JP2017017077A - Semiconductor laser light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser light source having a response band of approximately 100 Gb/s while preventing a sharp degradation in response sensitivity in an area of resonant frequency or more.SOLUTION: A semiconductor laser light source 100 includes: a distributed feedback type semiconductor laser part 110 that includes a resonator optical loss modulation area 102 and a distributed feedback type semiconductor laser area 101; and an outside resonator 105 that reflects oscillation light which is oscillated from the distributed feedback type semiconductor laser part 110 and outputs a beam of feedback light to the distributed feedback type semiconductor laser part. The resonator optical loss modulation area 102 modulates the loss of the feedback light.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semiconductor laser light source capable of controlling oscillation light intensity or optical frequency at high speed by applying an electric signal.

Semiconductor lasers are expected to serve as a light source that can contribute to downsizing of devices and reduction of power consumption because direct modulation of injection current can modulate output light intensity or oscillation light frequency. It was. During semiconductor laser operation by this direct modulation, an increase in sensitivity at a frequency called the resonance frequency determined by the physical constants of the semiconductor material is observed, and the response sensitivity decreases sharply in the frequency range beyond that, so the response band is the resonance frequency. It was decided by. The resonance frequency _fr is controlled by the physical constant of the semiconductor material, and is approximately expressed as (Equation 1) below. Here, A _g is Parameta describes the increase rate of gain due to the carrier density increases, called differential gain, tau _p is the photon lifetime, the tau _s represents a carrier lifetime.

As can be seen from (Equation 1), in order to increase the resonance frequency response band, it is necessary to increase the differential gain and shorten the photon lifetime τ _p and the carrier lifetime τ _s , but the carrier lifetime τ _s This shortening leads to an increase in the laser threshold value, and there is a concern about an increase in power consumption, which is not practical.

Wataru Kobayashi, Takashi Tadokoro, Takeshi Fujisawa, Naoki Fujiwara, Takayuki Yamanaka and Fumiyoshi Kano, “40-Gbps Direct Modulation of 1.3- ・ m InGaAlAs DFB Laser in Compact TO-CAN Package”, Optical Fiber Communication Conference / National Fiber Optic Engineers Conference 2011, no. OWD2, pp. 1-3, Los Angeles, United States, March. 2011 Jochen Kreissl, Valeria Vercesi, Ute Troppenz, Tom Gaertner, Wolfgang Wenisch, and Martin Schell, “Up to 40-Gb / s Directly Modulated Laser Operating at Low Driving Current: Buried-Heterostructure Passive Feedback Laser (BH-PFL)”, IEEE Photon. Technol. Lett., Vol. 24, no. 5, pp. 362-364, March 2012 Mindaugas Radziunas, Annegret Glitzky, Uwe Bandelow, Matthias Wolfrum, Ute Troppenz, Jochen Kreissl, and Wolfgang Rehbein, “Improving the Modulation Bandwidth in Semiconductor Lasers by Passive Feedback,” IEEE Journal of Selected Topics in Quantum Electronics., Vol. 13, no . 1, pp. 136-142, January 2007

For shortening the photon lifetime τ _p , shortening the semiconductor laser resonator length is effective. Also introduced strain into the active layer of the semiconductor laser, the increase in differential gain A _g by adopting a multi-quantum well structure that increases the resonance frequency itself can be realized. By introducing these techniques, a 40 Gb / s operation is realized in a distributed feedback (DFB) semiconductor laser having a resonator length of 100 μm (see, for example, Non-Patent Document 1).

  However, when a single resonator is further promoted, there is a problem that a response band is reduced due to an increase in photon density inside the resonator and an effect of heat generation. For this reason, no further increase in speed can be expected by controlling the physical constants of the materials constituting the semiconductor laser.

  There is a report of a laser called a passive feedback laser, in which a semiconductor laser is provided with an external cavity structure to induce a photon resonance effect by the interaction between the longitudinal modes of the semiconductor laser resonator in the semiconductor laser light source, thereby expanding the band. Yes (for example, see Non-Patent Document 2).

