JP2011044581A - Semiconductor laser and optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser and an optical module with a high output, a high SN ratio and a broad wavelength variable region. <P>SOLUTION: The semiconductor laser includes DFB lasers 301a-301j which is able to laser-oscillatable of a single-mode laser at different wavelengths, respectively; first connection waveguides 302a-302j; a first optical merging circuit 303 for merging the laser light oscillated from the DFB lasers 301a-301j and propagated in the first connection wageguides 302a-302j; second connection waveguides 308a-308b; a second optical merging circuit 306 for merging laser light propagated in the second connection waveguides 308a-308b with each other; and one output waveguide 307 for outputting the laser light merged at the second optical merging circuit 306. The semiconductor laser can be a wavelength variable light source, by oscillating laser light from a desired DFB laser. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor laser and an optical module which are used in a wavelength division multiplexing optical network and become a wavelength variable light source having a large wavelength variable width.

  As a communication light source, a DFB (Distributed Feedback) laser has been mainly used. However, with the development of a wavelength division multiplexing (WDM) system in recent years, a wavelength variable light source capable of changing an oscillation wavelength is required. It became so. As a wavelength tunable light source for communication, as shown in FIG. 1, a wavelength tunable laser is known which realizes a wide range of wavelength tunability by arraying DFB lasers and combining array selection and temperature tuning based on temperature ( For example, refer nonpatent literature 1).

  FIG. 1 is a diagram showing a structure of a wavelength tunable laser using a DFB array, in which 10 DFB lasers, an S-shaped connection waveguide, an optical multiplexer and an optical amplifier are integrated on an InP substrate. Show. In the figure, 101a to 101j are DFB lasers, 102a to 102j are S-shaped connection waveguides, 103 is an optical converging circuit, 104 is an output waveguide, and 105 is an optical amplifier.

  The operation of the wavelength tunable laser in FIG. 1 is as follows. Ten DFB lasers 101a to 101j are arranged at intervals of 30 microns, and each DFB laser has an individual electrode and operates independently. Each DFB laser has a diffraction grating on its active layer, and is set to oscillate at different wavelengths by setting the pitch of this diffraction grating to a different value for each DFB laser. Since the oscillation wavelength of a DFB laser generally changes by 0.1 nm at a temperature change of 1 ° C., the oscillation wavelength of one DFB laser changes by about 3 nm by changing the temperature of the element by 30 ° C. Therefore, in the case of the wavelength tunable laser shown in FIG. 1, a wide wavelength range of 30 nm or more is covered by combining one of the 10 DFB lasers 101a to 101j and controlling the element temperature. can do.

  Here, the principle of variable oscillation wavelength in the wavelength tunable laser will be described with reference to FIG. FIG. 2 is a diagram for explaining the principle of variable oscillation wavelength in a wavelength tunable laser using a DFB array, and shows the relationship between the oscillation wavelength of each DFB laser and the element temperature. In the figure, 201a to 201j indicate the relationship between the oscillation wavelength of the DFB lasers 101a to 101j and the element temperature. It can be seen from FIG. 2 that each DFB laser changes to the longer wavelength side by about 3 nm in the temperature range of 17 ° C. to 48 ° C. Therefore, it can be seen that the entire wavelength range of the oscillation wavelengths of the ten DFB lasers 101a to 101j covers 30 nm.

  Then, the output light from any of the DFB lasers 101a to 101j enters the optical combining circuit 103 through the S-shaped connection waveguides 102a to 102j. In the optical converging circuit 103, the number of output ports is one with respect to the number of input optical ports of 10, so the light intensity output to the output waveguide 104 is reduced to 1/10. The reduced light intensity is compensated by the semiconductor amplifier 105 and output.

Japanese Patent No. 3237733

H. Oohashi et al., "46.9-nm Wavelength-Selectable Arrayed DFB lasers with Integrated MMI Coupler and SOA", 2001 International Conference on Indium Phosphide and Related Materials Conference Proceedings, 14-18, May 2001, p.575-578 H. Ishii et al., "A Tunable Distributed Amplification DFB Laser Diode (TDA-DFB-LD)", IEEE Photonics Technology Letters, vol. 10, no. 1, January 1998, p.30-32

  A tunable laser with a structure using a DFB laser array and optical converging circuit as shown in FIG. 1 is easy to control and can be fed back to the current value by on-line observation of the wavelength even if the element deteriorates over time. Since it is easy to cope with deterioration, it is an ideal wavelength tunable laser, but has the following problems.

  Multi-mode interferometer (MMI) couplers using multi-mode waveguide interference effects in tunable lasers using a DFB laser array and optical converging circuit, multiple input ports and multiple output ports In the optical combining circuit having n, the number of input optical ports is n (plural), whereas the number of output ports to be used is one, so that the output light intensity is reduced to 1 / n. As a result, the signal-to-noise ratio (SN ratio) of the signal light deteriorates, and even if an optical amplifier compensates for the optical loss, the output light intensity decreases according to the number of arrays, and the SN ratio deteriorates. There was a problem that. Even if the output intensity is compensated by a method such as increasing the length of the optical amplifier, the S / N ratio is not improved, resulting in a problem that the light source is noisy. In addition, since the signal light component that was not output to the output waveguide is emitted from the optical converging circuit in various directions, it is emitted to the front of the device as stray light and offset to the intensity monitor PD (Photo diode) when the module is manufactured. There is a problem that it is difficult to lock the wavelength with high accuracy.

  The present invention has been made in view of the above problems, and an object thereof is to provide a semiconductor laser and an optical module that have a high output and a high SN ratio and a large wavelength variable range.

A semiconductor laser according to a first invention for solving the above-mentioned problems is as follows.
A plurality of waveguide laser cavities each capable of single mode lasing at different wavelengths;
A first connecting waveguide connected to each of the plurality of waveguide-type laser cavities;
A plurality of the first connection waveguides connected to each other, a first optical merging circuit for merging the laser light oscillated from the waveguide type laser cavity and propagated through the first connection waveguide;
At least two second connection waveguides connected to the output side of the first optical converging circuit;
A second optical merging circuit for connecting the at least two second connection waveguides and merging the laser beams respectively propagating through the second connection waveguides;
One output waveguide connected to the output side of the second optical merging circuit and outputting the laser beam merged by the second optical merging circuit;
A wavelength tunable light source is obtained by oscillating laser light from the desired waveguide laser cavity.

A semiconductor laser according to a second invention for solving the above-described problems is as follows.
In the semiconductor laser according to the first invention,
A phase adjustment region for adjusting the phase of the laser light propagating through the second connection waveguide is provided in all the second connection waveguides or in the remaining second connection waveguides except for one. It is provided.

