JP7575288B2 - Tunable wavelength laser device and method for controlling the same - Google Patents

Description

The present invention relates to a wavelength tunable laser device and a method for controlling a wavelength tunable laser device.

Conventionally, a tunable laser device has been known that has a tunable light source that outputs a laser beam with a variable wavelength and a semiconductor optical amplifier that optically amplifies the laser beam (for example, Patent Document 1).

JP 2019-140308 A

In this type of tunable laser device, if the operation of the tunable light source stops while the semiconductor optical amplifier is operating, there is a risk that laser light with an abnormal wavelength will be output without wavelength control.

Therefore, one of the objectives of the present invention is to provide an improved new wavelength tunable laser device, a control method for a wavelength tunable laser device, and a program that can suppress the output of laser light with abnormal wavelengths, for example.

The tunable laser device of the present invention is, for example, a tunable laser device, and includes a tunable light source that outputs a laser light whose wavelength can be changed, a semiconductor optical amplifier that optically amplifies the laser light, and at least a controller that can be controlled to stop the operation of the semiconductor optical amplifier and can be controlled to reset the tunable laser device, and when the operation of the tunable light source is stopped, the controller stops the operation of the semiconductor optical amplifier before the operation of the tunable light source is stopped.

The tunable laser device may include a detection circuit that outputs a detection signal when it detects a drop in the power supply voltage of the tunable laser device that satisfies a predetermined condition, and a first delay circuit that delays the drop in the power supply voltage input to the controller, and the controller may have a first stop control unit that stops the operation of the semiconductor optical amplifier in response to the input of the detection signal.

In the tunable laser device, the controller may have a first reset control unit that resets the tunable laser device if the tunable laser device does not shut down due to a drop in the power supply voltage after the operation of the semiconductor optical amplifier is stopped under the control of the first stop control unit.

In the tunable laser device, the first reset control unit may reset the tunable laser device when a predetermined time has elapsed after the detection signal is input.

The tunable laser device may include a first filter circuit that dulls the waveform of the power supply voltage input to the detection circuit.

The tunable laser device may include a second delay circuit that delays a reset signal input to the controller, and the controller may have a first port to which the reset signal is input via the second delay circuit, a second port to which the reset signal is input without passing through the second delay circuit, a second stop control unit that stops the operation of the semiconductor optical amplifier in response to the reset signal input via the second port, and a second reset control unit that resets the tunable laser device in response to the reset signal input via the first port.

In the tunable laser device, the controller may have a third reset control unit that resets the tunable laser device if the tunable laser device is not reset by the second reset control unit after the operation of the semiconductor optical amplifier is stopped under the control of the second stop control unit.

In the tunable laser device, the third reset control unit may reset the tunable laser device when a predetermined time has elapsed after the reset signal is input.

The tunable laser device may include a second filter circuit that dulls the waveform of the reset signal input to the second port.

In the tunable laser device, the controller may have a third stop control unit that stops the operation of the semiconductor optical amplifier when a reset instruction signal is received by communication, and a fourth reset control unit that resets the tunable laser device after the operation of the semiconductor optical amplifier is stopped under the control of the third stop control unit.

In the method for controlling a tunable laser device of the present invention, for example, a tunable light source having a semiconductor optical amplifier for optically amplifying laser light and outputting laser light whose wavelength can be changed, and a controller that can at least be controlled to stop the operation of the semiconductor optical amplifier and to reset the tunable laser device, a computer operating as the controller stops the operation of the semiconductor optical amplifier before the operation of the tunable light source stops when the operation of the tunable light source stops.

The program of the present invention is, for example, a program that causes a computer to operate as the controller of a tunable laser device that includes a tunable light source that has a semiconductor optical amplifier that optically amplifies laser light and outputs laser light whose wavelength can be changed, and a controller that is at least capable of controlling the semiconductor optical amplifier to stop operating and is also capable of controlling the tunable laser device to reset, and when the operation of the tunable light source is stopped, the controller stops the operation of the semiconductor optical amplifier before the operation of the tunable light source is stopped.

The present invention provides an improved new wavelength tunable laser device, a control method for a wavelength tunable laser device, and a program that can suppress the output of laser light with abnormal wavelengths.