  However, in the configuration described in Non-Patent Document 2, the response sensitivity rapidly deteriorates in the frequency region higher than the resonance frequency of the semiconductor laser and immediately falls below the 3 dB band. Since it is necessary to set the frequency of the photon resonance effect so as to obtain a 3 dB band, in the configuration described in Non-Patent Document 2, the frequency of the photon resonance effect cannot be set sufficiently high. Similarly, the configuration described in Non-Patent Document 3 can also be set only to a photon resonance effect frequency of about 30 GHz. Because of this situation, the response speed of the semiconductor laser light source has been limited to about 30 to 35 GHz as shown in FIG. 1, regardless of which method described in Non-Patent Documents 1 to 3.

  Thus, the realization of the technology for dramatically increasing the response band of the conventional direct modulation laser, which has been limited by the material property constant of the material, and the realization of the semiconductor laser operating at a signal speed of over 100 Gb / s were major issues. .

  In order to achieve such an object, a semiconductor laser light source according to claim 1 includes a distributed feedback semiconductor laser section including a resonator optical loss modulation region and a distributed feedback semiconductor laser region, and the distributed feedback semiconductor laser. An external resonator unit that reflects the oscillation light oscillated from the unit and outputs feedback light to the distributed feedback semiconductor laser unit, and the resonator optical loss modulation region performs loss modulation of the feedback light It is characterized by that.

  The semiconductor laser light source according to claim 2 is the semiconductor laser light source according to claim 1, wherein the resonator light loss modulation region has a dielectric constant greater than that of the resonator light loss modulation region. 2. The semiconductor laser light source according to claim 1, wherein the semiconductor laser light source has a structure embedded with a low material.

  The semiconductor laser light source according to claim 3 is the semiconductor laser light source according to claim 1 or 2, wherein the distributed feedback semiconductor laser part and the external resonator part are fabricated on the same semiconductor substrate. It is characterized by.

  The semiconductor laser light source according to claim 4 is the semiconductor laser light source according to any one of claims 1 to 3, wherein the external resonator section adjusts the phase of the feedback light for adjusting the phase of the feedback light. And a feedback light intensity adjustment region for adjusting the light intensity of the feedback light.

  The semiconductor laser light source according to claim 5 is the semiconductor laser light source according to any one of claims 1 to 4, wherein the distributed feedback semiconductor laser part and the external resonator part are hybrid-coupled. It is characterized by.

  A semiconductor laser light source according to a sixth aspect is the semiconductor laser light source according to any one of the first to fifth aspects, wherein an electrode of the resonator optical loss modulation region and an electrode of the distributed feedback semiconductor laser region are resistors. It is characterized by being electrically connected via.

  According to the present invention, by rapidly modulating the optical loss of the semiconductor laser resonator with an electrical signal, it is possible to suppress a rapid decrease in response sensitivity in the region of the resonance frequency or higher observed during direct injection current modulation. For example, it is possible to set the frequency of the photon resonance effect in a high frequency region of 60 GHz or more, and to provide a compact and high-speed voltage-controlled semiconductor laser light source having a response band approaching 100 Gb / s. it can.

It is a figure which shows the response speed of a single-piece | unit semiconductor laser. It is a figure which shows the structure of the semiconductor laser light source which concerns on Example 1 of this invention. It is a top view of the semiconductor laser light source which concerns on Example 1 of this invention. It is sectional drawing seen from the end surface direction of the semiconductor laser light source which concerns on Example 1 of this invention. It is a figure which shows the frequency response characteristic of the semiconductor laser light source which concerns on Example 1 of this invention. It is a figure which shows the top view of the semiconductor laser light source which concerns on Example 2 of this invention. It is a figure which shows the frequency response characteristic of the semiconductor laser light source which concerns on Example 2 of this invention. It is a figure which shows the eye pattern at the time of the operation | movement by the 80 Gb / sNRZ signal of the semiconductor laser light source which concerns on Example 2 of this invention. It is a figure which shows the structure of the semiconductor laser light source which concerns on Example 3 of this invention.