A semiconductor laser according to a third invention for solving the above-mentioned problem is as follows.
In the semiconductor laser according to the first or second invention,
A waveguide type optical amplifier for amplifying the laser light merged by the first optical merging circuit or the second optical merging circuit is provided.

A semiconductor laser according to a fourth invention for solving the above-mentioned problems is as follows.
In the semiconductor laser according to the third aspect,
The waveguide type optical amplifier is provided in each of the second connection waveguides.

A semiconductor laser according to a fifth invention for solving the above-described problem is
In the semiconductor laser according to the third aspect,
The waveguide type optical amplifier is provided in the output waveguide.

A semiconductor laser according to a sixth invention for solving the above-mentioned problem is as follows.
In the semiconductor laser according to any one of the first to fifth inventions,
The first optical merging circuit is a multimode interference coupler or a funnel coupler.

A semiconductor laser according to a seventh invention for solving the above-mentioned problems is as follows.
In the semiconductor laser according to any one of the first to sixth inventions,
The second optical merging circuit is any of a multimode interference coupler, a directional coupler, and a Y-shaped optical merging device.

A semiconductor laser according to an eighth invention for solving the above-mentioned problems is as follows.
In the semiconductor laser according to any one of the first to seventh inventions,
An optical modulator that modulates at least one of the intensity and phase of laser light is provided on the output side of the second optical converging circuit.

A semiconductor laser according to a ninth invention for solving the above-mentioned problems is as follows.
In the semiconductor laser according to the eighth invention,
The optical modulator is an electroabsorption modulator or a Mach-Zehnder modulator.

A semiconductor laser according to a tenth invention for solving the above-mentioned problems is
In the semiconductor laser according to any one of the first to seventh inventions,
Adjust the phase difference between the laser beams propagating through the second connection waveguide to all the second connection waveguides, or to the remaining second connection waveguide except for one, An optical phase modulator for modulating the light intensity is provided.

A semiconductor laser according to an eleventh invention for solving the above-mentioned problems is
In the semiconductor laser according to any one of the first to tenth inventions,
At least one of the waveguide laser cavity and the optical modulator is processed into a stripe structure, and both sides of the stripe structure are embedded with a semi-insulating semiconductor crystal doped with ruthenium.

An optical module according to a twelfth invention for solving the above-mentioned problems is
The semiconductor laser according to any one of the first to eleventh inventions;
A first lens that converts light emitted from the semiconductor laser into parallel rays;
A second lens for condensing the light as parallel rays;
An isolator disposed between the first lens and the second lens to prevent reflection of the light to the semiconductor laser;
The condensed light is coupled to an optical fiber and output.

An optical module according to a thirteenth aspect of the present invention for solving the above problem is
In the optical module according to the twelfth invention,
Furthermore, it has a wavelength locker for controlling the wavelength and power of light emitted from the semiconductor laser.

  According to the first to eleventh aspects of the present invention, the laser beams propagated through the second connection waveguides are merged with each other by the second optical merge circuit in which the two second connection waveguides are connected. It is possible to reduce the optical loss due to the first optical merging circuit, enable high output operation, suppress stray light, and realize a wavelength variable light source having a high S / N ratio. As a result, it is possible to provide a semiconductor laser having a high output and a high SN ratio and a large wavelength variable range.

  According to the twelfth aspect of the present invention, it is possible to realize a variable wavelength light source with a modulation function capable of high output operation and having a high SN ratio.

  According to the thirteenth invention, it is possible to realize a wavelength tunable light source with a modulation function having a high S / N ratio and capable of high output operation with high accuracy of absolute wavelength and high wavelength stability.

It is a structural diagram of a conventional wavelength tunable laser. It is a figure which shows the wavelength tuning characteristic of the conventional wavelength tunable laser. 1 is a structural diagram of a wavelength tunable laser showing Example 1 of the present invention. FIG. 6 is a structural diagram of a wavelength tunable laser showing Example 2 of the present invention. FIG. 6 is a structural diagram of a wavelength tunable laser showing Example 3 of the present invention. It is a figure which shows the input / output characteristic of an optical amplifier. FIG. 6 is a structural diagram of a wavelength tunable laser showing Example 4 of the present invention. FIG. 6 is a structural diagram of a wavelength tunable laser showing Example 5 of the present invention. FIG. 6 is a structural diagram of a wavelength tunable laser showing Example 6 of the present invention. FIG. 9 is a structural diagram of a wavelength tunable laser showing Example 7 of the present invention. It is sectional drawing of the wavelength-tunable laser of the stripe structure which shows Example 8 of this invention. It is sectional drawing of the optical module which shows Example 9 of this invention.

  Hereinafter, some embodiments of the semiconductor laser and the optical module according to the present invention will be described with reference to FIGS.

Example 1
FIG. 3 is a diagram showing a wavelength tunable laser according to the present embodiment. A tunable laser using a DFB array in which a DFB laser is used as a waveguide laser cavity capable of oscillating a single mode and a plurality of these are aligned. The structure is shown. In the drawing, 301a to 301j are DFB lasers, 302a to 302j are first connection waveguides, 303 is a first optical converging circuit, 304a and 304b are second connection waveguides, 305 is an optical amplifier, and 306 is a second connection waveguide. An optical converging circuit, 307 indicates an output waveguide, and 308a and 308b indicate phase adjustment regions, respectively.

  The DFB lasers 301 a to 301 j are respectively connected to the first connection waveguides 302 a to 302 j, and the first connection waveguides 302 a to 302 j are connected to the first optical merge circuit 303. At least two second connection waveguides 304a and 304b are connected to the output side of the first optical converging circuit 303. The second connection waveguides 304a and 304b are connected to the phase adjustment regions 308a and 308b. To the second optical converging circuit 306, and one output waveguide 307 is connected to the output side of the second optical converging circuit 306. The first optical merging circuit 303 has a function of merging light (laser light) oscillated from the DFB lasers 301a to 301j and propagated through the first connection waveguides 302a to 302j, and the second optical merging circuit. Reference numeral 306 has a function of joining the lights propagated through the second connection waveguides 304 a and 304 b to each other, and the light joined by the second optical joining circuit 306 is output from the output waveguide 307.

  The operation of the wavelength tunable laser of this example is as follows. Ten DFB lasers 301a to 301j are arranged at intervals of 30 microns, and each DFB laser has an electrode individually and operates independently. Each DFB laser has a diffraction grating on its active layer, and is set to oscillate at different wavelengths by setting the pitch of this diffraction grating to a different value for each DFB laser.