FIG. 1 is an exemplary schematic configuration diagram of a wavelength tunable laser device according to the first embodiment. FIG. 2 is an exemplary block diagram of a control device of the wavelength tunable laser device according to the first embodiment. FIG. 3 is a flowchart showing an example of a processing procedure performed by the control device when the power supply voltage drops in the wavelength tunable laser device of the first embodiment. FIG. 4 is a timing chart showing an example of the output state and operation state of signals of each part when the power supply voltage drops in the wavelength tunable laser device of the first embodiment. FIG. 5 is a timing chart showing another example of the output states and operation states of the signals of the various parts when the power supply voltage drops in the wavelength tunable laser device of the first embodiment. FIG. 6 is a flowchart showing an example of a processing procedure by the control device when a reset signal is input in the wavelength tunable laser device of the first embodiment. FIG. 7 is a timing chart showing an example of the output states and operation states of signals in each section when a reset signal is input in the wavelength tunable laser device of the first embodiment. FIG. 8 is a timing chart showing another example of the output states and operation states of the signals of the various parts when a reset signal is input in the wavelength tunable laser device of the first embodiment. FIG. 9 is a flowchart showing an example of a processing procedure performed by the control device when a reset command is received in the wavelength tunable laser device of the first embodiment. FIG. 10 is an exemplary schematic configuration diagram of a wavelength tunable laser device according to the second embodiment. FIG. 11 is an exemplary schematic configuration diagram of a wavelength tunable laser device according to the third embodiment.

Below, exemplary embodiments of the present invention are disclosed. The configurations of the embodiments shown below, and the actions and results (effects) brought about by said configurations, are merely examples. The present invention can also be realized with configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

The multiple embodiments described below have similar configurations. Therefore, according to the configuration of each embodiment, similar actions and effects based on the similar configurations can be obtained. Furthermore, below, the similar configurations are given the same reference numerals, and duplicate explanations may be omitted.

In this specification, ordinal numbers are used for convenience to distinguish between circuits, control units, etc., and do not indicate priority or order.

[First embodiment]
Fig. 1 is a schematic diagram of a tunable laser device 1. As shown in Fig. 1, the tunable laser device 1 includes a light source device 10 and a control device 100. The light source device 10 is an example of a tunable light source. The light source device 10 also includes a semiconductor optical amplifier 70. Note that a portion of the light source device 10 excluding the semiconductor optical amplifier 70 may be referred to as a tunable light source.

[Tunable wavelength light source]
In the present embodiment, as an example, the light source device 10 includes an SG-DBR section 20 (SG-DBR: sampled-grating distributed Bragg reflector), a phase adjustment section 30, a gain section 40, a connection section 50, a ring resonator filter 60, and a semiconductor optical amplifier 70. The light source device 10 has a wavelength-tunable laser resonator that utilizes the Vernier effect, and constitutes a wavelength-tunable light source that outputs laser light with a variable wavelength.

The light source device 10 is configured to have predetermined functions such as a waveguide layer and an active layer (not shown) in, for example, a mesa 12 provided on a semiconductor laminate substrate 11.

The SG-DBR section 20, the phase adjustment section 30, the gain section 40, the connection section 50, the ring resonator filter 60, and the semiconductor optical amplifier 70 are made of, for example, an InP-based semiconductor material.

The SG-DBR section 20 has a waveguide that includes a distributed Bragg reflector sampled grating (SG-DBR) configuration. The SG-DBR section 20 constitutes one of the reflecting sections of the laser resonator.

The gain section 40 has an active layer. The gain section 40 is provided with a pair of electrodes (not shown) spaced apart from each other. By applying a voltage to the pair of electrodes, a current flows through the active layer, resulting in an optical amplification effect. This causes laser oscillation.

The connection section 50 is branched at a branching section, such as a 1x2 MMI coupler, optically connected to the gain section 40, and has two mesas 12 that are bent in a plan view in opposite directions in the Z direction. The waveguide layer of each mesa 12 is optically connected at the coupling section C to the waveguide layer of the oval or annular mesa 12 of the ring resonator filter 60 by a 2x2 MMI coupler or the like.

The ring resonator filter 60, in combination with the connection section 50, has reflection spectrum characteristics with comb-shaped peaks with a different period from that of the SG-DBR section 20, and constitutes the other reflection section of the laser resonator.

The semiconductor optical amplifier 70 has an active layer. The semiconductor optical amplifier 70 is provided with a pair of electrodes (not shown) spaced apart from each other, and applying a voltage to the pair of electrodes causes a current to flow through the active layer, resulting in an optical amplification effect.