Example 1
FIG. 2 shows the structure of the semiconductor laser light source according to the first embodiment of the present invention. FIG. 2 shows a semiconductor laser light source 100 including an external resonator unit 105 and a semiconductor laser resonator unit 110. In the semiconductor laser light source 100 according to the present invention, a resonator optical loss modulation region in which the optical loss can be controlled at high speed by an electric signal in a configuration in which an external resonator for introducing a photon resonance effect is provided to the semiconductor laser resonator. Is provided in the semiconductor laser resonator, thereby realizing a high-speed response of the semiconductor laser light source by a simple method using loss modulation having a high affinity with the direct modulation laser used so far.

  As shown in FIG. 2, a semiconductor laser light source 100 according to the present invention includes a semiconductor laser resonator unit 110 including a DFB laser region 101 and a resonator light loss modulation region 102 disposed therebetween, a feedback light phase adjustment region 103, and And an external resonator unit 105 including a feedback light intensity adjustment region 104.

  The semiconductor laser resonator unit 110 and the external resonator unit 105 use a common cladding layer 119 and are monolithically integrated on a common semiconductor substrate 118. The DFB laser region 101, the resonator light loss modulation region 102, the feedback light phase adjustment region 103, and the feedback light intensity adjustment region 104 are electrically separated by an element separation groove 111 having a separation resistance of 1 MΩ or more provided between the regions. Has been. A common n-side electrode 112 is formed on the bottom surface of the semiconductor substrate 118. Further, a high reflection film 120 is formed on the end surface of the external resonator unit 105 where the semiconductor laser resonator unit 110 is not provided.

  In the semiconductor laser resonator unit 110, the DFB laser region 101 includes an active layer 113 formed between the semiconductor substrate 118 and the cladding layer 119, a diffraction grating 114 provided in the cladding layer 119, and the cladding layer 119. And a DFB laser current injection electrode 106. The resonator light loss modulation region 102 includes a resonator light absorption amount control layer 115 formed between the semiconductor substrate 118 and the cladding layer 119, a resonator light loss control electrode 107 provided on the cladding layer 119, including.

  In the external resonator unit 105, the feedback optical phase adjustment region 103 includes a feedback optical phase adjustment layer 116 formed between the semiconductor substrate 118 and the cladding layer 119, and a feedback optical phase adjustment electrode provided on the cladding layer 119. 108. The feedback light intensity adjustment region 104 includes a variable optical attenuator layer 117 formed between the semiconductor substrate 118 and the clad layer 119, and a feedback light intensity adjustment electrode 109 provided on the clad layer 119.

In the first embodiment, the length of each part is the length L _DFB of the DFB laser region 101 = 100 μm, the length L _{LM of} the resonator optical loss modulation region 102, and the length of the feedback optical phase adjustment region 103, respectively. L _PC = 100 μm and the length L _{LC of the} feedback light intensity adjustment region 104 was 150 μm.

  In the semiconductor laser resonator unit 110, an optical gain necessary for oscillation is generated by injecting current from the DFB laser current injection electrode 106 into the active layer 113 in the DFB laser region 101. The oscillation wavelength of the semiconductor laser light source 100 can be controlled by adjusting the pitch of the diffraction grating 114.

  The resonator light absorption control layer 115 in the resonator light loss modulation region 102 is formed of a semiconductor material having a composition having a short band wavelength slightly shorter than the active layer 113, and the resonator light loss control electrode 107. In this structure, the amount of light absorption can be controlled at high speed by applying a reverse bias voltage. By modulating the optical loss, the output light intensity or the oscillation light frequency of the semiconductor laser light source 100 is modulated.