  Also in the wavelength tunable laser of this embodiment, a wide wavelength range of 30 nm or more can be obtained by selecting one of the ten DFB lasers 301a to 301j and controlling the element temperature, as in the conventional example. Can be covered.

  Then, the output light from any of the DFB lasers 301a to 301j enters the first optical converging circuit 303 through the S-shaped first connection waveguides 302a to 302j. In the first optical combining circuit 303, since the number of output ports is two with respect to the number of input optical ports of 10, input light to the first optical combining circuit 303 is provided in the second connection waveguides 304a and 304b. Lights having an intensity that is 1/10 of the intensity are output.

  The relative phases of the light incident on the second connection waveguides 304 a and 304 b are adjusted in the phase adjustment regions 308 a and 308 b and are incident on the second optical combining circuit 306. The second optical converging circuit 306 employs a 2 × 2 type in which the number of input ports is 2 and the number of output ports is two, and an output waveguide 307 is connected to one of the two output ports. At this time, the relative phases of the two lights incident on the second optical merge circuit 306 are adjusted to each other on the output side of the second optical merge circuit 306 by adjusting in the phase adjustment regions 308a and 308b. In this way, the signal is output to the output waveguide 307. As a result, the light incident on the second connection waveguides 304a and 304b is added to the output waveguide 307 and output without loss, so that the output waveguide 307 is compared with the output waveguide 104 in the conventional example shown in FIG. A double optical output is output to the output waveguide 307.

  In the configuration of the conventional example, only 1/10 of the light is coupled to the output waveguide 104 in the optical converging circuit 103, and the remaining 9/10 of the light is radiated as loss, and further becomes stray light as module characteristics. Was deteriorating. In contrast, in this embodiment, 2/10 of the laser oscillation light incident on the first optical converging circuit 303 can be extracted from the output waveguide 307 and radiated as a loss. Light also becomes 8/10, and stray light can be reduced compared to the conventional example. As a result, it is possible to reduce the optical loss due to the first optical converging circuit 303, enable high output operation, suppress stray light, and realize a wavelength variable light source having a high S / N ratio.

  An optical amplifier 305 can be further connected to the output waveguide 307. This makes it possible to compensate for the loss generated by the first optical combining circuit 303. In this embodiment, twice the intensity of light is incident on the optical amplifier 305 as compared with the optical amplifier 105 of the conventional example, so that the gain of the optical amplifier 305 required to obtain the same optical output as the conventional example is half, The injection current can be reduced, and the power consumption and size of the optical amplifier 305 can be reduced. Needless to say, when the current injection equivalent to that of the conventional example is performed on the optical amplifier 305, the output light intensity increases as compared with the conventional example.

  In this embodiment, a case where a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation has been described. However, if single mode laser oscillation is possible, it is necessary to limit to the DFB type. However, the same effect can be obtained even when a DBR type, a distributed active type (TDA-DFB-LD; see Non-Patent Document 2 and Patent Document 1), or the like is used.

  The first optical converging circuit 303 used in the present embodiment is not particularly limited in its configuration, and there is no optical confinement in the horizontal direction, so-called star couplers or funnel type couplers using a slab structure, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 306 is not particularly limited, and the same effect can be obtained regardless of which one is used, such as an MMI coupler or a directional coupler.

  In the present embodiment, the configuration in which the phase adjustment regions 308a and 308b are provided in the second connection waveguides 304a and 304b has been described. However, as described above, the second connection waveguides 304a and 304b are connected to the second connection waveguides 304a and 304b. If the relative phases of the two lights incident on the optical combining circuit 306 are strengthened to each other on the output side of the second optical combining circuit 306 and are output to the output waveguide 307, It is not always necessary to provide the phase adjustment regions 308a and 308b. For example, the relationship is such that the relative phases of two lights incident on the second optical merge circuit 306 from the second connection waveguides 304 a and 304 b reinforce each other on the output side of the second optical merge circuit 306. Thus, if the relative lengths of the second connection waveguides 304a and 304b are configured, the same effect can be obtained without providing a phase adjustment region.

  In addition, an asymmetrical configuration in which a phase adjustment region is provided in any one of the two second connection waveguides except for one in the case of two or more, and in the case of a plurality of three or more, under the following conditions: It can be used. Normally, when providing a region with an active function such as a phase adjustment region, it is incorporated in all waveguides so that the effective optical path length and light intensity considering the refractive index etc. can be aligned as much as possible. In many cases, it is structurally symmetric such that a control means such as an electric field and heat is applied only to a region necessary for this. However, even when configured asymmetrically, for example, a phase adjustment region is provided even if a phase difference caused by an effective optical path length difference is negligibly small or a phase difference exceeding one period is generated. In this embodiment, an asymmetric configuration can be used as long as it can be adjusted sufficiently on the waveguide side.

  However, when the phase adjustment regions 308a and 308b are provided symmetrically in the second connection waveguides 304a and 304b, an effect of increasing the manufacturing tolerance with respect to the length of the second connection waveguides 304a and 304b can be expected. As the phase adjustment means for the phase adjustment regions 308a and 308b, any means such as current injection, local temperature adjustment by a heater, electric field application, and light irradiation can be used.

  It should be noted that the structure and material of the laser used in this embodiment need not be particularly limited, and the effects described above can be obtained by adopting the configuration of this embodiment for the active layers of all the structures that are normally used. Obtainable. In other words, the active layer can be applied to any material such as InGaAsP, GaAs, AlGaAs, InGaAs, and GaInNAs, and the active layer structure is active regardless of whether it is bulk, MQW, quantum wire, or quantum dot. With respect to the waveguide structure in the layer region, similar effects can be obtained even when a pn buried structure, a ridge structure, a semi-insulating buried structure doped with Fe or Ru, a high mesa structure, or the like is used.

  The substrate is not limited to the n-type substrate, and it goes without saying that the same effect can be obtained with a p-type, a semi-insulating type, or the like. Further, there are no restrictions on the waveguide structures such as the connection waveguide and the optical converging circuit, and the above-described effects can be obtained in any waveguide structure. In other words, even when all waveguide structures including the ridge type, buried type, and high mesa type are used, the same effect can be obtained by using the arrangement as in this embodiment.

(Example 2)
FIG. 4 is a diagram showing a wavelength tunable laser according to the present embodiment. In the first embodiment shown in FIG. 3, a case where a 2-input 1-output optical converging circuit is used as the second optical converging circuit is shown. Yes. In the figure, 401a to 401j are DFB lasers, 402a to 402j are first connection waveguides, 403 is a first optical combining circuit, 404a and 404b are second connection waveguides, 405 is an optical amplifier, and 406 is a second connection waveguide. An optical converging circuit, 407 indicates an output waveguide, and 408a and 408b indicate phase adjustment regions, respectively.

