JP7195156B2 - Semiconductor laser device - Google Patents

Description

The present application relates to a semiconductor laser device.

In an access system, which is an optical communication system between a repeater station and a user, an electro-absorption modulator (EAM) suitable for high-speed modulation and a distributed feedback semiconductor laser (DFB-LD) are used. EML (Electro-absorption Modulator integrated Laser), which is a semiconductor optical integrated device in which a semiconductor laser that outputs light of a single wavelength is integrated, is suitable.

In EML, it is necessary to use an EAM that has appropriate light absorption characteristics for the wavelength of the semiconductor laser. On the other hand, both the wavelength characteristics of EAM light absorption and the oscillation wavelength of a semiconductor laser are temperature dependent. Since the temperature dependence of the wavelength characteristics of the EAM differs from the temperature dependence of the oscillation wavelength of the semiconductor laser, when the temperature of the EML changes, not only the wavelength of light but also the extinction ratio, which is the modulation characteristic of the EAM, changes. modulation cannot be performed. Therefore, in general, a configuration is adopted in which the temperature is controlled by cooling the EML using a Peltier element or the like.

The power required for cooling and controlling the temperature often occupies a large proportion of the power of the entire semiconductor laser device. Realization is desired. For example, Patent Document 1 proposes uncooled operation by optimizing the difference between the laser oscillation wavelength λLD and the EAM absorption peak wavelength λEA, Δλ=λLD−λEA, and adjusting the EAM bias voltage for each temperature. there is

JP 2007-279406 A

However, in the technique described in Patent Document 1, in order to suppress the variation of the extinction ratio, it is necessary to adjust the EAM bias voltage corresponding to the temperature, and the adjustment procedure is complicated. Moreover, the temperature range in which uncooled operation can be realized is also limited.

The present application discloses a technique for solving the above problems, and an object thereof is to obtain a semiconductor laser device which is easy to adjust and has a wider temperature range in which uncooled operation can be realized.

The semiconductor laser device disclosed in the present application includes a plurality of DFB lasers having different oscillation wavelengths, a multiplexer that combines the outputs of the multiple DFB lasers, an EAM that modulates the light output from the multiplexer, and a temperature control device. a temperature detector to be measured; a laser selection controller that selects and switches a DFB laser to be operated from among a plurality of DFB lasers based on the temperature detected by the temperature detector ; are associated with an EAM bias controller for controlling the EAM bias voltage , the discrete temperature, the selected DFB laser for each temperature, the operating current value of the selected DFB laser, and the EAM bias voltage. a lookup table for storage, the laser selection controller selecting the DFB laser to be selected and the EAM bias controller setting the bias voltage of the EAM according to the information stored in the lookup table .

According to the semiconductor laser device disclosed in the present application, there is an effect that it is possible to obtain a semiconductor laser device that is easy to adjust and has a wider temperature range in which uncooled operation can be realized.

1 is a block diagram showing a schematic configuration of a semiconductor laser device according to Embodiment 1; FIG. 4 is a diagram for explaining the operation of the semiconductor laser device according to Embodiment 1; FIG. 4 is a flowchart for explaining an algorithm of operation of the semiconductor laser device according to Embodiment 1; FIG. 4 is a diagram for explaining the effect of the semiconductor laser device according to Embodiment 1; FIG. 3 is a block diagram showing a schematic configuration of a semiconductor laser device according to Embodiment 2; FIG. FIG. 11 is a diagram for explaining the operation of the semiconductor laser device according to Embodiment 2; FIG. 10 is a flowchart for explaining an algorithm of operation of the semiconductor laser device according to Embodiment 2; 3 is a block diagram showing a schematic configuration of a semiconductor laser device according to Embodiment 3; FIG. FIG. 10 is a diagram showing an example of a lookup table of the semiconductor laser device according to Embodiment 3; FIG. 10 is a flowchart for explaining an algorithm of the semiconductor laser device according to Embodiment 3; FIG. 11 is a diagram for explaining the operation of the semiconductor laser device according to Embodiment 3; 10 is a block diagram showing a schematic configuration of a semiconductor laser device according to Embodiment 4; FIG. FIG. 11 is a diagram for explaining the operation of the semiconductor laser device according to Embodiment 4; FIG. 12 is a flowchart for explaining an algorithm of operation of the semiconductor laser device according to Embodiment 4; FIG. 12 is a block diagram showing another schematic configuration of the semiconductor laser device according to Embodiment 4; FIG. 11 is a block diagram showing still another schematic configuration of a semiconductor laser device according to Embodiment 4; FIG. 12 is a diagram showing an example of a lookup table of the semiconductor laser device according to Embodiment 4;