  The oscillation light generated in the semiconductor laser resonator unit 110 and directed toward the external resonator unit 105 passes through the external resonator unit 105 and is reflected by the high reflection film 120 formed on the end face of the external resonator unit 105. Feedback is again made to the semiconductor laser resonator unit 110. At this time, the phase and intensity of the feedback light are controlled by the feedback light phase adjustment area 103 and the feedback light intensity adjustment area 104. In Example 1, carriers are injected into the feedback light phase adjustment layer 116 by applying a forward bias to the feedback light phase adjustment electrode 108 in the feedback light phase adjustment region 103, and the phase of the feedback light is controlled using the plasma effect. be able to. The variable optical attenuator layer 117 in the feedback light intensity adjustment region 104 is formed of a semiconductor material having a band short wavelength slightly shorter than the active layer 113, and is connected to the feedback light intensity adjustment electrode 109. By adjusting the amount of reverse bias voltage applied, the light absorption amount can be controlled, so that the feedback light intensity can be controlled.

  In the semiconductor laser resonator unit 110, the feedback light fed back to the semiconductor laser resonator unit 110 and the oscillation light generated in the DFB laser region 101 interact with each other to generate a photon resonance effect. By controlling the phase and intensity of the feedback light by the feedback light phase adjustment region 103 and the feedback light intensity adjustment region 104, the photon resonance effect frequency can be controlled.

  FIG. 3 is a top view for illustrating the surface electrode structure of the semiconductor laser light source according to the first embodiment of the present invention. As shown in FIG. 3, the DFB laser current injection electrode 106, the resonator light loss control electrode 107, the feedback light phase adjustment electrode 108, and the feedback light intensity adjustment electrode 109 are provided on the element surface of the semiconductor laser light source 100. Is formed.

  FIG. 4 is a cross-sectional view of the semiconductor laser light source according to the first embodiment of the present invention as viewed from the end surface direction. As shown in FIG. 4, the stripe width of the entire region, in particular, the resonator light loss modulation region 102 is 2 μm so that high speed loss modulation is possible by applying a high speed electric signal to the resonator light loss control electrode 107. The semiconductor substrate 118 was processed so that the embedded waveguide shape was embedded in the stripe side by a BCB buried layer 121 using a (benzocyclobutene: BCB) material. As a result, the pad capacitance of the electrodes in the respective regions on the element surface shown in FIG. 3, in particular, the resonator optical loss control electrode 107 was reduced.

In the semiconductor laser light source 100 according to Example 1, single mode oscillation at 1552 nm was confirmed when a bias current was applied only to the DFB laser region 101. The threshold current I _{th at} that time was 15 mA. By applying a reverse bias voltage to the resonator optical loss modulation region 102, an increase in threshold current can be confirmed, and the principle of the optical loss modulation operation can be confirmed. The threshold current when a reverse bias voltage of 1 V was applied to the resonator optical loss modulation region 102 was 22 mA.

In the semiconductor laser light source 100 according to the first embodiment, the total injection current into the DFB laser region 101 is set to 10 * I _th = 150 mA, and the resonator optical loss modulation region 102 is modulated with an RF signal, thereby evaluating the element response characteristics. Went. FIG. 5 shows the evaluation results of the frequency response band of the semiconductor laser light source according to Example 1 of the present invention. In FIG. 5, the reverse bias voltage V _R applied to the resonator optical loss modulation region 102 is V _R = 0.2 + 0.1 sin (2πft) [V], the modulation frequency f is 0 to 150 GHz, and I _PC is the feedback light. A bias current amount to the phase adjustment region 103 is shown, and V _LC denotes a reverse bias voltage to the feedback light intensity adjustment region 104. 5 shows the response characteristic of the semiconductor laser element when I _PC = 0 mA and V _LC = 5.0 V, and the characteristic 502 shows the semiconductor laser when I _PC = 15 mA and V _LC = 1.2 V. The response characteristic of the element is shown. The characteristic 503 shows the response characteristic of the semiconductor laser element when I _PC = 10 mA and V _LC = 1.0 V.