  In the present embodiment, the operation can be described by replacing 301 to 308 in the first embodiment with 401 to 408, and the operation is exactly the same as that in the first embodiment.

  Also in this embodiment, a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation. However, if single mode laser oscillation is possible, it is not necessary to limit to the DFB type. The same effect can be obtained even when a DBR type, a distributed activation type, or the like is used.

  The first optical converging circuit 403 used in the present embodiment is not particularly limited in its configuration, and there is no optical confinement in the horizontal direction, so-called star couplers or funnel type couplers using a slab structure, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 406 used in this embodiment is not particularly limited, and the same applies regardless of which one is used, such as an MMI coupler, a directional coupler, or a Y-shaped combiner circuit. Effects can be obtained.

(Example 3)
FIG. 5 is a diagram showing a wavelength tunable laser according to the present embodiment. A tunable laser using a DFB array in which a DFB laser is used as a waveguide type laser cavity capable of oscillating a single mode and a plurality of these are aligned. The structure is shown. In the figure, 501a to 501j are DFB lasers, 502a to 502j are first connection waveguides, 503 is a first optical converging circuit, 504a and 504b are second connection waveguides, 505a and 505b are optical amplifiers, and 506 is a first amplifier. 2, an optical waveguide 507, and 508 a and 508 b indicate phase adjustment regions, respectively.

  Also in the present embodiment, by replacing 301 to 308 in the first embodiment with 501 to 508, the operation can be understood as in the first embodiment. That is, the ten DFB lasers 501a to 501j have electrodes individually and operate independently. Each DFB laser has a diffraction grating on its active layer, and is set to oscillate at different wavelengths by setting the pitch of this diffraction grating to a different value for each DFB laser.

  Also in the wavelength tunable laser according to the present embodiment, similarly to the first embodiment, by selecting one of the ten DFB lasers 501a to 501j and controlling the element temperature, a wide wavelength of 30 nm or more can be obtained. The range can be covered.

  The output light from any of the DFB lasers 501a to 501j enters the first optical converging circuit 503 through the S-shaped first connection waveguides 502a to 502j. In the first optical combining circuit 503, the number of output ports is two with respect to the number of input optical ports of 10, and therefore, the input light to the first optical combining circuit 503 is input to the second connection waveguides 504a and 504b. Lights having an intensity that is 1/10 of the intensity are output.

  The relative phases of the light incident on the second connection waveguides 504a and 504b are adjusted in the phase adjustment regions 508a and 508b, and are incident on the second optical merge circuit 506. The second optical converging circuit 506 employs a 2 × 2 type in which the number of input ports is 2 and the number of output ports is two, and an output waveguide 507 is connected to one of the two output ports. At this time, the relative phases of the two lights incident on the second optical merging circuit 506 are adjusted to each other on the output side of the second optical merging circuit 506 by adjusting the phase adjustment regions 508a and 508b. In this way, the signal is output to the output waveguide 507.

In this embodiment, since the optical amplifiers 505a and 505b are connected to the second connection waveguides 504a and 504b so as to be subordinately connected to the phase adjustment regions 508a and 508b, the second connection waveguide 504a. And 504b are amplified by an intensity G ₁ times, aligned in intensity, and adjusted in phase by the phase adjustment regions 508a and 508b, and enter the second optical confluence circuit 506. As a result, the light incident on the connection waveguides 504a and 504b is added to the output waveguide 507 in an amplified state and added without loss.

  In this way, the first embodiment shown in FIG. 3 and the present embodiment operate according to the same operation principle except that the positions of the optical amplifiers 305 and 505a and 505b are different.

Here, an operational difference between the present embodiment and the first embodiment will be described. FIG. 6 is a diagram for explaining the relationship between the input light intensity P _in and the output light intensity P _out of the optical amplifier, in which the solid line indicates the input / output characteristics of the semiconductor optical amplifier 305 or 505a, 505b, and the broken line indicates the input. The ratio of input / output light intensity when the light intensity is small, that is, a straight line (P _out = G ₀ · P _in ) extrapolating the linear gain G ₀ in the unsaturated state is shown.

FIG. 6 shows that when the input light intensity is weak, the input light is amplified and output by G ₀ times, but when the input light intensity increases, the gain is saturated and decreases from G ₀ times. Show. Now, in this embodiment, the first optical coupling circuit 503, when the light intensity incident on the second connecting waveguides 504a and 504b and P _in1, the light intensity of P _in1 is a phase adjusting region 508a or 508b The light passes through and enters the optical amplifier 505a or 505b. As shown in FIG. 6, due to the relationship between the input light intensity P _in and the output light intensity P _out of the optical amplifiers 505a and 505b, the gain when the input light intensity is P _in1 is G ₀ , and the optical amplifiers 505a and 505b The outputs are P _out1 = G ₀ · P _in1 , respectively. The outputs of the optical amplifiers 505a and 505b are incident on the second optical junction circuit 506. As described above, since the outputs of the optical amplifiers 505a and 505b are added and output without loss to the output waveguide 507, the output light intensity P _out of the output waveguide 507 is P _out = 2P _out1 = 2G _0. It becomes P _in1 .

On the other hand, considering Example 1 shown in FIG. 3, the light intensity incident on the second connection waveguides 304a and 304b from the first optical converging circuit 303 is equivalent to that of the present example shown in FIG. Because there is, it becomes P _in1 . The light having the intensity of P _in1 passes through the phase adjustment region 308a or 308b and enters the second optical combining circuit 306. As described above, since the outputs of the phase adjustment regions 308a and 308b are added and output without loss to the output waveguide 307, the output light intensity P ₃₀₇ of the output waveguide ₃₀₇ is P ₃₀₇ = 2P _in1. . Since the light of P ₃₀₇ = 2P _in1 enters the optical amplifier 305 as input light, the input light intensity P _in the relationship between the input light intensity P _in and the output light intensity P _out of the optical amplifier 305 shown in FIG. _{From the} amplification factor at _in = 2P _in1 = P _in2, the output light intensity P _out of the optical amplifier 305 is P _out = P _out2 <2G ₀ · P _in1 . This indicates that since the input light intensity of the optical amplifier is doubled, the gain of the optical amplifier is saturated and the output light intensity is less than double.

