JP2010034114A - Laser device, laser module, and wavelength multiplexing optical communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance exterior resonator type wavelength-variable laser device which suppresses problems of coupling loss between optical components and a bulky size occurring when a modulator is connected, and can modulate an optical signal stably. <P>SOLUTION: The wavelength-variable laser 20 includes an exterior resonator 19 and a semiconductor element 18 with one end adjacent to the exterior resonator 19 and other end a laser light emission end part. The semiconductor element 18 includes a phase regulating region 17 provided on one end side, a gain region 16 provided on a laser light emission end part side of the phase regulating region 17, a wideband reflection mirror 15 provided on a laser light emission end part side of the gain region 16, and an EA modulation region 14 provided on a laser light emission end part side of the wideband reflection mirror 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser device, a laser module, and a wavelength division multiplexing optical communication system.

  The wavelength division multiplexing (WDM) optical communication technology is a technology that has various application possibilities, such as enabling high-capacity and high-speed transmission in a trunk line system and providing a wavelength routing function in an access system. In this WDM optical communication, it is necessary to prepare a semiconductor laser module having a large number of oscillation wavelengths that matches a channel wavelength grid specified by the system side.

  Conventionally, since the oscillation wavelength of the semiconductor laser module is fixed to a single wavelength, it is necessary to prepare modules for the number of wavelengths, and there has been a problem of complicated inventory management.

  Therefore, as a method of changing the oscillation wavelength with a single module, a distributed feedback (Distributed Feed-Back: DFB) type laser array, a sampled grating-distributed Bragg reflection (Sampled Bragg Reflector: SG-DBR) type laser, Alternatively, an external resonator type laser as shown in Non-Patent Document 1 has been devised.

J. De Merlier et al, "Full C-Band External Cavity Wavelength Tunable Laser Using a Liquid-Crystal-Based Tunable Mirror" IEEE PHOTONICS TECHNOLOGY LETTERS, VOL.17, No.3, pp681-683, March 2005

  However, when using a conventional external resonator type wavelength tunable laser module in an optical communication system, it is necessary to connect the modulator to the laser device (for the detailed configuration, the invention of this document is implemented). (This will be described in the best mode for achieving this).) There are problems such as an increase in coupling loss at the junction and a large module size.

  The present invention has been made to solve the above-described problems, and suppresses the problem of bulky coupling loss and size between optical components caused by connecting a modulator, thereby stably modulating an optical signal. It is an object of the present invention to provide a high-performance external resonator type wavelength tunable laser device capable of performing

  A laser apparatus according to the present invention includes an external resonator, a semiconductor element having one end adjacent to the external resonator and having the other end as a laser beam emitting end, and the semiconductor element is provided in a phase adjustment region provided on one end side. , A gain region provided on the laser beam emission end side of the phase adjustment region, a broadband reflection mirror provided on the laser beam emission end side of the gain region, and a modulation provided on the laser beam emission end side of the broadband reflection mirror Configured with areas.

  Since the semiconductor element included in the laser device of the present invention includes the broadband reflection mirror between the laser light emitting end and the gain region, the reflection position of the resonator is defined. As described above, since the resonator end face is defined in the semiconductor element, the modulation region can be integrated in the semiconductor element. In addition, since the modulation area is integrated in the laser device of the present invention, the size of the laser module including the laser device can be reduced.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

<Embodiment 1>
(Constitution)
FIG. 1 is a cross-sectional view showing a basic configuration of a wavelength tunable laser (laser device) 20 according to the first embodiment. The wavelength tunable laser 20 includes an external resonator 19 and a semiconductor element 18 that is adjacent to the external resonator 19 at one end and has the other end as a laser light emitting end. The semiconductor element 18 is provided on the phase adjustment region 17 provided on one end side, the gain region 16 provided on the laser beam emission end side of the phase adjustment region 17, and the laser beam emission end side of the gain region 16. The broadband reflection mirror 15 and an electroabsorption (EA) modulator (modulation region) 14 provided on the laser beam emission end side of the broadband reflection mirror 15 are integrated. The low reflection film 1a is formed on the emission end face side, that is, the other end side, and the low reflection film 1b is also formed on the opposite side, that is, one end side.