Here, 3 dB band in the characteristic 501 of FIG. 5 is about 50 GHz, by increasing the I _PC, it is possible to increase the photon resonance effect frequency.

Also, V _LC = 5.0V in the characteristic 501 is an example of the case taken to a very large value V _LC. When V _LC = 5.0V, the amount of light absorption in the feedback light intensity adjustment region 104 is large, and the feedback light cannot reach the resonator light loss modulation region 102. Therefore, V _LC is set larger than V _LC = 5.0V. However, the response characteristics are almost unchanged. By adjusting V _LC to be lower than V _LC = 5.0 V, it is possible to adjust the light absorption amount in the feedback light intensity adjustment region 104 so that a peak can easily appear.

  As shown in FIG. 5, in the characteristic 501, a 3 dB band can be obtained at a modulation frequency f = 50 GHz, and in the characteristics 502 and 503, since the photon resonance effect frequency is set higher, the 3 dB band at a higher modulation frequency. Can be obtained. Therefore, by performing loss modulation as in the present invention, the photon resonance effect frequency can be set higher than that of the conventional passive feedback laser, and a response speed higher than the conventional response speed of 30 to 35 GHz can be obtained. it can.

As shown in FIG. 5, by optimizing the bias current amount I _PC to the feedback light phase adjustment region 103 and the reverse bias voltage value V _LC to the feedback light intensity adjustment region 104, the response sensitivity is the response sensitivity of DC. It was confirmed that the 3 dB band, which is half the value, can be expanded to 130 GHz.

  In this embodiment, an embedded structure semiconductor laser light source in which stripes are embedded with BCB is shown. However, it is obvious that the semiconductor laser light source can be realized even with an element having an SI-InP embedded structure, or an element with a ridge structure or a high mesa structure. is there. In the present embodiment, the resonator optical loss modulation region 102 is disposed near the center of the semiconductor laser resonator unit 110. However, the resonator optical loss modulation region 102 is on the light output side of the DFB laser region 101. It goes without saying that the same effect can be obtained with a structure installed on the side where the external resonator unit 105 is integrated (the right side in FIG. 2) (the left side in FIG. 2). Further, in this embodiment, the element structure in which the semiconductor laser resonator unit 110 and the external resonator unit 105 are manufactured on the same semiconductor substrate has been described, but this region is described as an optical fiber, a glass waveguide, a SiN waveguide, etc. It is self-evident that the same effect can be realized also by manufacturing in the above manner and hybrid mounting on the semiconductor laser resonator unit 110. The same applies to the following embodiments.

(Example 2)
In the semiconductor laser light source 100 shown in the first embodiment, as shown in FIG. 5, there is a region with an abnormally high sensitivity in the region of 10 to 30 GHz of the frequency response characteristic. This is a sensitivity increase peak caused by the above, and becomes a factor that disturbs the waveform when operating with a digital signal. For this reason, it is necessary to reduce this strong sensitivity peak. The second embodiment realizes this sensitivity adjustment.

  FIG. 6 shows a top view of a semiconductor laser light source according to Embodiment 2 of the present invention. FIG. 6 shows a semiconductor laser light source in which two DFB laser current injection electrodes 106, a resonator light loss control electrode 107, a feedback light phase adjustment electrode 108, and a feedback light intensity adjustment electrode 109 are formed on the element surface. At 200, a semiconductor laser light source 200 provided with an electrode coupling resistor 122 that electrically couples the DFB laser current injection electrode 106 and the resonator light loss control electrode 107 is shown. The element structure other than the surface electrode structure in the second embodiment is the same as that in the first embodiment. As shown in FIG. 6, in the second embodiment, the DFB laser current injection electrode 106 and the resonator optical loss control electrode 107 are electrically coupled by an electrode coupling resistor 122 formed of a high-speed resistive thin film formed simultaneously during the electrode process. It has a structure.

