JP2014192375A - Wavelength variable laser system and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength variable laser system, along with a control method thereof, capable of wavelength change in a short time, with progress of degradation being slow, with long life.SOLUTION: A wavelength variable laser system includes a cooperative control device 101 for sending temperature information and injection current information, a temperature control device 102 for controlling temperature of a semiconductor laser 104 according to the temperature information, and an injection current control device 103 for controlling injection current of the semiconductor laser according to the injection current information. The cooperative control device sends the injection current information and the temperature information such that, when wavelength is changed to a long wavelength side, an injection current value is instantaneously increased at a first time for starting wavelength change so as to be a wavelength on long wavelength side after the wavelength change, and temperature of the semiconductor laser is gradually increased from the first time through a second time, so that a predetermined temperature is reached at the second time, meanwhile, the injection current value is gradually decreased so that a predetermined current value is reached at the second time, for maintaining a wavelength on the long wavelength side from after wavelength change through the second time.

Description

  The present invention relates to a tunable laser system that changes the oscillation wavelength by controlling the temperature and injection current of a semiconductor laser, and a control method therefor.

  In optical communications, so-called wavelength division multiplexing, which transmits large amounts of information through a plurality of optical signals with different wavelengths to a single optical fiber, has been put into practical use, and this technology addresses the recent explosive increase in information. Yes. Furthermore, as a form of sophistication of wavelength division multiplexing transmission, by installing a wavelength filter for branching a specific wavelength at a node in the middle of the transmission path, the wavelength of the optical signal to be transmitted can be changed in advance and the destination node The network that selects is expected as a technology for further increasing the capacity.

  As a light source used in optical communication, a semiconductor laser is generally used. In order to change the wavelength of the optical signal, a method of changing the temperature of the semiconductor laser is generally used. For example, in the case of a distributed feedback semiconductor laser (DFB laser) having a wavelength of 1550 nm used in long-distance optical communication, when the temperature of the DFB laser is raised by 1 ° C., the wavelength increases by about 0.1 nm. Using this feature, a wavelength tunable laser has been put into practical use. In Non-Patent Document 1, in a semiconductor laser array in which a plurality of DFB lasers each having a different wavelength are arranged, the temperature of each DFB laser is changed, so that the plurality of DFB lasers can be arbitrarily selected within a wide wavelength range of 30 nm or more. A technique for generating a wavelength of λ is disclosed.

  In the current optical communication, a so-called wavelength path method is adopted in which the wavelength of an optical signal is fixed for a long period of time, thereby forming a wavelength path between specific nodes and performing communication for a long period of time. In the wavelength path method, when it becomes necessary to reconstruct a wavelength path in the event of a failure in an optical communication network or to add a wavelength path to cope with sudden increases in traffic, the wavelength of the optical signal can be changed. It corresponds to.

  Changing the temperature of the semiconductor laser takes at least several tens of seconds to change the temperature of the entire semiconductor chip of several hundred micrometers. Therefore, the wavelength path is changed over at least several tens of seconds. In the wavelength path method, since the wavelength path is fixed for a long period of time, even if it takes several tens of seconds to change the wavelength path, the influence of the communication amount in the long term on the throughput is almost negligible.

  On the other hand, as one of the future communication systems, an optical burst system that sequentially switches wavelengths in several tens of seconds is considered promising. In the optical burst method, information to be communicated is divided into fine optical bursts with a length of about several tens of seconds, and a different wavelength is assigned to each optical burst for each destination. This method has an advantage that electric processing with large power consumption is not required because a function for distributing the optical signal for each destination can be provided to the node. Accordingly, since it is necessary to switch the wavelength every several tens of seconds, a semiconductor laser whose wavelength changes within a time of several seconds or less is required in the optical burst method.