Embodiment 1.
FIG. 1 is a schematic block diagram showing the configuration of a semiconductor laser device according to Embodiment 1. FIG. A semiconductor laser device 100 includes three semiconductor lasers LD1, LD2, and LD3 having different oscillation wavelengths, a multiplexer 104 for multiplexing their outputs, and one EAM (Electro-Absorption Modulator) 105 equipped with semiconductor light. An integrated device 10 is provided. Here, the semiconductor laser is a DFB laser (distributed feedback semiconductor laser). Furthermore, a temperature detector 107 for detecting the temperature of the semiconductor optical integrated device 10 and a laser selection controller 106 for selecting and operating one of the three semiconductor lasers according to the detected temperature Tc of the temperature detector 107 are provided. I have it. In FIG. 1, three-wavelength DFB lasers LD1, LD2 and LD3, a multiplexer 104 and one EAM 105 are monolithically integrated as a semiconductor optical integrated device 10. FIG. As the multiplexer 104, for example, a multiplexer based on MMI (Multi-Mode Interference) can be used. Alternatively, the multiplexer 104 may have a configuration in which a spatial optical system is used for multiplexing and the multiplexed light is incident on the EAM.

The operating temperature range of the semiconductor laser device 100 is, for example, the temperature Tc detected by the temperature detector 107=30 to 60.degree. The temperature detector 107 may be configured to measure the temperature of the semiconductor optical integrated device 10 on which the DFB laser and EAM are mounted. The semiconductor optical integrated device 10 is a very small device of mm order, and almost no temperature distribution occurs in the device. In addition, since the temperature inside the package containing the semiconductor optical integrated device 10 is almost equal to the temperature of the semiconductor optical integrated device 10, there is almost no temperature distribution inside the package. Therefore, the temperature can be measured anywhere within the package. Here, the temperature detector 107 has an accuracy of 5° C., that is, 30° C., 35° C., 40° C., . temperature, and values in between are not output. By the operation of the laser selection controller 106, the semiconductor laser LD1 is selected at 30.degree. C..ltoreq.Tc.ltoreq.35.degree. The semiconductor laser LD1 has an oscillation wavelength λLD1 of 1305 nm at 35°C. The semiconductor laser LD2 is selected at 40.degree. C..ltoreq.Tc.ltoreq.45.degree. C., and the oscillation wavelength .lambda.LD2 at 45.degree. The semiconductor laser LD3 is selected at 50.degree. C..ltoreq.Tc.ltoreq.60.degree. C., and the oscillation wavelength .lambda.LD3 at 55.degree.

The temperature dependence dλLD/dT of the oscillation wavelength of the DFB laser is 0.1 nm/°C. Here, when comparing the oscillation wavelengths of the respective DFB lasers at a temperature of 35° C., for example, LD1 is 1305 nm, LD2 is 1309 nm, and LD3 is 1313 nm. In this manner, three DFB lasers LD1, LD2, and LD3 having different oscillation wavelengths at the same temperature are mounted, and the DFB lasers are switched and operated according to the temperature range.

As described above, the temperature dependence dλLD/dT of the oscillation wavelength of the DFB laser is 0.1 nm/°C. On the other hand, the temperature dependence dλEA/dT of the absorption peak wavelength λEA at which the absorption of EAM light peaks is 0.5 nm/°C. 1250 nm, with an absorption layer. FIG. 2 shows the difference between the oscillation wavelength λLD of the laser and the absorption peak wavelength λEA of the EAM at this time, Δλ=λLD−λEA. For example, when Tc=40° C., the semiconductor laser LD2 is selected. Since the temperature detector outputs the detected temperature Tc in increments of 5°C, when Tc = 40°C, the actual temperature T is not necessarily 40°C. T=40° C.)=1309.5 nm. On the other hand, λEA (T=40° C.)=1242.5 nm and Δλ=67 nm. From FIG. 2, by selecting the semiconductor lasers LD1, LD2, and LD3 based on the detected temperature Tc, Δλ fluctuates in the range of 63 to 67 nm in the range of 30 to 60° C., and is suppressed to a sufficiently small amount of fluctuation. can be done.