In the above configuration, the active layer has a multiple quantum well (MQW) structure made of, for example, GaInAsP-based semiconductor material or AlGaInAs-based semiconductor material. The passive waveguide is made of, for example, an i-type GaInAsP-based semiconductor material with a band gap wavelength of 1300 nm. The SG-DBR-configured waveguide is made of, for example, GaInAsP-based semiconductor material or AlGaInAs-based semiconductor material, and the portions with different refractive indices are periodically arranged to form a diffraction grating.

The SG-DBR section 20, the phase adjustment section 30, and the ring resonator filter 60 each have a heater layer (not shown). The heater layer is a so-called resistive heating element, and generates heat in response to the supply of current. The heater layer is provided with wiring structures such as electrodes and conductor layers for supplying current.

The SG-DBR section 20 has comb-shaped reflection peaks with periodic frequency intervals that correspond to the inverse of the period of the diffraction grating. The SG-DBR section 20 and the ring resonator filter 60 have different periods, and the configuration allows for coarse tuning of the frequency of the laser light by a method known as the Vernier type. When the heater layer heats the SG-DBR section 20, the refractive index of the SG-DBR section 20 changes, and the comb-shaped reflection peaks shift in the frequency axis direction. Similarly, when the heater layer heats the ring resonator filter 60, the refractive index of the ring resonator filter 60 changes, and the comb-shaped reflection peaks shift in the frequency axis direction.

In addition, by heating the heater layer (not shown) of the phase adjustment unit 30, the refractive index of the waveguide layer can be changed, thereby adjusting the optical length of the laser resonator. By adjusting the optical length of the laser resonator, the frequency of the resonator mode (cavity mode) can be shifted in the frequency axis direction while being finely adjusted. Fine adjustment of the resonator mode makes it possible to select the resonator mode in laser oscillation and to change the frequency within a small range. In this embodiment, the phase adjustment unit 30 is provided in a part of the connection unit 50 as an example, but the position at which the phase adjustment unit 30 is provided is not limited to the connection unit 50.

In the light source device 10 having the semiconductor optical amplifier 70 as described above, when the operation of the semiconductor optical amplifier 70 is stopped, even if the tunable light source is operated, the laser light output from the tunable light source is absorbed by the semiconductor optical amplifier 70 and is not output from the light source device 10. However, when the operation of the tunable light source is stopped while the semiconductor optical amplifier 70 is operating, there is a risk that laser light of an abnormal wavelength will be output in an uncontrolled state. Therefore, in this embodiment, the control device 100 that controls the operation of the light source device 10 has a function of suppressing the output of laser light of such an abnormal wavelength.

[Control device]
2 is a block diagram showing a schematic configuration of the control device 100A (100). As shown in FIG. 2, the control device 100A has a controller 110, a main memory unit 120, and an auxiliary memory unit .

The controller 110 has at least the function of stopping the operation of the semiconductor optical amplifier 70 and the function of resetting the wavelength tunable laser device 1.

The controller 110 is, for example, a processor (circuit) such as a CPU (central processing unit). The main memory unit 120 is, for example, a RAM (random access memory) or a ROM (read only memory). The auxiliary memory device 130 is, for example, a non-volatile memory device such as an SSD (solid state drive) or an HDD (hard disk drive).

The controller 110 operates as the first stop control unit 110a, the second stop control unit 110b, the third stop control unit 110c, the communication control unit 110d, the first reset control unit 110e, the second reset control unit 110f, the third reset control unit 110g, and the fourth reset control unit 110h by reading the programs stored in the main memory unit 120 and the auxiliary storage unit 130 and executing each process. The programs may be provided in a computer-readable recording medium in an installable or executable format. The recording medium may also be called a program product. Information such as values, tables, maps, etc. used in the program and the arithmetic processing by the processor may be stored in the main memory unit 120 or the auxiliary storage unit 130 in advance, or may be stored in a memory unit of a computer connected to a communication network and downloaded via the communication network to the auxiliary storage unit 130. The auxiliary storage unit 130 stores data written by the processor. The arithmetic processing by the controller 110 may also be performed at least in part by hardware. In this case, the controller 110 may include, for example, an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Furthermore, the control device 100A has a first delay circuit 211, a detection circuit 212, and a second delay circuit 221.

The first delay circuit 211 is a delay circuit that delays the drop in the power supply voltage input to the controller 110.

