of wavelengths λ _{1 to} λ ₄ multiplexed from 06 and output are polarized in a certain direction. Similarly, it is assumed that the lights of wavelengths λ _{1 to} λ ₄ multiplexed and output from the output port 206 of the light source module 5 are also polarized in a certain direction.

The polarization-maintaining optical fiber 31 receives the light of wavelengths λ _{1 to} λ ₄ polarized in a fixed direction output from the output port 206 of the light source module 4, and maintains the polarization state while maintaining the polarization state. The light is guided to the wave synthesizer 33. Similarly, the polarization maintaining optical fiber 32 has wavelengths λ _{1 to} λ _4, which are output from the output port 206 of the light source module 5 and are polarized in a certain direction.
And guided to the polarization combiner 33 while maintaining its polarization state. Then, the polarization combiner 33 performs polarization combination of the light arriving via the polarization-maintaining optical fibers 31 and 32, and outputs the polarization-combined light to the optical fiber 34.

The light source unit 6 according to the present embodiment has the same effects as those of the light source modules 1 to 3 described above, and also has the following effects. That is, in the present embodiment, the light output from each of the two sets of light source modules 4 and 5 is polarized and combined by the polarization combiner 33 and output, so that the light source unit 6 It is possible to output light at a higher level than the output light level.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, the number of semiconductor laser light sources included in the light source module is four in the above embodiment, but may be larger. In particular, when the optical multiplexing circuit 215 is an arrayed waveguide grating type circuit, it is possible to provide more semiconductor laser light sources and multiplex light having a larger wave number.

[0047]

As described above in detail, according to the light source module of the present invention, the light source module comprises a reflecting means (chirped grating, reflecting member) and a reflecting surface of each light emitting element (semiconductor laser light source). Laser oscillation occurs in each optical resonator, and light of a predetermined wavelength is obtained. Light of each wavelength obtained by each optical resonator is multiplexed by an optical multiplexing circuit (Mach-Zehnder interferometer type circuit, array waveguide diffraction grating type circuit), and the multiplexed light is output from an output port. . Since the oscillation center wavelength in each optical resonator matches the transmission center wavelength of the optical multiplexing circuit provided in the optical resonator and having a wavelength selection function, even if the temperature fluctuates,
A high level of light output is always obtained stably, and manufacturing is easy. In addition, since only one reflecting means needs to be provided, the number of parts is small, and miniaturization and cost reduction can be achieved.

According to the light source unit of the present invention, the light output from the output port of each of the two sets of light source modules is obtained by multiplexing light of multiple wavelengths and is polarized in a certain direction. While the state of polarization is maintained, the signal is input to the polarization combiner, and the polarization is combined and output by the polarization combiner. Therefore, this light source unit can stably output light at a level higher than the level of light output from a single light source module regardless of temperature fluctuations.

As described above, each of the light source module and the light source unit according to the present invention can stably output high-level light regardless of temperature fluctuation. It is suitably used as an excitation light source in the above.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a light source module according to a first embodiment.

FIG. 2 is a configuration diagram of a light source module according to a second embodiment.

FIG. 3 is a diagram illustrating a circuit example of an optical multiplexing circuit.

FIG. 4 is a diagram illustrating a circuit example of an optical multiplexing circuit.

FIG. 5 is a configuration diagram of a light source module according to a third embodiment.

FIG. 6 is a diagram illustrating another configuration of the light source module according to the third embodiment.

FIG. 7 is a configuration diagram of a light source unit according to a fourth embodiment.

[Explanation of symbols]

1-5: Light source module, 6: Light source unit, 11-1
4 ... Semiconductor laser light source, 20A-20C ... Optical multiplexer, 3
0: optical fiber, 31, 32: polarization maintaining optical fiber, 3
3: polarization combiner, 34: optical fiber, 201-204 ...
Input port, 206: output port, 211 to 214: input side channel waveguide, 215: optical multiplexing circuit, 216 ... output side channel waveguide, 226 ... chirped grating, 227 ... reflection film.

Claims (7)

[Claims] An optical multiplexing circuit for multiplexing lights having different wavelengths input to a plurality of input ports, respectively; and a multiplexed light in a wavelength band including each wavelength of the light multiplexed by the optical multiplexing circuit. Reflecting means for reflecting a part of the emitted light and transmitting the remainder to the output port, a reflecting surface and an output surface, and inputting and outputting light between the output surface and each of the plurality of input ports. A light source module comprising: a plurality of light emitting elements each including a reflection surface and the reflection unit forming an optical resonator. 2. The light source module according to claim 1, wherein the optical multiplexing circuit is a Mach-Zehnder interferometer type circuit. 3. The light source module according to claim 1, wherein said optical multiplexing circuit is an arrayed waveguide diffraction grating type circuit. 4. The light source module according to claim 1, wherein said reflection means is a reflection member provided between said optical multiplexing circuit and said output port or at said output port. 5. The light source module according to claim 1, wherein said reflection means is a chirped grating provided between said optical multiplexing circuit and said output port. 6. The light source module according to claim 1, wherein said optical multiplexing circuit and said reflection means are integrated on a planar waveguide. 7. Two types of light source modules according to claim 1 of a polarization maintaining type, and two types of light output from the output ports of the respective light source modules are input, A light source unit comprising: a polarization combiner that combines these lights with polarization and outputs the combined light.