  As described above, by arranging the optical amplifiers 505a and 505b between the first optical combining circuit 503 and the second optical combining circuit 506, the input light intensity to the optical amplifiers 505a and 505b causes gain saturation. Even when it becomes so strong, it is possible to obtain a larger output than when the optical amplifier is arranged on the output side of the second optical converging circuit.

  In this embodiment, a case where a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation has been described. However, if single mode laser oscillation is possible, it is necessary to limit to the DFB type. However, the same effect can be obtained even when a DBR type, a distributed active type, or the like is used.

  Further, the first optical converging circuit 503 used in this embodiment is not particularly limited in its configuration, and there is no optical confinement in the horizontal direction, so-called star coupler or funnel type coupler using a slab structure, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 506 is not particularly limited, and the same effect can be obtained regardless of which one is used, such as an MMI coupler or a directional coupler. As the phase adjustment means for the phase adjustment regions 508a and 508b, any means such as current injection, local temperature adjustment by a heater, electric field application, and light irradiation can be used.

Example 4
FIG. 7 is a diagram showing a wavelength tunable laser according to the present embodiment. In the third embodiment shown in FIG. 5, a case where a 2-input 1-output optical combining circuit is used as the second optical combining circuit is shown. Yes. In the figure, 701a to 701j are DFB lasers, 702a to 702j are first connection waveguides, 703 is a first optical combining circuit, 704a and 704b are second connection waveguides, 705a and 705b are optical amplifiers, and 706 is a first connection waveguide. 2, an optical waveguide 707, and 708 a and 708 b indicate phase adjustment regions, respectively.

  In this embodiment, the operation can be explained by replacing 501 to 508 in Embodiment 3 with 701 to 708, and the operation is exactly the same as that in Embodiment 3.

  Also in this embodiment, a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation. However, if single mode laser oscillation is possible, it is not necessary to limit to the DFB type. The same effect can be obtained even when a DBR type, a distributed activation type, or the like is used.

  Further, the first optical converging circuit 703 used in this embodiment is not particularly limited in its configuration, and a so-called slab structure star coupler or funnel type coupler that does not have optical confinement in the horizontal direction, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 706 used in this embodiment is not particularly limited, and the same is true regardless of which is used, such as an MMI coupler, a directional coupler, or a Y-shaped splitter circuit. Effects can be obtained.

(Example 5)
FIG. 8 is a diagram showing a wavelength tunable laser according to the present embodiment, and shows a case where an optical modulator is arranged on the output side of the optical amplifier in the output section of the structure of the second embodiment shown in FIG. . In the figure, 801a to 801j are DFB lasers, 802a to 802j are first connection waveguides, 803 is a first optical converging circuit, 804a and 804b are second connection waveguides, 805 is an optical amplifier, and 806 is a second optical waveguide. An optical combining circuit, 807 is an output waveguide, 808a and 808b are phase adjustment regions, and 809 is an optical modulator.

  In this embodiment, the operation can be explained by replacing 401 to 408 in Embodiment 2 with 801 to 808. The operation up to the optical modulator 809 is exactly the same as that in Embodiment 2. In this embodiment, an optical modulator 809 is connected to the configuration of the second embodiment shown in FIG. 4, that is, an optical modulator 809 is added, and the structure of a wavelength tunable light source with a modulator is shown. .

  As the optical modulator 809 used in this embodiment, there is no need to provide restrictions on the modulation method, and intensity modulation, phase modulation, a modulation method combining intensity modulation and phase modulation, or the like can be applied. With regard to this structure, any optical modulator can be used regardless of an electroabsorption (EA) type optical modulator, a Mach-Zehnder type modulator, or the like.

  Also in this embodiment, a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation. However, as in the second embodiment, if single mode laser oscillation is possible, the DFB type is used. It is not necessary to limit, and the same effect can be obtained even when a DBR type, a distributed activation type, or the like is used.

  The first optical converging circuit 803 used in the present embodiment is not particularly limited in its configuration, and there is no optical confinement in the horizontal direction, so-called star couplers or funnel type couplers using a slab structure, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 806 used in the present embodiment is not particularly limited, and the same applies regardless of which one is used, such as an MMI coupler, a directional coupler, or a Y-shaped combiner circuit. Effects can be obtained.

  In this embodiment, the optical modulator 809 is arranged on the output side of the optical amplifier 805, but the optical modulator 809 can also be arranged on the input side of the optical amplifier 805. However, when the modulated optical signal is incident on the optical amplifying element, it is easy to be affected by the pattern effect due to gain saturation, so care must be taken. When the optical modulator 809 is arranged on the output side of the optical amplifier 805 as in the present embodiment, the light incident on the optical amplifier 805 becomes light of a certain intensity that is not intensity-modulated. There is an advantage that the pattern effect does not occur even if the gain is saturated.

  In this embodiment, the configuration in which the optical modulator 809 is connected to the optical amplifier 805 has been described. However, only the optical modulator 809 is provided on the output side of the second optical converging circuit 806 without arranging the optical amplifier 805. Similar effects can be obtained in the arrangement.

  In the present embodiment, the configuration in which the optical modulator is connected to the structure of the second embodiment shown in FIG. 4 has been described. However, the present embodiment is applicable to any of the first to fourth embodiments. Similarly, it is obvious that an optical modulator can be connected, and the above-described various configuration examples can be applied as they are to the presence / absence of an optical amplifier and the positional relationship between the optical amplifier and the optical modulator.

(Example 6)
FIG. 9 is a diagram showing a wavelength tunable laser according to the present embodiment. In the second connection waveguide having the structure of the fourth embodiment shown in FIG. 7, an optical phase modulator is arranged on the output side of the optical amplifier. Shows the case. In the figure, 901a to 901j are DFB lasers, 902a to 902j are first connection waveguides, 903 is a first optical converging circuit, 904a and 904b are second connection waveguides, 905a and 905b are optical amplifiers, and 906 is a first amplifier. 2, an optical waveguide 907, phase adjustment regions 908 a and 908 b, and optical phase modulators 909 a and 909 b, respectively.

  In this embodiment, the operation can be explained by replacing 701 to 708 in Embodiment 4 with 901 to 908, and the operation is exactly the same as that of Embodiment 4. In the present embodiment, optical phase modulators 909a and 909b are connected to the configuration of the fourth embodiment shown in FIG. 7, and the structure of a wavelength tunable light source with a modulator is shown.