FIG. 3 shows the algorithm for selecting and operating the lasers. Here, an example will be described in which the temperature detector 107 outputs the detected temperature Tc with an accuracy of 5° C., that is, in increments of 5° C., as described above. The laser selection controller 106 stores a lookup table as shown in FIG. 3 in which lasers to be selected for discrete temperatures of 5° C. are associated with current values to be applied to the lasers to be selected. ing. When the detected temperature Tc is transmitted from the temperature detector 107 to the laser selection controller 106 (step ST1), the laser corresponding to Tc and its current value are read from the stored lookup table (step ST2), and according to the read information. A semiconductor laser is selected, and the read current value is commanded to flow through the selected semiconductor laser (step ST3).

The timing of transmitting the detected temperature Tc from the temperature detector 107 to the laser selection controller 106 may be every constant period, or may be the timing when the detected temperature Tc changes. For example, when the detected temperature Tc detected by the temperature detector 107 changes from 35° C. to 40° C., Tc is transmitted to the laser selection controller. The laser selection controller 106 selects the DFB laser LD2 corresponding to 40.degree. When the detected temperature Tc changes from 40.degree. C. to 45.degree. When the detected temperature Tc rises from 45° C. to 50° C., the DFB laser LD3 is selected, and the DFB laser LD3 is commanded to pass a current of 70 mA. When the detected temperature Tc drops from 45° C. and changes to 40° C., an instruction is given to change the current value flowing through the DFB laser LD2 from 65 mA to 60 mA.

As described above, the temperature change rate of the absorption peak wavelength of the EAM is 0.5 nm/°C, and the temperature change rate of the oscillation wavelength of the DFB laser is 0.1 nm/°C. Although the oscillation wavelength of the DFB laser changes according to the temperature dependence of the refractive index of the diffraction grating, such a difference occurs because the EAM absorption peak wavelength changes according to the temperature dependence of the semiconductor bandgap. For this reason, if the semiconductor laser device has only the DFB laser LD2 with the characteristics indicated by the dotted line in FIG. , resulting in a large amount of variation. The value of Δλ changes with temperature changes, and Δλ changes by 12 nm between 30°C and 60°C. In the case of the first embodiment indicated by the solid line, the difference between the maximum value and the minimum value of Δλ is 4 nm by switching the DFB laser in three temperature ranges. The EAM performance depends on this Δλ. FIG. 4 shows the Δλ dependence of the extinction ratio when modulated by EAM. The extinction ratio change is about 7 dB when Δλ changes from 59 nm to 71 nm by 12 nm, but the extinction ratio change is about 2 dB when Δλ changes from 63 nm to 67 nm by 4 nm. According to the first embodiment, fluctuations in the extinction ratio can be suppressed without temperature control of the semiconductor optical integrated device using a Peltier element or the like, and without adjusting the bias voltage of the EAM according to the temperature.

In the example of FIG. 3, the temperature is read with an accuracy of 5°C, and the laser to be selected and the current value are specified. It can also be defined as a function. If the accuracy of the detected temperature is increased, it is conceivable that the operation will become unstable near the threshold temperature at which the selected laser or current value is changed. In this case, a stable operation can be ensured by providing a so-called hysteresis operation in which the laser switching temperature differs between when the temperature rises and when it falls. For example, if the lookup table is specified with an accuracy of 1°C, switching from LD1 to LD2 is performed when the temperature rises to 41°C, and switching from LD2 to LD1 is performed when the temperature rises to 41°C. This method is performed when the temperature drops and 39°C is detected.