  The external resonator 19 includes a lens (condensing lens) 11, an etalon (etalon filter) 12, and a liquid crystal wavelength tunable mirror 13 which are sequentially arranged from one end side of the semiconductor element.

  As shown in FIG. 1, the EA modulator 14 has a structure in which the multiple quantum well absorption layer 4 is sandwiched between the p-InP lower cladding layer 8a and the n-InP upper cladding layer 3a on the p-InP substrate 9. An n-side electrode 2a is formed on the n-InP upper cladding layer 3a. The broadband reflecting mirror 15 has a structure in which the chirped diffraction grating 5 is sandwiched between the p-InP lower cladding layer 8b and the n-InP upper cladding layer 3b. The gain region 16 has a structure in which a p-InP lower cladding layer 8c, an active layer 6, and an n-InP upper cladding layer 3c are stacked on a p-InP substrate 9, and an n-side electrode 2b is formed thereon. Yes. Similarly, the phase adjustment region 17 has a structure in which a p-InP lower cladding layer 8d, an active layer 7, and an n-InP upper cladding layer 3d are laminated on a p-InP substrate 9, and an n-side electrode is formed thereon. 2c is formed. Each region described above is formed on the p-InP substrate 9, and the p-side electrode 10 is formed under the p-InP substrate 9.

  Here, FIG. 2 shows the reflection spectrum 22 of the liquid crystal wavelength tunable mirror 13, the transmission spectrum 23 and free spectrum range 24 of the etalon 12, the resonator mode 25, and the reflection spectrum 26 of the broadband reflection mirror 15 with the horizontal axis as the wavelength. FIG.

  The reflection spectrum 26 of the wide-band reflecting mirror 15 desirably has a substantially flat characteristic as shown in FIG. 2 over the entire C band (1530 to 1565 nm) of an ITU (International Telecommunication Union) grid. The bandwidth obtained is approximately 35 nm.

  When the reflectance of the broadband reflecting mirror 15 is low, the gain of resonance generated with the liquid crystal wavelength tunable mirror 13 is lowered and the threshold voltage is increased. Therefore, the reflectance of the broadband reflecting mirror 15 is at least 10% or more. It is desirable that

  As a means for realizing the broadband reflection mirror 15 as described above, a configuration having the chirped diffraction grating 5 is conceivable. Here, the chirped diffraction grating is a kind of diffraction grating having a perturbation in the repetition period of the diffraction grating.

(Operation)
Next, the operation of the wavelength tunable laser 20 will be described with reference to FIGS. A laser beam is generated in the active layer 6 by flowing a current in the forward direction between the n-side electrode 2 b and the p-side electrode 10 in the gain region 16 and injecting a current into the active layer 6. Since the active layer 6 is a multi-quantum well layer made of InGaAsP, the generated laser light is almost confined and propagated in the active layer 6 having a higher refractive index than the surrounding cladding layer made of InP. The laser beam propagating in this way resonates between the broadband reflection mirror 15 and the liquid crystal wavelength tunable mirror 13 and oscillates when the gain exceeds the loss. Since the resonator length is several millimeters, a very large number of resonator modes exist in this configuration, and the oscillation wavelength is not fixed to a single one. However, as shown in FIG. 2, the transmission peak in the transmission spectrum 23 of the etalon 12 The liquid crystal wavelength tunable mirror 13 oscillates at a wavelength at which the reflection peak 22a in the reflection spectrum 22 overlaps.

  The liquid crystal wavelength tunable mirror 13 can change the wavelength of the reflection peak 22a of the reflection spectrum by changing the refractive index of the liquid crystal according to the voltage applied to the liquid crystal.

  As described above, since the reflection peak 22a of the liquid crystal wavelength tunable mirror 13 can be changed, the transmission peak of the etalon 12 is designed according to the ITU grid, which is the standard for optical communication light sources, and is determined by the standard. Each wavelength can be oscillated. At this time, in order to make the transmission peak of the etalon 12 coincide with the wavelength of the resonator mode 25, the equivalent refractive index of the phase adjustment region 17 is decreased by passing a current between the n-side electrode 2 c and the p-side electrode 10. Thus, the position of the resonator mode 25 can be finely adjusted.