  As described above, a forward voltage for injecting current is applied to the DFB laser current injection electrode 106, and a reverse bias voltage for controlling optical loss is applied to the resonator optical loss control electrode 107. By providing an electrode coupling resistor 122 between the DFB laser current injection electrode 106 and the resonator optical loss control electrode 107, the reverse bias voltage signal is applied to the resonator optical loss control electrode 107 in the DFB laser region 101. Part of the injected current flows into the power source (not shown) connected to the resonator optical loss control electrode 107 through the electrode coupling resistor 122, and as a result, the amount of current injected into the DFB laser region 101 controls the resonator optical loss control. It decreases by an amount proportional to the reverse bias voltage applied to the electrode 107. In other words, hybrid modulation in which intracavity loss modulation and injection current modulation are combined is possible. The ratio between the resonator loss modulation and the injection current modulation can be adjusted by the magnitude of the resistance value of the electrode coupling resistor 122.

  FIG. 7 shows the frequency response characteristics of the element when the electrode coupling resistor 122 is set to 200Ω. As shown in FIG. 7, the sensitivity increase peak observed in the region of 20 to 30 GHz in FIG. 5 described above is suppressed, and a relatively flat frequency response characteristic can be realized in the region of about −70 GHz from DC. .

  FIG. 8 shows an eye pattern during operation of the semiconductor laser light source according to the second embodiment of the present invention using an 80 Gb / s NRZ signal. By operating this device with a digital 80 Gb / s NRZ signal, a good eye opening eye pattern was observed as shown in FIG. 8, and the applicability of this device to an actual system could be confirmed.

  In the present embodiment, a structure in which the DFB laser current injection electrode 106 and the resonator optical loss control electrode 107 are electrically coupled by the electrode coupling resistor 122 is shown. However, the depth and width of the element isolation groove 111 are controlled. It is obvious that the same effect can be obtained by controlling the resistance value of the element isolation resistor.

(Example 3)
FIG. 9 shows the structure of a semiconductor laser light source according to Embodiment 3 of the present invention. FIG. 9 shows a semiconductor laser light source 300 including a semiconductor laser resonator unit 310 including a DFB laser region 101, a resonator light loss modulation region 102, and a feedback light phase adjustment region 103. In the third embodiment, a feedback optical phase adjustment region 103 is provided between the DFB laser region 101 and the resonator optical loss modulation region 102. The structures of the DFB laser region 101, the resonator optical loss modulation region 102, and the feedback optical phase adjustment region 103 are the same as those in the first embodiment. Each region is electrically isolated by the element isolation trench 111, and the isolation resistance is 1 MΩ or more.

  The semiconductor laser light source 300 according to the third embodiment has a structure in which the semiconductor laser resonator unit 310 is configured by the resonator optical loss modulation region 102 installed on the rear end face of the DFB laser region 101.

  In the semiconductor laser resonator unit 110, an optical gain necessary for oscillation is generated by injecting current from the DFB laser current injection electrode 106 into the active layer 113 in the DFB laser region 101. The oscillation wavelength of the semiconductor laser light source 100 can be controlled by adjusting the pitch of the diffraction grating 114.

  The resonator light absorption control layer 115 in the resonator light loss modulation region 102 is formed of a semiconductor material having a composition having a short band wavelength slightly shorter than the active layer 113, and the resonator light loss control electrode 107. In this structure, the amount of light absorption can be controlled at high speed by applying a reverse bias voltage. By modulating the optical loss of the oscillation light of the resonator, the output light intensity or the oscillation light frequency of the semiconductor laser light source 100 according to the present invention is modulated.