When the lookup table is specified for each discrete temperature and the accuracy of the temperature detector 107 is the same as the discrete temperature interval, that is, when the lookup table is specified for each 5° C., temperature detection is performed. If the accuracy of the detector 107 is set to 5° C., or if the accuracy of the temperature detector 107 is set to 1° C. when the lookup table is specified for every 1° C., the operation automatically becomes a hysteresis operation. For example, if the lookup table is specified for each 1°C, when the temperature rises, when the detected temperature Tc changes from 39°C to 40°C, the selection of the DFB laser and the set value of the current value corresponding to 40°C are performed. When the temperature drops, when Tc changes from 40.degree. C. to 39.degree. This operation is a hysteresis operation. Furthermore, when the detected temperature changes to 40° C. during temperature rise, the DFB current value is increased as shown in the lookup table of FIG. On the other hand, when the temperature drops to 35° C., the DFB current value is decreased, so the temperature of the semiconductor optical integrated device changes further. This characteristic also emphasizes hysteresis operation and realizes stable operation.

The accuracy of the detected temperature Tc output by the temperature detector 107 is not the same as the value of the discrete temperature interval stored in the lookup table as described above, and even if the accuracy is equal to or greater than the value of this interval. good. That is, the interval between the values of the detected temperature Tc output by the temperature detector 107 may be equal to or less than the discrete temperature intervals stored in the lookup table. For example, the accuracy of the temperature detector 107 is 0.1° C., that is, the detected temperature Tc of the temperature detector 107 is output at intervals of 0.1° C., and the lookup table is set every 5° C. as shown in FIG. It may be a stored configuration. In this case, for example, when 30.0° C.≦Tc≦34.9° C., the laser selection controller 106 selects the DFB laser LD1 and commands the DFB laser LD1 to flow a current value of 50 mA. When Tc changes from 34.9° C. to 35.0° C., laser selection controller 106 commands the current value of DFB laser LD1 to be changed to 55 mA. At 35.0° C.≦Tc≦39.9° C., the laser selection controller 106 selects the DFB laser LD1 and commands the DFB laser LD1 to flow a current value of 55 mA. When Tc changes from 39.9° C. to 40.0° C., the laser selection controller 106 selects the DFB laser LD2 and commands the DFB laser LD2 to flow a current value of 60 mA. At 40.0° C.≦Tc≦44.9° C., the laser selection controller 106 selects the DFB laser LD2 and commands the DFB laser LD2 to flow a current value of 60 mA. When the temperature drops and Tc changes from 40.0° C. to 39.9° C., the DFB laser LD1 is selected, and the laser selection controller 106 commands the DFB laser LD1 to pass a current of 55 mA. As described above, when the accuracy of the temperature detected by the temperature detector 107 is high, the hysteresis operation described above is particularly effective. For example, when the temperature rises, the selection of the DFB laser is switched from LD1 to LD2 when Tc rises from 39.9°C to 40.0°C. It is preferable to perform a hysteresis operation such as switching from LD2 to LD1.

In the above, an example in which DFB lasers with three different wavelengths are selected has been described. The operating temperature range can be extended.

As described above, according to the semiconductor laser device according to the first embodiment, it is possible to operate in a wide temperature range without having a temperature control function. No need for bias adjustment. Furthermore, since only semiconductor lasers with different wavelengths are selected, the configuration of the laser selection controller 106 is also simple. As shown in FIG. 2, for example, when only the DFB laser LD2 and EAM are provided, Δλ varies over a wide range of 59 nm to 71 nm when the temperature changes between 30 and 60°C. When the EAM is used with a fixed bias voltage, the extinction ratio fluctuation amount at 30 to 60° C. is 7 dB if it does not have a semiconductor laser selection function. The relative fluctuation amount can be suppressed to 2 dB.

Embodiment 2.
FIG. 5 is a schematic block diagram showing the configuration of the semiconductor laser device according to the second embodiment. A semiconductor laser device 100 is a semiconductor optical integrated device equipped with three semiconductor lasers (here, DFB lasers) having different oscillation wavelengths LD1, LD2, and LD3, a multiplexer 104 for multiplexing them, and one EAM 105. 10 are provided. Further, a temperature detector 107 such as a thermistor for detecting the temperature of the semiconductor optical integrated device 10, and a laser selection controller that selects and operates one of the three semiconductor lasers according to the detected temperature Tc of the temperature detector 107. 106 and an EAM bias controller 108 that adjusts the EAM bias voltage according to the temperature Tc detected by the temperature detector 107 .