  As described above, the wavelength variable operation is realized by controlling the voltage applied to the liquid crystal wavelength variable mirror 13 and adjusting the amount of current flowing to the phase adjustment region 17. As described above, the wavelength tunable operation can be realized with only two parameters, so that the wavelength control is easy.

(effect)
FIG. 3 is a cross-sectional view showing a basic configuration of a conventional wavelength tunable laser 20 described in Non-Patent Document 1. As shown in FIG. When the conventional wavelength tunable laser 20 is used in an optical communication system, it is necessary to connect a modulator (not shown) separately from the semiconductor element 18 and the external resonator 19 shown in the figure. There was a problem of increase in size and size.

  FIG. 4 is a comparative example of the first embodiment, which is a semiconductor laser in which the EA modulator 14 is integrated by a butt joint with respect to the wavelength tunable laser 20 shown in FIG. Since there is no broadband reflection mirror 15 as shown in FIG. 4, there is no reflection end between the EA modulator 14 and the gain region 16 to form a resonator paired with the end face of the external resonator, Laser oscillation cannot be reached.

  FIG. 5 shows another comparative example with respect to the first embodiment, which is a semiconductor laser having a structure in which a gap mirror 27 formed by dry etching is sandwiched between the gain region 16 and the EA modulator 14. In this case, the laser oscillation is possible because the end face on the side of the gain region 16 in the gap position acts as the end of the resonator, but the laser beam is reflected and returned by the end face on the EA modulator 14 side of the gap mirror 27. The noise caused by can not be prevented.

  On the other hand, in the case of the present embodiment, since the broadband reflection mirror 15 having a chirped diffraction grating structure is provided as described above, a wide range of wavelengths of laser light are reflected at different diffraction grating positions, and a large number of resonances occur. The container mode will stand. Among these many modes, laser oscillation is possible at a wavelength where the transmission peak of the etalon 12 and the reflection peak of the liquid crystal wavelength tunable mirror 13 overlap each other, and reflection at the interface between the EA modulator 14 and the broadband reflection mirror 15 is very high. Since it can be designed to be small, it is possible to prevent the influence of noise due to return light.

  Next, the operation of the EA modulator 14 in the first embodiment will be described. The EA modulator 14 has a configuration in which a multiple quantum well (MQW) absorption layer 4 is sandwiched between a p-InP lower cladding 8a and an n-InP upper cladding 3a. When a reverse bias is applied perpendicularly to the MQW absorption layer 4, a significant shift of the absorption edge occurs due to the quantum confined stark effect (QCSE), so that the intensity of the laser light transmitted through the broadband reflection mirror 15 is modulated. It is possible to superimpose signals.

  In FIG. 1, the EA modulator 14 is shown as an integrated modulator, but any system may be used as long as it is a modulator formed by a semiconductor process. For example, a Mach-Zehnder (MZ) modulator can be integrated.

<Embodiment 2>
(Constitution)
FIG. 6 is a cross-sectional view showing a basic configuration of the wavelength tunable laser 20 in the second embodiment. In addition to the configuration of the first embodiment, the wavelength tunable laser 20 of the second embodiment further includes a semiconductor amplifier (SOA) 29 provided on the laser beam emission end side of the EA modulator 14. . The SOA 29 has a configuration in which an active layer 28 having a refractive index higher than that of the cladding layer is sandwiched between the p-InP lower cladding 8e and the n-InP upper cladding 3e. An n-side electrode 2d is formed on the n-InP upper cladding layer 3e. The region of the SOA 29 described above is formed on the p-InP substrate 9, and the p-side electrode 10 is formed under the p-InP substrate 9.

  Since the other configuration is the same as that of the wavelength tunable laser 20 shown in FIG. 1 in the first embodiment, a detailed description thereof is omitted here.

(Operation)
In the wavelength tunable laser 20 shown in FIG. 6, the laser light output emitted from the SOA 29 is adjusted by adjusting the voltage between the n-side electrode 2 d and the p-side electrode 10. Since other operations are the same as those of the wavelength tunable laser 20 shown in FIG. 1 in the first embodiment, a detailed description thereof is omitted here.