The detection circuit 212 outputs a detection signal when it detects a drop in the power supply voltage of the wavelength tunable laser device 1 that satisfies a predetermined condition. The detection circuit 212 is configured as, for example, an integrated circuit.

The second delay circuit 221 delays the reset signal input to the controller 110.

The controller 110 has four ports P1 to P4.

The power supply voltage delayed by the first delay circuit 211 is input to port P1.

The detection signal output from the detection circuit 212 is input to port P2.

A reset signal that is delayed by the second delay circuit 221 is input to port P3 via the second delay circuit 221. The reset signal is, for example, a signal that goes from a predetermined high-level potential to a predetermined low-level potential and then goes back to the predetermined high-level potential. Port P3 is an example of a first port.

In addition, the reset signal is input to port P4 without passing through the second delay circuit 221, i.e., without being delayed by the second delay circuit 221. Port P4 is an example of a second port.

The controller 110 is further provided with ports Pr and Pt for communication signals. A received signal from an external device is input to port Pr, and a transmitted signal to an external device is output from port Pt.

[Controller operation (1): When the power supply voltage drops]
When the power supply voltage supplied to the wavelength-tunable laser device 1 drops, the wavelength-tunable light source stops operating. In this case, the controller 110 executes control to stop the operation of the semiconductor optical amplifier 70 before the wavelength-tunable light source stops operating.

Figure 3 is a flowchart showing the processing procedure performed by the controller 110 when the power supply voltage drops.

When the detection circuit 212 detects a drop in the power supply voltage that satisfies a predetermined condition, it outputs a detection signal (S11). The detection signal is input to the controller 110 via port P2.

Next, the controller 110 operates as a first stop control unit 110a and stops the operation of the semiconductor optical amplifier 70 in response to the input of the detection signal, for example, by turning off a switching element provided in the power supply line to the semiconductor optical amplifier 70 (S12).

On the other hand, the power supply voltage is input to the controller 110 via the first delay circuit 211. Here, the delay time by the first delay circuit 211 is set sufficiently longer than the time required from when the detection circuit 212 detects a drop in the power supply voltage until the operation of the semiconductor optical amplifier 70 is stopped by the operation of the first stop control unit 110a based on the detection. Therefore, if the drop in the power supply voltage is normal, the wavelength-tunable laser device 1 shuts down in response to the drop in the power supply voltage after S12 (Yes in S13). With this configuration and control, the operation of the semiconductor optical amplifier 70 stops in S12 and the output of laser light from the wavelength-tunable laser device 1 stops before the operation of the wavelength-tunable light source stops in the shutdown of the wavelength-tunable laser device 1 in S13, so that it is possible to avoid a situation in which the wavelength-tunable laser device 1 outputs laser light with an abnormal wavelength.

Figure 4 is a timing chart showing the output state and operation state of the signals of each part in this case. As shown in Figure 4, when the detection circuit 212 detects a drop in the power supply voltage below the threshold (t = t0), the detection signal output from the detection circuit 212 changes from L (low) level to H (high) level. As a result, the control signal of the first stop control unit 110a changes from L level to H level, and the semiconductor optical amplifier 70 (SOA) changes from the ON state to the OFF state, i.e., stops operating.

On the other hand, the output of the first delay circuit 211 falls below the threshold value at time t1, which is delayed by time T1 from time t0. As a result, the control signal of the first reset control unit 110e changes from H level to L level, and the light source device 10 (LD) changes from the ON state to the OFF state, i.e., stops operating. As a result, the wavelength tunable laser device 1 goes into a shutdown state. Note that the control entity that changes the light source device 10 from the ON state to the OFF state does not have to be the first reset control unit 110e.

In addition, if the power supply voltage experiences, for example, a momentary interruption, some kind of noise is mixed in, or a surge occurs, the detection circuit 212 detects a drop in the power supply voltage, and in response, the first stop control unit 110a stops the operation of the semiconductor optical amplifier 70, but the wavelength-tunable laser device 1 may not shut down. In this case, the wavelength-tunable laser device 1 enters an abnormal operating state in which the semiconductor optical amplifier 70 has stopped operating but other parts are still operating.

Therefore, in this embodiment, if the wavelength-tunable laser device 1 does not shut down after the operation of the semiconductor optical amplifier 70 stops in S12 (No in S13), the controller 110 operates as the first reset control unit 110e and resets the wavelength-tunable laser device 1 (S14). With this type of control, the wavelength-tunable laser device 1 can get out of an abnormal operating state in which, for example, the semiconductor optical amplifier 70 stops operating and other parts are operating.