  One method for changing the laser wavelength of a semiconductor laser within a few seconds is to change the current injected into the semiconductor laser. A semiconductor laser emits light by injecting a current into a striped waveguide having a width of several micrometers to increase the number of electrons in the semiconductor. Increasing the injected current increases the light intensity. The local temperature of the part also rises and the wavelength increases. For example, in the case of a DFB laser having a wavelength of 1550 nm used in long-distance optical communication, if the injection current of the DFB laser is increased by 1 mA, the wavelength increases by about 0.1 nm. Since the heat capacity of the local region where the temperature change occurs is small, the local temperature change occurs in a short time of several seconds or less.

  In Non-Patent Document 2, by arranging a plurality of DFB lasers each having a different wavelength and changing the injection current of each DFB laser, the entire plurality of DFB lasers can be quickly and within a wide wavelength range of 30 nm or more. A technique for generating an arbitrary wavelength is disclosed.

H. Ishii et al., “Spectral linewidth reduction in widely used wavelength tunable DFB laser array”, IEEE Journal of Selected Topics in Quantum Electronics, 2009, Vol. 15, No. 3, p. 514-520. Ishii et al., “High-power operation of tunable DFB laser array by current control”, IEICE General Conference, 2005, C-4-12, p.319.

  However, it has been theoretically and experimentally revealed that increasing the injection current deteriorates the semiconductor laser and shortens the lifetime (time until it is determined to be a failure). Therefore, in the conventional method of changing the wavelength by changing the injection current to the semiconductor laser, there is a certain percentage of time for increasing the injection current amount, so that the deterioration progresses within that time, and as a result, the lifetime is shortened. There was a problem that the probability of failure during operation became high.

  The present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a wavelength tunable laser system capable of changing the wavelength in a short time within a few seconds and having a slow deterioration and a long life. .

  In order to achieve the above object, a wavelength tunable laser system according to the present invention transmits a semiconductor laser and temperature information for controlling the semiconductor laser to a desired set temperature, and an amount of current injected into the semiconductor laser. A cooperative control device for sending injection current information for controlling the current to a desired set value, a temperature control device for controlling the temperature of the semiconductor laser according to the temperature information, and an injection current into the semiconductor laser according to the injection current information The tunable laser system includes an injection current control device for controlling the semiconductor laser, wherein the cooperative control device changes the semiconductor laser after changing the wavelength when the laser wavelength of the semiconductor laser is changed from the short wavelength side to the long wavelength side. The injection current value is instantaneously increased at the first time when the wavelength change is started so that the laser wavelength of the laser becomes the wavelength on the long wavelength side. While gradually increasing the temperature of the semiconductor laser from the first time to the second time, the temperature of the semiconductor laser is set to a predetermined temperature at the second time, and from the first time to the second time The injection current value is gradually decreased until the time until the injection current value is set to a predetermined current value at the second time, and at least the first wavelength after the laser wavelength of the semiconductor laser is changed to the long wavelength side wavelength. The injection current information and the temperature information are transmitted so that the wavelength on the long wavelength side is maintained until the time of 2.

  The wavelength tunable laser system according to claim 2 is the wavelength tunable laser system according to claim 1, wherein the semiconductor laser includes at least a first semiconductor laser unit and a second semiconductor laser unit, and the cooperative control device Makes the injection current value to the first semiconductor laser unit instantaneously zero at the first time, and at the same time, instantaneously increases the injection current value of the second semiconductor laser unit, The injection current value of the second semiconductor laser unit is set to the predetermined current value at the second time while gradually decreasing the injection current value of the second semiconductor laser unit from time to the second time. As described above, the injection current information and the temperature information are transmitted.

  The wavelength tunable laser system according to claim 3 sends out a semiconductor laser and temperature information for controlling the semiconductor laser to a desired set temperature, and controls an injection current amount to the semiconductor laser to a desired set value. A cooperative control device for sending injection current information to control, a temperature control device for controlling the temperature of the semiconductor laser according to the temperature information, and an injection current control device for controlling the injection current into the semiconductor laser according to the injection current information When the laser wavelength of the semiconductor laser is changed from the long wavelength side to the short wavelength side, the cooperative control device starts the wavelength change from a first time. The semiconductor laser temperature is gradually decreased from the first time to the second time while maintaining the wavelength on the long wavelength side until the time of The temperature of the laser is set to a predetermined temperature at the second time, and the injection current value is gradually increased from the first time to the second time so that the injection current value is set at the second time. The injection current information and the injection current value are set to a predetermined current value, and the injection current value is instantaneously decreased at the second time so that the laser wavelength of the semiconductor laser becomes the short wavelength after the wavelength change. It is characterized by transmitting temperature information.