  The principle of modulation in this embodiment is as follows. Now, the relative phases of the two lights incident on the second optical merge circuit 906 are strengthened to each other on the output side of the second optical merge circuit 906 and output to the output waveguide 907. It is assumed that phase adjustment regions 908a and 908b in the two connection waveguides 904a and 904b are set. When the phase of the signal light is changed by π in the optical phase modulator 909a or 909b, the signal lights that have been output to the output waveguide 907 so far cancel each other out on the output side of the second optical combining circuit 906. , The signal is not output to the output waveguide 907. Therefore, when the phase of the signal light is changed to 0, π, 0, π in the optical phase modulator 909a or 909b, the signal light intensity is modulated.

  The optical phase modulator is modulated by changing the phase of the signal light by π on one of the optical phase modulators 909a or 909b, generating an intensity-modulated signal, + π / 2 for one, and- It is also possible to generate an intensity modulation signal by performing push-pull driving that changes by π / 2, and by changing by + (m−1) π / m on the other hand, by + π / m on the other hand, An intensity modulated signal can be generated. That is, when changing by M1 on the one hand and -M2 on the other hand, an intensity modulation signal is generated if the relationship of phase difference [M1-M2] = ± π is established. The modulation ratio of the optical phase modulators 909a and 909b and the characteristics of the generated signal are the same as those of a normal Mach-Zehnder modulator, and the chirp can be controlled by the modulation ratio.

  Further, when one of the optical phase modulators 909a and 909b is changed by + π and the other is changed by −π, a chirpless phase modulation signal can be output. When the function up to that point is not necessary, the optical phase modulators may not be provided in all the second connection waveguides for the same reason as described for the configuration of the phase adjustment region in the first embodiment. For example, in this embodiment, an optical phase modulator is provided only on one side of the two second connection waveguides 904a and 904b, and the signal light passing through the second connection waveguide on the side where the optical phase modulator is provided is provided. Even if the phase is changed by 0, π, or 0, −π, an intensity modulation signal can be generated.

  Also in this embodiment, a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation. However, as in the fourth embodiment, if single mode laser oscillation is possible, the DFB type is used. It is not necessary to limit, and the same effect can be obtained even when a DBR type, a distributed activation type, or the like is used.

  Further, the first optical converging circuit 903 used in this embodiment is not particularly limited in its configuration, and there is no optical confinement in the horizontal direction, so-called star coupler or funnel type coupler using a slab structure, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 906 used in this embodiment is not particularly limited, and the same applies regardless of which one is used, such as an MMI coupler, a directional coupler, or a Y-shaped combiner circuit. Effects can be obtained.

  In the present embodiment, the optical phase modulators 909a and 909b are arranged on the output side of the optical amplifiers 905a and 905b in the second connection waveguides 904a and 904b, but the optical phase modulators 909a and 909b are optical amplifiers 905a and 905b. It is also possible to arrange on the input side. In addition, in the configuration of this embodiment, since the outputs of the optical phase modulators 909a and 909b are not accompanied by intensity modulation, even when the optical phase modulators 909a and 909b are arranged on the input side of the optical amplifiers 905a and 905b, Since the light incident on the amplifiers 905a and 905b becomes light of constant intensity that is not intensity-modulated, there is no concern that a pattern effect will occur even if the gain of the optical amplifiers 905a and 905b is saturated.

  In the present embodiment, the optical phase modulators 909a and 909b are arranged on the output side of the phase adjustment regions 908a and 908b in the second connection waveguides 904a and 904b, but the second connection waveguides 904a and 904b If so, the position of the optical phase modulators 909a and 909b may be anywhere.

  In the present embodiment, the configuration in which the optical phase modulator is connected to the structure of the fourth embodiment shown in FIG. 7 has been described. However, the same applies to any of the first to fifth embodiments. Needless to say, an optical phase modulator can be connected.

  In the present embodiment, the case where the phase adjustment regions 908a and 908b and the optical phase modulators 909a and 909b are connected to the second connection waveguides 904a and 904b, respectively, has been described. The operation itself of adjusting (modulating) the phase is the same between the phase adjustment regions 908a and 908b and the optical phase modulators 909a and 909b. However, in the phase adjustment regions 908a and 908b, once calibration is performed so that the output from the second optical converging circuit 906 is maximized, and then fine adjustment can be performed in response to disturbance such as temperature change. Well, stability is important. On the other hand, in the optical phase modulators 909a and 909b, the operation speed is important in order to cope with a high-speed modulation signal. Therefore, normally, it is desirable to divide the phase adjustment regions 908a and 908b from the optical phase modulators 909a and 909b and perform optimization according to their respective purposes.

  On the other hand, depending on the configuration and the required operation speed, the phase adjustment regions 908a and 908b and the optical phase modulators 909a and 909b can be combined. In this case, for example, the phase adjustment regions 708a and 708b in FIG. 7 are replaced with the phase adjustment regions 908a and 908b and the optical phase modulators 909a and 909b, and the biases of the optical phase modulators 909a and 909b are set for phase adjustment. From there, a driving condition may be adopted in which the phase is modulated by the amount of phase fluctuation necessary for intensity modulation or phase modulation.

(Example 7)
FIG. 10 is a diagram showing a wavelength tunable laser according to the present embodiment, and shows a case where the number of second connection waveguides is four in the structure of the fifth embodiment shown in FIG. In the figure, 1001a to 1001j are DFB lasers, 1002a to 1002j are first connection waveguides, 1003 is a first optical combining circuit, 1004a to 1004d are second connection waveguides, 1005 is an optical amplifier, and 1006 is a second connection. An optical converging circuit, 1007 is an output waveguide, 1008a to 1008d are phase adjustment regions, and 1009 is an optical modulator.

  In the present embodiment, the operation can be described by replacing 801 to 809 in the fifth embodiment with 1001 to 1009, and the operation is exactly the same as that of the fifth embodiment.

  In the fifth embodiment, there are two second connection waveguides 804a and 804b, and the relative phases of the two lights incident on the second optical converging circuit 806 are changed in phase adjustment regions 808a and 808b. By adjusting, the signals are output to the output waveguide 807 so as to strengthen each other on the output side of the second optical converging circuit 806.

  On the other hand, in the present embodiment, there are four second connection waveguides 1004a to 1004d, but even when there are four second connection waveguides, the respective waveguides lead to the second optical merge circuit 1006. By adjusting the relative phases of the four incident light beams in the phase adjustment regions 1008a to 1008d, they are output to the output waveguide 1007 so as to strengthen each other on the output side of the second optical merge circuit 1006. ing.

  As a result, since light incident on the connection waveguides 1004a to 1004d is added and output without loss to the output waveguide 1007, 4/10 of the laser oscillation light incident on the first optical combining circuit 1003 is output. The light can be extracted from the output waveguide 1007, and the light radiated as a loss is also 6/10. The output waveguide 1007 has twice the intensity of light as compared with the fifth embodiment shown in FIG. And stray light due to radiation can be suppressed.