At this time, the first reset control unit 110e may have a timer that measures the elapsed time from when the detection signal was input, and may execute the process of S14 when the elapsed time reaches a predetermined threshold value. This type of control makes it possible to more reliably or quickly escape from an abnormal operating state in which the semiconductor optical amplifier 70 has stopped operating and other parts are operating.

Figure 5 is a timing chart showing the output state and operation state of the signals of each part in this case. As shown in Figure 5, when the detection circuit 212 detects a drop in the power supply voltage below the threshold (t = t0), the detection signal output from the detection circuit 212 goes from L level to H level. As a result, the control signal of the first stop control unit 110a goes from L level to H level, and the semiconductor optical amplifier 70 goes from the ON state to the OFF state, i.e., it stops operating. Up to this point, it is the same as the case of Figure 4.

However, in the case of FIG. 5, the output of the first delay circuit 211 never falls below the threshold value. In such a case, the control signal of the first reset control unit 110e changes from H level to L level at time t2, which is a predetermined time T2 longer than time T1 from time t0, and the light source device 10 changes from the ON state to the OFF state. However, in this case, the light source device 10 enters an operation standby state (reset standby state) in which light output can be resumed by an enable command obtained by communication. Thereafter, in response to receiving the enable command, the wavelength tunable laser device 1 resumes operation (not shown).

[Controller operation (2): When a reset signal is input]
When the tunable laser device 1 is reset, the tunable light source stops operating before starting up. Therefore, in this case as well, the controller 110 executes control to stop the operation of the semiconductor optical amplifier 70 before the tunable light source stops operating upon resetting.

Figure 6 is a flowchart showing the processing procedure performed by the controller 110 when a reset signal is input.

When the controller 110 operating as the second stop control unit 110b detects a change in the reset signal input via port P4 that satisfies a predetermined condition, for example, a change from a high level higher than a predetermined threshold to a low level lower than the predetermined threshold (S21), it stops the operation of the semiconductor optical amplifier 70 (S22).

On the other hand, the reset signal is input to the controller 110 from port P3 via the second delay circuit 221. Here, the delay time by the second delay circuit 221 is set sufficiently longer than the time required for the second stop control unit 110b to receive the reset signal and stop the operation of the semiconductor optical amplifier 70. Therefore, when a normal reset signal is input, the controller 110 operates as the second reset control unit 110f and resets the wavelength-tunable laser device 1 after S22 based on the input to port P3 (Yes in S23). With this configuration and control, the operation of the semiconductor optical amplifier 70 stops in S22 and the output of laser light from the wavelength-tunable laser device 1 stops before the operation of the wavelength-tunable light source stops in the reset of the wavelength-tunable laser device 1 in S23, so that it is possible to avoid a situation in which the wavelength-tunable laser device 1 outputs laser light of an abnormal wavelength.

Figure 7 is a timing chart showing the output state and operation state of the signals of each part in this case. As shown in Figure 7, when the reset signal falls below the threshold (t = t0), the control signal of the second stop control part 110b goes from L level to H level, and the semiconductor optical amplifier 70 (SOA) goes from ON state to OFF state, i.e., stops operating.

On the other hand, the input to port P3 falls below the lower threshold at time t3, which is delayed by time T3 from time t0. As a result, the control signal of the second reset control unit 110f changes from H level to L level, and the light source device 10 changes from ON state to OFF state. In this case, however, the light source device 10 enters an operation standby state (reset standby state) in which light output can be resumed by an enable command obtained through communication. Thereafter, in response to receiving the enable command, the wavelength-tunable laser device 1 resumes operation (not shown). Note that when the input to port P3 exceeds the upper threshold, the control signal of the second reset control unit 110f returns from L level to H level.

In addition, a difference in the waveform of the reset signal between ports P3 and P4 may occur depending on whether or not the signal passes through the second delay circuit 221, and the second stop control unit 110b may detect the reset signal and stop the operation of the semiconductor optical amplifier 70, but the second reset control unit 110f may not detect the reset signal and may not reset the wavelength-tunable laser device 1. In this case, the wavelength-tunable laser device 1 may enter an abnormal operating state in which the semiconductor optical amplifier 70 has stopped operating but other parts are still operating.