(effect)
By forming the SOA 29, the output of the emitted laser beam can be adjusted. In addition, if a window region having a refractive index smaller than that of the active layer 28 is formed on the laser light emitting end face side of the SOA 29, the resistance to the reflected return light can be increased. Further, instead of forming the window region, the same effect can be obtained by bending the waveguide on the laser light emitting end face side so that the wavefront of the light propagating through the active layer 28 does not intersect the laser light emitting end face. .

  In FIG. 5, the SOA 29 is integrated in the subsequent stage of the EA modulator 14. However, even if the SOA 29 is integrated between the EA modulator 14 and the broadband reflection mirror 15, the same effect is obtained.

<Embodiment 3>
(Constitution)
FIG. 7 is a schematic diagram showing a basic configuration of an external resonator type wavelength tunable laser module (laser module) 39 according to the third embodiment. The external resonator type wavelength tunable laser module 39 includes a wavelength tunable laser 20, and a lens 32 and a ferrule 31 are sequentially arranged from the laser beam emitting end side of the wavelength tunable laser 20. The A wiring 34 for applying a voltage to the electrode is connected to the semiconductor element 18 constituting the wavelength tunable laser 20, and a wiring 35 for adjusting the voltage is also connected to the liquid crystal wavelength tunable mirror 13.

  Further, a hole for passing the ferrule 31 and the wirings 34 and 35 to the outside is formed, and a package 33 is provided so as to cover the whole. That is, the wavelength tunable laser 20 including the semiconductor laser 18, the lens 11, the etalon 12, and the liquid crystal wavelength tunable mirror 13 is housed in the package 33 together with the condensing lens 32 and the ferrule 31, the optical fiber 30, and other wirings 34 and 35. It has been.

  Since the configuration of the wavelength tunable laser 20 is the same as that shown in FIG. 1 in the first embodiment, a detailed description thereof is omitted here.

(Operation)
Next, the operation of the external resonator type tunable laser module 39 shown in FIG. 7 will be described. First, an electrical signal is input between the electrodes of the semiconductor element 18 through the wiring 34 drawn out of the package 33. The generated laser light is emitted to the external resonator, and only light having a wavelength corresponding to the voltage applied through the wiring 35 is reflected by the liquid crystal wavelength tunable mirror 13, and laser oscillation occurs when the gain exceeds the loss.

  The laser-oscillated light is intensity-modulated according to a voltage signal applied to the EA modulator 14 integrated in the semiconductor element 18, and a laser beam 21 is emitted. The emitted laser light 21 is condensed by the lens 32 onto the optical fiber 30 fixed to the ferrule 31. This makes it possible to modulate and transmit an optical signal having an arbitrary wavelength in the ITU grid.

(effect)
FIG. 8 is a schematic diagram showing a configuration of an external resonator type tunable laser module 39 which is a conventional modulator hybrid integrated type, which is cited as a comparative example of the third embodiment. The difference from the present embodiment is that no modulator is integrated in the semiconductor element 18, so that the laser beam 21 is optically integrated into the EA modulator 36 via the lens 32 after being emitted and passed through the lens 37. It is in a position where it is focused onto an optical fiber. With the above configuration, the driving of the EA modulator 36 is realized by applying a reverse bias to the wiring 38.

  As described above, since the EA modulator 36 is optically coupled, the optical axis adjustment during the manufacturing process becomes more complicated, which causes an increase in cost. Further, there is a demerit such that the size of the package 33 needs to be increased.

  FIG. 9 is a schematic diagram showing a configuration of a conventional external resonator type tunable laser module 39 given as another comparative example of the third embodiment. Unlike FIG. 8 configured as a single module by hybrid integration, the modulator module 43 and the wavelength tunable laser module 44 are individually arranged, and both are connected by an optical fiber 30a. As in the above configuration, the EA modulator 41 is driven by applying a reverse bias to the wiring 42.