  Thus, in the configuration of the present invention, as long as the number of the second connection waveguides is two or more, the same effect can be obtained regardless of the number of the second connection waveguides, and the element output increases as the number increases. In addition, stray light due to radiation can be suppressed.

  The optical modulator 1009 used in this embodiment does not need to be restricted in its modulation method, and may be intensity modulation, phase modulation, or a modulation method in which intensity modulation and phase modulation are combined. Regarding the structure, any modulator can be used regardless of an electroabsorption (EA) modulator, a Mach-Zehnder modulator, or the like.

  Also in this embodiment, a DFB type laser cavity is used as a waveguide type laser cavity capable of single mode laser oscillation. However, as in other embodiments, if a single mode laser oscillation is possible, a DFB type is used. It is not necessary to limit to the same, and the same effect can be obtained even when a DBR type, a distributed activation type, or the like is used.

  Further, the first optical converging circuit 1003 used in this embodiment is not particularly limited in its configuration, and a so-called slab structure star coupler or funnel type coupler that does not have optical confinement in the horizontal direction, The same effect can be obtained regardless of the configuration of the optical merging / branching circuit having a plurality of input ports and a plurality of output ports, such as an MMI coupler using the interference effect of a multimode waveguide. Can do. The configuration of the second optical combining circuit 1006 used in this embodiment is not particularly limited, and the same applies regardless of which one is used, such as an MMI coupler, a directional coupler, or a Y-shaped combiner circuit. Effects can be obtained.

  In this embodiment, the optical modulator 1009 is arranged on the output side of the optical amplifier 1005, but the optical modulator 1009 can also be arranged on the input side of the optical amplifier 1005. However, when the modulated optical signal is incident on the optical amplifying element, it is easy to be affected by the pattern effect due to gain saturation, so care must be taken. When the optical modulator 1009 is arranged on the output side of the optical amplifier 1005 as in this embodiment, the light incident on the optical amplifier 1005 becomes light of a constant intensity that is not intensity-modulated. There is an advantage that the pattern effect does not occur even if the gain is saturated.

  In this embodiment, the configuration in which the optical modulator 1009 is connected to the optical amplifier 1005 has been described. However, only the optical modulator 1009 is provided on the output side of the second optical combining circuit 1006 without arranging the optical amplifier 1005. Similar effects can be obtained in the arrangement.

  In the present embodiment, the configuration in which the number of the second connection waveguides is increased in the structure of the fifth embodiment shown in FIG. 8 is described. However, for any of the first to fifth embodiments described above. However, as in the present embodiment, the number of second connection waveguides can be increased, whereby the same effect can be obtained.

(Example 8)
FIG. 11 is a diagram showing a wavelength tunable laser according to the present embodiment, and shows a cross-sectional structure of a waveguide type laser cavity. In the figure, 1101 is an n-InP substrate, 1102 is an InGaAsP-MQW active layer, 1103a and 1103b are InGaAsP-SCH layers, 1104 is a p-InP cladding, 1105 is a p-InGaAsP contact layer, and 1106a and 1106b are Ru-doped InP buried layers. The layer 1107 is a p-side electrode, and 1108 is an n-side electrode.

  This embodiment is characterized in that a buried structure is used for the stripe structure of the waveguide type laser cavity, and ruthenium (Ru) doped semi-insulating crystals are used for the buried layers 1106a and 1106b. The laminated structure such as the active layer other than these is the same as that in the above-described embodiment. Not only the waveguide type laser cavity but also a waveguide type optical modulator may have a stripe structure, and the stripe structure may be an embedded type structure embedded with a ruthenium (Ru) doped semi-insulating crystal.

  The laser structure of this example is manufactured as follows. The above-mentioned laminated structure such as the active layer is processed into a mesa stripe shape in the [011] direction by dry etching using methane gas or the like using the silicon oxide subjected to stripe processing as a mask. Next, a semi-insulating InP crystal doped with ruthenium is buried and grown on both sides of the mesa stripe by a normal metal organic vapor phase epitaxy (MOVPE). Subsequent electrode forming steps and the like are the same as those in a normal semiconductor laser process.

  By using a ruthenium-doped semi-insulating crystal for the buried layers 1106a and 1106b, there is no mutual diffusion of Zn and Ru, which are dopants of the p-type semiconductor, and high resistance embedding is possible, without increasing the device capacitance. In addition, the device can be embedded without degrading the performance of the active layer. The laser of this example showed a direct modulation characteristic exceeding 10 GHz.

Example 9
FIG. 12 shows the configuration of the optical module of the present embodiment using the semiconductor lasers of the first to eighth embodiments. In the figure, 1201 is a semiconductor laser, 1202 is a Peltier element, 1203 is a lens, 1204 is an isolator, 1205 is a wavelength locker, 1206 is a lens, 1207 is a fiber, 1208 is a metal case, 1209 is a lens holder, 1210 is a submount, and 1211 Indicates Peltier elements.

  The optical module according to the present embodiment includes the semiconductor laser 1201 described in any one of the first to eighth embodiments as an optical semiconductor element mounted on the submount 1210, and is emitted from the semiconductor laser 1201. A first lens 1203 and a second lens 1206 are provided that are aligned so that light is coupled to the optical fiber 1207 with low loss. The first lens 1203 is housed in a metal housing 1208. An isolator 1204 is provided between the first lens 1203 and the second lens 1206 to prevent the reflected light from entering the semiconductor laser 1201.

  The submount 1210 is mounted on a Peltier element 1202 for temperature control. The temperature of the Peltier element 1202 is controlled from the outside via electric wiring. The oscillation wavelength of the semiconductor laser 1201 can be changed by the temperature change of the semiconductor laser 1201 accompanying the temperature fluctuation of the Peltier element 1202.

  In order to control the wavelength and power of light output from the semiconductor laser 1201, a wavelength locker 1205 is provided. The wavelength locker 1205 is mounted on the Peltier element 1211. In the wavelength locker 1205, a part of the incident light is reflected by the semitransparent mirror, is incident on the first photodiode (power monitor), and the other part is incident on the second photodiode via the wavelength filter. Let me.

  Further, the light that has not been reflected by the above-described semi-transparent mirror is condensed on the optical fiber 1207 by the lens 1206 as transmitted light. Light received by each photodiode is converted into electricity and input to a control device outside the optical module. The control device controls the current (operating current) input to the semiconductor laser 1201 in accordance with the input currents from the first and second photodiodes, and stabilizes the optical output of each wavelength. Further, this control device controls the input current to the Peltier element 1202 to change or stabilize the oscillation wavelength of the semiconductor laser 1201.