Hereinafter, the case where the accuracy of the temperature Tc detected by the temperature detector 107 is 5.degree. C. and the lookup table is specified for each discrete temperature of 5.degree. The operating temperature range of this semiconductor laser device 100 is Tc=-40 to 90.degree. The operation of the laser selection controller 106 selects the semiconductor laser LD1 at -40°C ≤ Tc ≤ 0°C. The oscillation wavelength λLD1 of the semiconductor laser LD1 at a temperature of -20°C is 1287.5 nm. The semiconductor laser LD2 is selected when 5°C ≤ Tc ≤ 45°C. The oscillation wavelength λLD2 of the semiconductor laser LD2 at a temperature of 25° C. is 1310 nm. The semiconductor laser LD3 is selected when 50°C ≤ Tc ≤ 90°C. The oscillation wavelength λLD3 of the semiconductor laser LD3 at a temperature of 70° C. is 1323 nm. The temperature dependence dλLD/dT of the oscillation wavelength λLD of the DFB laser is 0.1 nm/°C, the temperature dependence dλEA/dT of the absorption peak wavelength λEA of the EAM is 0.5 nm/°C, and the bias voltage Vc dependence is 20 nm. /V. FIG. 6 shows the temperature dependence of λEA for five Vc values. The median value of Vc shown in FIG. = 1267.5 nm. For example, when Tc=25° C., the semiconductor laser LD2 is selected according to the lookup table shown in FIG. . λ EA (T=25° C., Vc=−1.2 V)=1245 nm and Δλ=65 nm. By selecting a laser and setting Vc as shown in the lookup table of FIG. 7 based on the detected temperature Tc, the range of Tc=−40 to 90° C. and Δλ fluctuates in the range of 63 to 65 nm. , the effective Δλ temperature variation can be suppressed within a narrow range.

FIG. 7 also shows the algorithm of operation when selecting a laser. Detected temperature Tc is transmitted from temperature detector 107 to laser selection controller 106 and EAM bias controller 108 (step ST21). As shown in FIG. 7, the laser selection controller 106 selects a DFB laser corresponding to the detected temperature Tc from a lookup table in which the DFB laser to be selected for each discrete temperature and the current value to be set are stored in advance. The current values to be set for the laser and the DFB laser are read (step ST22), and the selected DFB laser is commanded to flow the specified current value (step ST23). The EAM bias controller 108 also reads the bias voltage Vc corresponding to the detected temperature Tc from the lookup table (step ST24), and instructs the EAM to apply a predetermined bias voltage Vc (step ST25). With such a control method, it is possible to suppress the fluctuation amount of Δλ to a sufficiently small range.

As described above, in the second embodiment, not only the semiconductor laser is selected and switched, but also the set value of the EAM bias voltage Vc is changed for each detected temperature, thereby only selecting the semiconductor laser according to the detected temperature. The amount of variation in Δλ due to temperature is suppressed more than in the first embodiment, and operation in a wider temperature range can be made possible.

Embodiment 3.
FIG. 8 is a schematic block diagram showing the configuration of a semiconductor laser device 100 according to Embodiment 3. As shown in FIG. A semiconductor laser device 100 is a semiconductor optical integrated device equipped with three semiconductor lasers (here, DFB lasers) having different oscillation wavelengths LD1, LD2, and LD3, a multiplexer 104 for multiplexing them, and one EAM 105. 10 are provided. Furthermore, a photocurrent detector 109 for detecting the photocurrent flowing when the EAM 105 absorbs light, and one of the three semiconductor lasers is selected and operated by the photocurrent detected by the photocurrent detector 109. A laser selection controller 106 is provided.

In advance, the temperature and the value of the EAM photocurrent when each laser is operated are measured. Here, since the response speed of the photocurrent detection circuit is sufficiently slower than the signal modulation speed, the photocurrent value output by the photocurrent detector 109 is not affected by the EAM modulation rate. Determine the range of photocurrent values, i.e., the upper and lower thresholds, over the appropriate operating temperature range, and select the laser and its current value so that the photocurrent values are between the upper and lower thresholds. , a table as shown in FIG. In FIG. 9, the photocurrent values are shown as absolute values. Also, the temperature range in the table of FIG. 9 is for reference only and is not necessarily required in the lookup table.