  Since the modulator module 43 and the wavelength tunable laser module 44 are used instead of a single module, there is a problem that a coupling loss occurs in the optical fiber 30a responsible for coupling between the two. In addition, there is a demerit that a package is required for each module and the overall configuration is bulky.

  On the other hand, in the case of the third embodiment, since the EA modulator 36 is formed in the semiconductor element 18, the semiconductor element 18 as in the external resonator type wavelength tunable laser module 39 shown in FIG. 8 or FIG. 9. Since it is not necessary to prepare the EA modulators 36 and 41 installed separately, it is possible to suppress an increase in cost, an increase in package size, and an optical coupling loss.

<Embodiment 4>
(Constitution)
FIG. 10 is a schematic diagram showing a basic configuration of the external resonator type wavelength tunable laser module 39 according to the fourth embodiment.

  The external resonator type wavelength tunable laser module 39 according to the fourth embodiment includes a beam splitter 45 a between the semiconductor element 18 and the lens 32. Further, a beam splitter 45b that further splits a laser beam split by the beam splitter 45a and emitted in a direction different from the lens 32, and a first laser beam that receives and detects the laser output of the wavelength tunable laser 20 split by the beam splitter 45b. A photodiode (first photodetector) 46 is provided.

  A second photodiode (second light) that receives the laser beam reflected by the mirror 49 is provided, which includes a mirror 49 that reflects the laser beam that is split by the beam splitter 45b and is emitted in a direction different from the first photodiode 46. Detector) 50. An etalon (second etalon filter) 47 is installed between the beam splitter 45 b and the mirror 49. That is, the second photodiode 50 receives and detects the laser output of the wavelength tunable laser 20 via the etalon 47.

  A temperature sensor (temperature monitor) 48 adjacent to the etalon 47 is further provided. Although not shown, an external control circuit for calculating a drift amount from a desired ITU-T grid wavelength and adjusting a voltage applied to the phase adjustment region 17 in the semiconductor element 18 is provided. The external control circuit includes a wavelength drift detection mechanism that detects a wavelength drift of the laser output based on a detection result of the first photodiode 46 and a detection result of the second photodiode 50, and a wavelength drift compensation mechanism that compensates for the wavelength drift. With.

  Since other configurations are the same as those in FIG. 7 described in the third embodiment, a detailed description thereof is omitted here. Therefore, the external resonator type wavelength tunable laser module 39 according to the fourth embodiment includes, in addition to the configuration of the third embodiment, the beam splitters 45a and 45b, the first photodiode 46, the second photodiode 50, and the etalon. 47, a wavelength locker 70 comprising a temperature sensor 48 is disposed, and a system for performing feedback control according to the output and wavelength of the monitored light is provided.

(Operation)
Next, the operation of the external resonator type tunable laser module 39 according to the present embodiment will be described. A part of the laser light 21 emitted by the same procedure as in the third embodiment is guided to the wavelength locker 70 by the beam splitter 45a. The laser beam guided to the wavelength locker 70 is further branched by the beam splitter 45b. One is led to the second photodiode 50 through the etalon 47 and the mirror 49, and the other is led to the first photodiode 46.

  Next, the operation of the wavelength locker 70 according to the present embodiment will be described. FIG. 11 is a schematic diagram showing a part of the transmittance spectrum of the etalon 47. The etalon 47 is designed so that the desired ITU-T grid wavelength 51 comes in the slope of the transmittance spectrum. If the laser oscillation wavelength is constant, the ratio between the output of the first photodiode 46 and the output of the second photodiode 50 has a constant value proportional to the transmittance of the etalon 47. Therefore, when the laser beam output changes, the outputs of the two photodiodes change simultaneously while maintaining the ratio. On the other hand, when the oscillation wavelength of the laser beam 21 changes, the output of the first photodiode 46 does not change, and only the output of the second photodiode 50 changes. That is, the output ratio of the photodiode changes, and the transmittance of the etalon 47 is shifted from the rated etalon transmittance 55. In this way, the wavelength drift 52 is detected by examining the deviation between the photodiode output ratio and the etalon transmittance.