Therefore, in this embodiment, if the wavelength-tunable laser device 1 is not reset after the operation of the semiconductor optical amplifier 70 stops in S22 (No in S23), the controller 110 operates as the third reset control unit 110g and resets the wavelength-tunable laser device 1 (S24). With this type of control, the wavelength-tunable laser device 1 can get out of an abnormal operating state in which, for example, the semiconductor optical amplifier 70 stops operating and other parts are operating.

At this time, the third reset control unit 110g may have a timer that measures the elapsed time from when the reset signal was input, and may execute the process of S24 when the elapsed time reaches a predetermined threshold value. This type of control makes it possible to more reliably or quickly escape from an abnormal operating state in which the semiconductor optical amplifier 70 has stopped operating and other parts are operating.

Figure 8 is a timing chart showing the output state and operation state of the signals of each part in this case. As shown in Figure 8, when the reset signal falls below the threshold (t = t0), the control signal of the second stop control part 110b goes from L level to H level, and the semiconductor optical amplifier 70 (SOA) goes from ON state to OFF state, i.e., it stops operating. Up to this point, it is the same as the case of Figure 7.

However, in the case of FIG. 8, the input to port P3 never falls below the threshold. In such a case, the control signal of the third reset control unit 110g changes from H level to L level at time t4, which is a predetermined time T4 longer than time T3 from time t0, and the light source device 10 changes from the ON state to the OFF state. However, in this case, the device enters an operation standby state (reset standby state) in which light output can be resumed by an enable command obtained by communication. Thereafter, in response to receiving the enable command, the wavelength-tunable laser device 1 resumes operation (not shown).

[Controller operation (3): When a reset command is input via communication]
In this case, the tunable light source is stopped when the tunable laser device 1 is reset, so the procedure is different from that of (2) above, but the controller 110 executes control to stop the operation of the semiconductor optical amplifier 70 before the tunable light source stops operating upon reset.

Figure 9 is a flowchart showing the processing steps performed by the controller 110 when a reset command is received.

When the controller 110, operating as the communication control unit 110d, receives a reset command from an external device via port Pr through communication with the external device (S31), it transmits a response to the reset command to the external device via port Pt (S32).

Next, the controller 110 operates as the third stop control unit 110c to stop the operation of the semiconductor optical amplifier 70 (S33), and then operates as the fourth reset control unit 110h to reset the wavelength-tunable laser device 1 (S34). With this type of control, the operation of the semiconductor optical amplifier 70 is stopped in S33 before the operation of the wavelength-tunable light source is stopped in the reset of the wavelength-tunable laser device 1 in S34, so that it is possible to avoid a situation in which the wavelength-tunable laser device 1 outputs laser light with an abnormal wavelength.

As described above, according to this embodiment, in the following cases: (1) when the power supply voltage drops, (2) when a reset signal is input, and (3) when a reset command is input via communication, the operation of the semiconductor optical amplifier 70 stops before the operation of the wavelength-tunable light source stops. This configuration has the advantage of being able to avoid a situation in which the wavelength-tunable laser device 1 outputs laser light with an abnormal wavelength.

[Second embodiment]
Fig. 10 is a block diagram showing a schematic configuration of a control device 100B (100) according to the second embodiment. As shown in Fig. 10, in this embodiment, the control device 100B has a filter circuit 213 that dulls the waveform of the power supply voltage input to the detection circuit 212. The filter circuit 213 is an example of a first filter circuit.

This configuration makes it possible to prevent the detection circuit 212 from overly sensitively reacting to fluctuations in the power supply voltage level, thereby preventing the semiconductor optical amplifier 70 from shutting down, which would otherwise be unnecessary.

In addition, in this embodiment, the control device 100B has a filter circuit 222 that dulls the waveform of the reset signal input to port P4 without passing through the second delay circuit 221. The filter circuit 222 is an example of a second filter circuit.

This configuration makes it possible to prevent the second stop control unit 110b from overly reacting to fluctuations in the level of the reset signal, thereby preventing the semiconductor optical amplifier 70 from shutting down, which would otherwise be unnecessary.

[Third embodiment]
11 is a schematic diagram of a wavelength-tunable laser device 1A of the third embodiment. As shown in FIG. 11, the light source device 10A has a wavelength-tunable light source section 10a and a semiconductor optical amplifier 70. The wavelength-tunable light source section 10a is not limited to the configuration of the first embodiment, and light sources of various configurations can be adopted. That is, regardless of the configuration of the wavelength-tunable light source section 10a, the present invention can be applied to a wavelength-tunable laser device 1A in which the operation and stop of the wavelength-tunable light source section 10a and the operation and stop of the semiconductor optical amplifier 70 can be independently controlled by the control device 100.