  The wavelength tunable laser system according to claim 4 is the wavelength tunable laser system according to claim 3, wherein the semiconductor laser includes at least a first semiconductor laser unit and a second semiconductor laser unit, and the cooperative control device Takes the injection current value of the first semiconductor laser unit from the first time to the second time while gradually increasing the injection current value of the first semiconductor laser unit from the first time to the second time. The injection current value of the current of the first semiconductor laser unit is instantaneously made zero at the second time, and at the same time, the injection current value of the second semiconductor laser unit is instantaneously increased. The injection current information and the temperature information are transmitted.

  According to a fifth aspect of the present invention, there is provided a control method for transmitting a semiconductor laser and temperature information for controlling the semiconductor laser to a desired set temperature, and controlling an injection current amount to the semiconductor laser to a desired set value. A coordinated control device for sending the injection current information, a temperature control device for controlling the temperature of the semiconductor laser according to the temperature information, and an injection current control device for controlling the injection current into the semiconductor laser according to the injection current information. In the control method of a tunable laser system provided, when the laser wavelength of the semiconductor laser is changed from a short wavelength side to a long wavelength side, the cooperative control device is configured such that the laser wavelength of the semiconductor laser is changed after the wavelength change. A first time for sending the injection current information for instantaneously increasing the injection current value at a first time when the wavelength change is started so that the wavelength becomes a longer wavelength side. And the coordinated control device, while gradually increasing the temperature of the semiconductor laser from the first time to the second time, to bring the temperature of the semiconductor laser to a predetermined temperature at the second time, The injection current value is set to a predetermined current value at the second time while gradually decreasing the injection current value from the first time to the second time, and the laser wavelength of the semiconductor laser is set to the long wavelength side. And a second step of sending out the injection current information and the temperature information for maintaining the wavelength on the long wavelength side at least until the second time after the change to the wavelength.

  The control method according to claim 6 is the control method according to claim 5, wherein the semiconductor laser is composed of at least a first semiconductor laser part and a second semiconductor laser part, and the first step includes The implanting control unit instantaneously increases the injection current value of the second semiconductor laser unit at the same time as the injection current value to the first semiconductor laser unit is instantaneously zeroed at the first time. A step of transmitting current information, wherein the cooperative control device gradually decreases the injected current value of the second semiconductor laser section from the first time to the second time. And sending the injection current information for setting the injection current value of the second semiconductor laser section to the predetermined current value at the second time.

  A control method according to claim 7 is for sending a semiconductor laser and temperature information for controlling the semiconductor laser to a desired set temperature, and controlling an injection current amount to the semiconductor laser to a desired set value. A coordinated control device for sending the injection current information, a temperature control device for controlling the temperature of the semiconductor laser according to the temperature information, and an injection current control device for controlling the injection current into the semiconductor laser according to the injection current information. A control method for a tunable laser system provided, wherein when the laser wavelength of the semiconductor laser is changed from a long wavelength side to a short wavelength side, the cooperative control device starts the wavelength change from a first time. The temperature of the semiconductor laser is gradually decreased from the first time to the second time while maintaining the wavelength on the long wavelength side until the time of 2. The injection temperature value is increased at the second time by gradually increasing the injection current value from the first time to the second time. The first step of sending the injection current information and the temperature information to be a predetermined current value, and the cooperative control device so that the laser wavelength of the semiconductor laser becomes the wavelength on the short wavelength side after the wavelength change And a second step of sending out the injected current information and the temperature information for instantaneously decreasing the injected current value at the second time.