  As described above, the change in the photodiode output ratio correlates with the increase or decrease in the etalon transmittance. Taking the case of FIG. 8 as an example, the increase in the output ratio, that is, the increase in the etalon transmittance is on the short wavelength side. The wavelength drift to one oscillation wavelength 53 is shown. On the contrary, a decrease in the output ratio, that is, a decrease in the etalon transmittance indicates a wavelength drift to the second oscillation wavelength 54 on the long wavelength side.

  The oscillation wavelength of the laser light 21 estimated from the correlation between the etalon transmittance spectrum and the photodiode output ratio and the drift amount of the desired ITU-T grid wavelength 51 are calculated, and the phase adjustment region 17 is connected via an external control circuit (not shown). The drift of the oscillation wavelength is compensated by adjusting the voltage applied to.

  Further, since the transmittance of the etalon 47 is temperature dependent, an external control circuit (not shown) determines whether the change in the photodiode output ratio is due to the drift of the laser light oscillation wavelength or the temperature change in the etalon transmittance. For this purpose, the temperature of the etalon 47 is detected by the temperature sensor 48 to compensate for the temperature dependence of the transmittance spectrum. That is, the wavelength drift detection mechanism included in the external control circuit detects the wavelength drift of the laser output based on the detection result of the temperature sensor 48.

(effect)
Since the external resonator type wavelength tunable laser module 39 according to the present embodiment includes the wavelength locker 70 described above, it is possible to compensate for the drift of the oscillation wavelength.

  Instead of using the temperature sensor 48, a temperature control element (Thermo-Electric Cooler: TEC) is disposed on the bottom surface of the package in the fourth embodiment, and the temperature dependence of the component parts is controlled to be constant. This compensation may be excluded.

<Embodiment 5>
(Constitution)
FIG. 12 is a schematic diagram showing a basic configuration of a wavelength division multiplexing (WDM) optical communication system 71 in the fifth embodiment. A plurality of modulator-integrated external resonator-type wavelength tunable laser modules 39 (in this embodiment, referred to as modulator-integrated wavelength-tunable laser modules 56) described in the third and fourth embodiments are arranged side by side. It is configured to be connected to the optical multiplexer 58 through the fiber 57. The optical multiplexer 58 is also connected to an optical fiber 59 that outputs the combined light.

  The optical multiplexer 58 includes, for example, an arrayed waveguide grating (AWG) or a fiber Bragg grating (FBG).

(Operation)
Next, the operation of the wavelength division multiplexing optical communication system 71 shown in FIG. 12 will be described. Lasers emitted from the plurality of modulator integrated wavelength tunable laser modules 56 are input to the optical multiplexer 58 via the plurality of optical fibers 57. The optical multiplexer 58 multiplexes the input laser and outputs it to the optical fiber 59.

(effect)
FIG. 13 is a schematic diagram showing a basic configuration of a conventional wavelength division multiplexing optical communication system 71 shown as a comparative example of the fifth embodiment. The difference from the fifth embodiment is that the wavelength tunable laser module 60 and the modulator module 61 exist separately and are connected by an optical fiber 62 therebetween. The wavelength tunable laser module 60 is configured by the wavelength tunable laser 20 as shown in FIG. That is, the EA modulators 14 and 36 are not included.

  In the conventional configuration as shown in FIG. 13, there is an extra coupling loss at the connecting portion by the optical fiber 62, whereas in the fifth embodiment, the modulator is integrated in the modulator integrated wavelength tunable laser module 56. Therefore, it is possible to provide a high-quality wavelength tunable light source with little coupling loss.

It is sectional drawing which shows the structure of the wavelength variable laser of this Embodiment 1. FIG. FIG. 3 is a schematic diagram illustrating an operation principle of the wavelength tunable laser according to the first embodiment. It is sectional drawing which shows the structure of the conventional external resonator type | mold tunable laser. It is sectional drawing which shows the structure of the semiconductor laser which is a comparative example of this Embodiment 1. FIG. FIG. 6 is a cross-sectional view showing a configuration of a semiconductor laser that is another comparative example of the first embodiment. It is sectional drawing which shows the structure of the wavelength variable laser of this Embodiment 2. It is the schematic which shows the structure of the laser module of this Embodiment 3. It is the schematic which shows the structure of the conventional wavelength tunable laser module. It is the schematic which shows another structure of the conventional wavelength tunable laser module. It is the schematic which shows the structure of the laser module of this Embodiment 4. It is a schematic diagram explaining the principle of the wavelength locker used in the laser module of this Embodiment 4. FIG. 10 is a schematic diagram illustrating a configuration of a wavelength division multiplexing optical communication system according to a fifth embodiment. It is the schematic which shows the structure of the conventional wavelength division multiplexing optical communication system which is a comparative example of this Embodiment 5. FIG.