FIG. 10 shows the flow of operation. First, the photocurrent value is read (step ST31), and if the photocurrent value (absolute value) exceeds the upper limit threshold (YES in step ST32), the DFB laser that is on the higher temperature side than the DFB laser that has been operated up to that point is selected. If the photocurrent value exceeds the lower limit threshold (YES in step ST32), the DFB laser is switched to the lower temperature side and operated (step ST35). Otherwise, the DFB laser to be selected remains unchanged and the setting is not changed (step ST36). The routine described above is performed, for example, at regular intervals. For example, assume that a current of 60 mA is flowing through the semiconductor laser LD2 as the laser initial state. Photocurrent detector 109 sends the photocurrent value to laser selection controller 106, which laser selection controller 106 reads. When the value exceeds 5.4 mA, the laser selection controller 106 determines that the photocurrent upper threshold has been exceeded, switches to the high temperature side laser, and operates the semiconductor laser LD3 by supplying 70 mA.

Alternatively, when the photocurrent detection value exceeds the upper threshold value or the lower threshold value stored in the lookup table, the photocurrent detector 109 notifies the laser selection controller 106 of the information that the upper threshold value or the lower threshold value has been exceeded. The DFB laser to be operated may be switched by the laser selection controller 106 .

In the third embodiment, instead of detecting the temperature, the temperature dependence of the EAM photocurrent is used to switch the laser. FIG. 11 shows an example of photocurrent temperature dependence of the semiconductor lasers LD1, LD2, and LD3. As the temperature increases, the effective Δλ decreases, more light is absorbed, and the photocurrent value (absolute value) increases. If this value reaches a lookup table threshold, switch to the adjacent semiconductor laser.

Here, the configuration for only selecting the semiconductor laser has been described, but a configuration for changing the bias voltage of the EAM based on the photocurrent detection value may be added as described in the second embodiment. can.

According to the third embodiment, as compared with the first embodiment, there is no need for an accessory such as a temperature detector, so the semiconductor laser device can be further miniaturized.

Embodiment 4.
FIG. 12 is a schematic block diagram showing the configuration of a semiconductor laser device 200 according to Embodiment 4. As shown in FIG. Here, a DBR (Distributed Bragg Reflector) laser is used as the semiconductor laser 120 . A DBR laser 120 and an EAM 105 are mounted on the semiconductor optical integrated device 20 . The DBR laser 120 has a distributed reflection region 121 and a gain region 122 as a configuration. When the current injected into the distributed reflection region 121 is changed, the oscillation wavelength of the DBR laser 120 is changed. Therefore, the DBR controller 123 changes the injection current of the distributed reflection region 121 according to the detected temperature Tc of the temperature detector 107 to change the oscillation wavelength of the DBR laser 120, thereby changing the oscillation wavelength λDBR of the DBR laser 120 and the EAM 105. The difference in absorption peak wavelength λEA, Δλ=λDBR−λEA, can be suppressed.

Hereinafter, the case where the accuracy of the temperature Tc detected by the temperature detector 107 is 5° C. will be described as in the first embodiment. The operating temperature range of the semiconductor laser device 200 is, for example, Tc=30 to 60.degree. Due to the operation of the DBR controller 123, 20 mA is selected as the current of the distributed reflection region 121 at 30° C.≦Tc≦35° C. FIG. The oscillation wavelength λDBR of the DBR laser 120 at a temperature of 35°C is 1305 nm. At 40° C.≦Tc≦45° C., 5 mA is selected as the current of the distributed reflection region 121 . The oscillation wavelength λDBR at a temperature of 45°C is 1310 nm. At 50° C.≦Tc≦60° C., 0 mA is selected as the current of the distributed reflection region 121 . The oscillation wavelength λDBR at a temperature of 55°C is 1315 nm. The temperature dependence dλEA/dT of the absorption peak wavelength λEA of EAM105 is 0.5 nm, λEA (T = 35°C) = 1240nm, λEA (T = 45°C) = 1245nm, λEA (T = 55°C) = 1250nm, It has an absorption layer such that Δλ at this time is shown in FIG. For example, when Tc=40° C., a current of 5 mA is selected for the distributed reflection region 121 . λDBR (T=40° C.)=1309.5 nm. On the other hand, λEA (T=40° C.)=1242.5 nm and Δλ=67 nm. From FIG. 13, it can be seen that Δλ fluctuates in the range of 63 to 67 nm in the range of 30 to 60° C. and can be suppressed to a sufficiently small fluctuation range.