  The first lens 1203 converts light emitted from the semiconductor laser 1201 into parallel rays. After the position of the lens 1203 is adjusted, the lens 1203 is fixed on the submount 1210 via the lens holder 1209. Light that has been converted into parallel rays by the first lens 1203 and condensed by the second lens 1206 via the isolator 1204 and the wavelength locker 1205 is connected to the optical fiber 1207.

  As a result of operating the optical module of this example, CW power +7 dBm or more is obtained with a stability of wavelength accuracy of ± 1 GHz or less at all wavelengths of 97 channels and C band (1.530 μm to 1.560 μm) at 50 GHz intervals. It was.

  The present invention is suitable for a wavelength tunable laser having a large wavelength tunable width used in a wavelength division multiplexing optical network.

101a-j... DFB lasers 102a-j... S-shaped connection waveguide 103... Optical converging circuit 104. j ... S-shaped connection waveguide 303 ... optical converging circuit 304a, b ... connection waveguide 305 ... optical amplifier 306 ... optical converging circuit 307 ... output waveguide 308a, b. Phase adjustment regions 401a to j DFB lasers 402a to j S-shaped connection waveguide 403 Optical coupling circuit 404a, b Connection waveguide 405 Optical amplifier 406 Optical converging circuit 407: output waveguides 408a, b ... phase adjustment regions 501a-j ... DFB lasers 502a-j ... S-shaped connecting waveguides 503 ... optical converging circuits 504a, b ... Connection waveguide 505a b... Optical amplifier 506... Optical converging circuit 507... Output waveguide 508 a, b... Phase adjustment region 701 a to j... DFB laser 702 a to j. Optical coupling circuit 704a, b ... Connection waveguide 705a, b ... Optical amplifier 706 ... Optical coupling circuit 707 ... Output waveguide 708a, b ... Phase adjustment region 801a-j .... DFB lasers 802a-j ... S-shaped connecting waveguide 803 ... Optical converging circuit 804a, b ... Connecting waveguide 805a ... Optical amplifier 806 ... Optical converging circuit 807 ... Output Waveguides 808a, b ... phase adjustment region 809 ... modulators 901a-j ... DFB lasers 902a-j ... S-shaped connection waveguides 903 ... optical converging circuits 904a, b ... Connection waveguides 905a, b ... Amplifier 906 ... Optical converging circuit 907 ... Output waveguides 908a, b ... Phase adjustment regions 909a, b ... Optical phase modulators 1001a to j ... DFB lasers 1002a to j ... S-shaped Type connecting waveguide 1003... Optical converging circuit 1004 a to d... Connecting waveguide 1005... Optical amplifier 1006. ... modulator 1101 ... n-InP substrate 1102a ... InGaAsP-MQW active layer 1103a, b ... InGaAsP-SCH layer 1104 ... p-InP cladding 1105 ... p-InGaAsP contact layer 1106a B ... Ru doped InP buried layer 1107 ... electrode 1108 ... electrode 1201 ... semiconductor laser 1202 ... Luctier element 1203 ... Lens 1204 ... Isolator 1205 ... Wavelength locker 1206 ... Lens 1207 ... Fiber 1208 ... Metal housing 1209 ... Lens holder 1210 ... Submount 1211 ...・ Peltier element

Claims (13)

A plurality of waveguide laser cavities each capable of single mode lasing at different wavelengths;
A first connecting waveguide connected to each of the plurality of waveguide-type laser cavities;
A plurality of the first connection waveguides connected to each other, a first optical merging circuit for merging the laser light oscillated from the waveguide type laser cavity and propagated through the first connection waveguide;
At least two second connection waveguides connected to the output side of the first optical converging circuit;
A second optical merging circuit for connecting the at least two second connection waveguides and merging the laser beams respectively propagating through the second connection waveguides;
One output waveguide connected to the output side of the second optical merging circuit and outputting the laser beam merged by the second optical merging circuit;
A semiconductor laser characterized in that a wavelength tunable light source is formed by oscillating laser light from a desired waveguide laser cavity. The semiconductor laser according to claim 1, wherein
A phase adjustment region for adjusting the phase of the laser light propagating through the second connection waveguide is provided in all the second connection waveguides or in the remaining second connection waveguides except for one. A semiconductor laser provided. In the semiconductor laser according to claim 1 or 2,
2. A semiconductor laser comprising a waveguide type optical amplifier for amplifying laser light merged by the first optical merging circuit or the second optical merging circuit. The semiconductor laser according to claim 3, wherein
A semiconductor laser characterized in that the waveguide type optical amplifier is provided in each of the second connection waveguides. The semiconductor laser according to claim 3, wherein
A semiconductor laser comprising the waveguide type optical amplifier provided in the output waveguide. In the semiconductor laser according to any one of claims 1 to 5,
A semiconductor laser characterized in that the first optical converging circuit is a multimode interference coupler or a funnel coupler. In the semiconductor laser according to any one of claims 1 to 6,
A semiconductor laser characterized in that the second optical merging circuit is one of a multimode interference coupler, a directional coupler, and a Y-shaped optical merging device. In the semiconductor laser according to any one of claims 1 to 7,
A semiconductor laser comprising an optical modulator that modulates at least one of the intensity and phase of laser light on the output side of the second optical converging circuit. The semiconductor laser according to claim 8, wherein
A semiconductor laser, wherein the optical modulator is an electroabsorption modulator or a Mach-Zehnder modulator. In the semiconductor laser according to any one of claims 1 to 7,
Adjust the phase difference between the laser beams propagating through the second connection waveguide to all the second connection waveguides, or to the remaining second connection waveguide except for one, A semiconductor laser comprising an optical phase modulator for modulating light intensity. In the semiconductor laser according to any one of claims 1 to 10,
A semiconductor laser characterized in that at least one of the waveguide laser cavity or the optical modulator is processed into a stripe structure, and both sides of the stripe structure are embedded with a ruthenium-doped semi-insulating semiconductor crystal. A semiconductor laser according to any one of claims 1 to 11,
A first lens that converts light emitted from the semiconductor laser into parallel rays;
A second lens for condensing the light as parallel rays;
An isolator disposed between the first lens and the second lens to prevent reflection of the light to the semiconductor laser;
An optical module, wherein the collected light is coupled to an optical fiber and output. The optical module according to claim 12,
An optical module comprising a wavelength locker for controlling the wavelength and power of light emitted from the semiconductor laser.

Images