Explanation of symbols

  1a, 1b Low reflection film, 2a-2d n-side electrode, 3a-3e n-InP upper cladding layer, 4 multiple quantum well (MQW) absorption layer, 5 chirped diffraction grating, 6, 7, 28 active layer, 8a-8e p-InP lower cladding layer, 9 p-InP substrate, 10 p-side electrode, 11, 40 lens, 12,47 etalon, 13 liquid crystal wavelength tunable mirror, 14, 36, 41 EA modulator, 15 broadband reflection mirror, 16 gain Region, 17 phase adjustment region, 18 semiconductor element, 19 external resonator, 20 wavelength tunable laser, 21 laser light, 22 reflection spectrum of liquid crystal wavelength tunable mirror, 22a reflection peak, 23 etalon transmission spectrum, 24 etalon free spectrum range , 25 Cavity mode, 26 Reflection spectrum of broadband reflection mirror, 27 Gap mirror, 29 Semiconductor Amplifier (SOA), 30 optical fiber, 31 ferrule, 32 lens, 33 package, 34, 35, 38, 42 wiring, 37 lens, 39 external resonator type tunable laser module, 43 modulator module, 44 tunable laser module 45a, 45b Beam splitter, 46 First photodiode, 48 Temperature sensor, 49 Mirror, 50 Second photodiode, 51 ITU-T grid wavelength, 52 Wavelength drift, 53, 54 Oscillation wavelength, 55 Rated transmittance, 56 Modulator integrated wavelength tunable laser module, 57, 59, 62 optical fiber, 58 optical multiplexer, 60 wavelength tunable laser module, 61 modulator module, 70 wavelength locker, 71 wavelength multiplexing optical communication system.

Claims (9)

An external resonator,
A semiconductor element adjacent to the external resonator at one end and having the other end as a laser beam emitting end, and
The semiconductor element is
A phase adjustment region provided on the one end side;
A gain region provided on the laser light emitting end side of the phase adjustment region;
A broadband reflection mirror provided on the laser beam emission end side of the gain region;
A modulation region provided on the laser beam output end side of the broadband reflection mirror,
Laser device. The modulation region is an electroabsorption (EA) modulator.
The laser device according to claim 1. The broadband reflecting mirror has a chirped diffraction grating,
The laser device according to claim 1. The external resonator is sequentially disposed from the one end side of the semiconductor element,
A condenser lens;
An etalon filter,
A liquid crystal wavelength tunable mirror,
The laser device according to any one of claims 1 to 3. A semiconductor amplifier (SOA) provided on the laser beam emitting end side of the modulation region;
The laser device according to any one of claims 1 to 4. A laser device according to any one of claims 1 to 5;
Sequentially disposed from the other end side of the laser device,
A lens,
Ferrules,
An optical fiber connected to the ferrule,
Laser module. A first photodetector for detecting a laser output of the laser device;
A second etalon filter;
A second photodetector for detecting the laser output of the laser device via the second etalon filter;
A wavelength drift detection mechanism that detects a wavelength drift of the laser output based on a detection result of the first photodetector and a detection result of the second photodetector;
A wavelength drift compensation mechanism for compensating for the wavelength drift,
The laser module according to claim 6. A temperature monitor adjacent to the second etalon filter;
The wavelength drift detection mechanism detects the wavelength drift of the laser output based also on the detection result of the temperature monitor,
The laser module according to claim 7. A plurality of laser modules according to any one of claims 6 to 8,
An optical multiplexer connected to the plurality of laser modules,
Wavelength multiplexing optical communication system.

Images