Although the above is an example of an embodiment of the present invention, the above embodiment is merely an example and is not intended to limit the scope of the invention. The above embodiment can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, etc. (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate.

1, 1A...Tunable wavelength laser device 10, 10A...Light source device 10a...Tunable wavelength light source section 11...Semiconductor laminated substrate 12...Mesa 20...SG-DBR section 30...Phase adjustment section 40...Gain section 50...Connection section 60...Ring resonator filter 70...Semiconductor optical amplifier 100, 100A, 100B...Control device 110...Controller 110a...First stop control section 110b...Second stop control section 110c...Third stop control section 110d...Communication control section 110e...First reset control section 110f...Second reset control section 110g...Third reset control section 110h...Fourth reset control section 120...Main memory section 130...Auxiliary memory device 211...First delay circuit 212...Detection circuit 213...Filter circuit (first filter circuit)
221...second delay circuit 222...filter circuit (second filter circuit)
C... coupling portion P1, P2... port P3... port (first port)
P4...Port (second port)
Pr, Pt...port

Claims (9)

A wavelength tunable laser device, comprising:
A wavelength-tunable light source that outputs a laser beam whose wavelength can be changed;
a semiconductor optical amplifier for optically amplifying a laser beam;
a controller controllable to at least shut down the semiconductor optical amplifier and to reset the tunable laser device;
a detection circuit that outputs a detection signal when a drop in a power supply voltage of the wavelength tunable laser device that satisfies a predetermined condition is detected;
a first delay circuit that delays a drop in a power supply voltage input to the controller;
Equipped with
The controller:
When the operation of the wavelength-tunable light source is stopped, the operation of the semiconductor optical amplifier is stopped before the operation of the wavelength-tunable light source is stopped ;
a first stop control unit that stops the operation of the semiconductor optical amplifier in response to an input of the detection signal ; 2. The wavelength-tunable laser device according to claim 1, wherein the controller has a first reset control unit that resets the wavelength-tunable laser device if the wavelength-tunable laser device does not shut down due to a drop in the power supply voltage after operation of the semiconductor optical amplifier is stopped under the control of the first stop control unit. The tunable laser device according to claim 2 , wherein the first reset control unit resets the tunable laser device when a predetermined time has elapsed after the input of the detection signal. 4. The tunable laser device according to claim 1 , further comprising a first filter circuit for smoothing a waveform of the power supply voltage input to the detection circuit. A wavelength tunable laser device, comprising:
a tunable light source that outputs a laser beam whose wavelength can be changed;
a semiconductor optical amplifier for optically amplifying a laser beam;
a controller controllable to at least shut down the semiconductor optical amplifier and to reset the tunable laser device;
a second delay circuit that delays a reset signal input to the controller;
Equipped with
The controller:
When the operation of the wavelength-tunable light source is stopped, the operation of the semiconductor optical amplifier is stopped before the operation of the wavelength-tunable light source is stopped;
a first port to which the reset signal is input via the second delay circuit;
a second port to which the reset signal is input without passing through the second delay circuit;
a second stop control unit that stops the operation of the semiconductor optical amplifier in response to the reset signal input via the second port;
a second reset control unit that resets the wavelength tunable laser device in response to the reset signal input via the first port;
A tunable laser device having the above structure. 6. The wavelength-tunable laser device according to claim 5, wherein the controller has a third reset control unit that resets the wavelength-tunable laser device if the wavelength-tunable laser device is not reset by the second reset control unit after operation of the semiconductor optical amplifier is stopped under the control of the second stop control unit. The tunable laser device according to claim 6 , wherein the third reset control unit resets the tunable laser device when a predetermined time has elapsed after the input of the reset signal. 8. The tunable laser device according to claim 5 , further comprising a second filter circuit for dulling a waveform of the reset signal input to the second port. The wavelength tunable laser device according to any one of claims 1 to 8 , wherein the computer operating as the controller is
A method for controlling a wavelength-tunable laser device, comprising: when an operation of the wavelength-tunable light source is to be stopped, stopping operation of the semiconductor optical amplifier before the operation of the wavelength-tunable light source is stopped.

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