  The light in the right direction of the semiconductor laser resonator unit 310 is reflected by the highly reflective film 120 formed on the end face, and is fed back to the semiconductor laser resonator unit 310 again. At this time, the phase and intensity of the feedback light are controlled by the feedback light phase adjustment region 103. Here, carriers are injected into the feedback light phase adjustment layer 116 by applying a forward bias to the feedback light phase adjustment electrode 108 in the feedback light phase adjustment region 103, and the phase of the feedback light is controlled using the plasma effect.

The lengths of the respective portions are the length L _DFB of the DFB laser region 101 = 100 μm, the length L _{LM of} the resonator optical loss modulation region 102 = 50 μm, and the length L _{PC of the} feedback optical phase adjustment region 103 = 100 μm. . Further, similarly to Example 1, a buried waveguide shape was formed in which the stripe side was buried with a BCB buried layer 121 using a (benzocyclobutene: BCB) material.

In the semiconductor laser light source 300 according to Example 3, single mode oscillation at 1552 nm was confirmed when a bias current was applied only to the DFB laser region 101. The threshold current I _{th at} that time was 15 mA as in Example 1. By applying a reverse bias voltage to the resonator optical loss modulation region 102, an increase in threshold current can be confirmed, and the principle of the optical loss modulation operation can be confirmed. When a reverse bias voltage of 1 V was applied to the resonator optical loss modulation region 102, the threshold current was 22 mA.

In the semiconductor laser light source 300 according to the third embodiment, the total injection current into the DFB laser region 101 is set to 10 * I _th = 150 mA, and the resonator optical loss modulation region 102 is modulated with an RF signal, so that the element response characteristics are improved. Evaluation was performed. The evaluation result of the small signal response band when the reverse bias voltage V _R applied to the resonator optical loss modulation region 102 is V _R = 0.2 + 0.1 sin (2πft) [V] and the modulation frequency is 0 to 150 GHz. evaluated. It was confirmed that the 3 dB band where the response sensitivity is half of the value at DC can be expanded to 60 GHz.

Semiconductor laser light source 100, 200, 300
DFB laser region 101
Resonator optical loss modulation region 102
Feedback optical phase adjustment region 103
Feedback light intensity adjustment area 104
External resonator 105
DFB laser current injection electrode 106
Resonator optical loss control electrode 107
Feedback optical phase adjustment electrode 108
Feedback light intensity adjustment electrode 109
Semiconductor laser resonator unit 110
Element isolation groove 111
Common n-side electrode 112
Active layer 113
Diffraction grating 114
Resonator light absorption control layer 115
Feedback optical phase adjustment layer 116
Variable optical attenuator layer 117
Semiconductor substrate 118
Clad layer 119
High reflective film 120
BCB buried layer 121
Electrode coupling resistor 121

Claims (6)

A distributed feedback semiconductor laser section including a resonator optical loss modulation region and a distributed feedback semiconductor laser region;
An external resonator unit that reflects the oscillation light oscillated from the distributed feedback semiconductor laser unit and outputs the feedback light to the distributed feedback semiconductor laser unit;
With
The semiconductor laser light source, wherein the resonator optical loss modulation region performs loss modulation of the feedback light.   2. The semiconductor laser light source according to claim 1, wherein the semiconductor laser light source has a structure in which the resonator optical loss modulation region is embedded with a material having a dielectric constant lower than that of the resonator optical loss modulation region.   3. The semiconductor laser light source according to claim 1, wherein the distributed feedback semiconductor laser section and the external resonator section are fabricated on the same semiconductor substrate.   The external resonator unit includes a feedback light phase adjustment region for adjusting the phase of the feedback light and a feedback light intensity adjustment region for adjusting the light intensity of the feedback light. Item 4. The semiconductor laser light source according to any one of Items 1 to 3.   5. The semiconductor laser light source according to claim 1, wherein the distributed feedback semiconductor laser section and the external resonator section are hybrid-coupled.   6. The semiconductor laser light source according to claim 1, wherein an electrode of the resonator optical loss modulation region and an electrode of the distributed feedback semiconductor laser region are electrically connected via a resistor. .