FIG. 14 shows an example of an operation algorithm and a lookup table. Detected temperature Tc of temperature detector 107 is transmitted to DBR controller 123 (step ST41). The DBR controller 123 reads the distributed reflection area current value corresponding to the temperature from a preset lookup table (step ST42), and sets the current value of the distributed reflection area 121 (step ST43). For example, if the detected temperature Tc is 35° C., the current value of the distributed reflection area 121 is set to 20 mA. When Tc reaches 40° C., the current value of the distributed reflection region 121 is set to 5 mA. By changing the wavelength of the DBF laser corresponding to the detected temperature Tc by such a control method, it is possible to suppress the fluctuation amount of Δλ to a sufficiently small range even if the temperature changes.

Furthermore, as described in the second embodiment, as shown in FIG. 15, an EAM bias controller 108 that changes the EAM bias voltage in accordance with the detected temperature may be provided. Thereby, the operable temperature range can be further widened.

Further, as described in the third embodiment, as shown in FIG. 16, instead of detecting temperature, the value of the photocurrent detected by the photocurrent detector 109 is used by the DBR controller 123 to detect the distributed reflection region. It is also possible to adopt a configuration in which the current value of is switched. For example, a lookup table as shown in FIG. 17 is stored, and when the photocurrent value exceeds the lower limit threshold, the distributed reflection area current value is changed to a value on the lower temperature side, and the photocurrent value exceeds the upper limit threshold. The DBR controller 123 may perform control so that the distributed reflection region current value is changed to a value on the high temperature side when it exceeds.

As described above, in a semiconductor laser device having the semiconductor optical integrated device 20 composed of a DBR laser and an EAM, by adjusting the current value of the distributed reflection region of the DBR laser based on the temperature or photocurrent value, A semiconductor laser device capable of uncooled operation in a wide temperature range can be obtained.

Although various exemplary embodiments and examples are described herein, various features, aspects, and functions described in one or more embodiments may vary from particular embodiment to embodiment. The embodiments are applicable singly or in various combinations without being limited to the application. Accordingly, numerous variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, modification, addition or omission of at least one component, extraction of at least one component, and combination with components of other embodiments shall be included.

10, 20 semiconductor optical integrated device, 100, 200 semiconductor laser device, 104 multiplexer, 105 EAM, 106 laser selection controller, 107 temperature detector, 108 EAM bias controller, 109 photocurrent detector, 120 semiconductor laser ( DBR laser), 121 distributed reflection region, 122 gain region, 123 DBR controller, LD1, LD2, LD3 semiconductor laser (DFB laser)

Claims (2)

a plurality of DFB lasers with different oscillation wavelengths;
a combiner for combining the outputs of the plurality of DFB lasers;
an EAM that modulates the light output from the multiplexer;
a temperature sensor for measuring temperature;
a laser selection controller that selects and switches a DFB laser to be operated from among the plurality of DFB lasers based on the temperature detected by the temperature detector ;
an EAM bias controller that controls the bias voltage of the EAM based on the temperature detected by the temperature detector ;
a lookup table that stores discrete temperatures in association with the DFB laser selected for each temperature, the operating current value of the selected DFB laser, and the bias voltage of the EAM ;
The laser selection controller selects the DFB laser of choice and the EAM bias controller sets the bias voltage of the EAM according to information stored in the lookup table.
A semiconductor laser device characterized by: 2. The semiconductor laser device according to claim 1 , wherein the accuracy of the temperature detected by said temperature detector is equal to or greater than the discrete temperature intervals stored in said lookup table.

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