  The control method according to claim 8 is the control method according to claim 7, wherein the semiconductor laser includes at least a first semiconductor laser part and a second semiconductor laser part, and the first step includes A coordinated control device gradually increases the injection current value of the first semiconductor laser unit from the first time to the second time, thereby changing the injection current value of the first semiconductor laser unit to the first time. The step of sending the injection current information to the predetermined current value at a time of 2, wherein the second step is performed by the cooperative control device to the first semiconductor laser unit at the second time. The method includes the step of sending the injection current information for instantaneously increasing the injection current value of the second semiconductor laser unit at the same time as making the injection current value zero instantaneously.

  According to the wavelength tunable laser system of the present invention, when changing the laser wavelength of the semiconductor laser, the wavelength change within a few seconds is performed by changing the injection current within a time within a few seconds, and before or after the wavelength change. By changing both the injection current and the temperature while keeping the wavelength constant within a few seconds, the ratio of the time when the amount of injected current is increased is reduced, resulting in a short time within a few seconds. It is possible to realize a wavelength tunable laser system that can change the wavelength and that has a slow progress and a long lifetime.

It is a figure which shows the structure of the wavelength tunable laser system which concerns on the 1st Embodiment of this invention. In the wavelength tunable laser system according to the first embodiment, when the laser wavelength of the semiconductor laser is changed to the longer wavelength side, the time change of the set value of the injection current information, the set temperature of the temperature information, and the laser wavelength of the semiconductor laser It is a figure which shows the relationship. In the wavelength tunable laser system according to the first embodiment, when the laser wavelength of the semiconductor laser is changed to the short wavelength side, the time change of the set value of the injection current information, the set temperature of the temperature information, and the laser wavelength of the semiconductor laser It is a figure which shows the relationship. It is a figure which shows the structure of the wavelength tunable laser system which concerns on the 2nd Embodiment of this invention. In the wavelength tunable laser system according to the second embodiment, when switching the semiconductor laser to which current is injected while increasing the temperature of the semiconductor laser array substrate, the set value of the injection current information, the set temperature of the temperature information, and the laser of the semiconductor laser It is a figure which shows the relationship of the time change with a wavelength. In the wavelength tunable laser system according to the second embodiment, the setting value of the injection current information, the setting temperature of the temperature information, and the laser of the semiconductor laser when switching the semiconductor laser to which current is injected while decreasing the temperature of the semiconductor laser array substrate It is a figure which shows the relationship of the time change with a wavelength.

  The wavelength tunable laser system according to each embodiment of the present invention will be described below.

<First Embodiment>
A wavelength tunable laser system 100 according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram showing a configuration of a wavelength tunable laser system 100 according to the first embodiment of the present invention. FIG. 1 shows a wavelength tunable laser system 100 including a cooperative control device 101, a temperature control device 102, an injection current control device 103, and a semiconductor laser 104.

  As shown in FIG. 1, the cooperative control device 101 sends temperature information for controlling the semiconductor laser 104 to a desired set temperature to the temperature control device 102, and sets the amount of current injected into the semiconductor laser 104 to a desired setting. The injection current information for controlling the value is sent to the injection current control device 103. The temperature control device 102 controls the temperature of the semiconductor laser 104 so that the semiconductor laser 104 reaches a desired set temperature according to the received temperature information, and the injection current control device 103 controls the injection current of the semiconductor laser 104 according to the received injection current information. The semiconductor laser 104 is controlled so that becomes a desired set value.

  FIG. 2 shows the relationship between changes in time of the set value of the injection current information, the set temperature of the temperature information, and the laser wavelength of the semiconductor laser when the wavelength is changed to the long wavelength side in the wavelength tunable laser system 100. FIG. 2A shows changes in injection current with respect to time, FIG. 2B shows changes in temperature with respect to time, and FIG. 2C shows changes in wavelength with time. The cooperative control device 101 performs cooperative control of the temperature information and the injection current information, and supplies the temperature control device 102 and the injection current device 103 so that the injection current value, temperature, and wavelength are as shown in FIG. Temperature information and injection current information are sent out. The same applies to FIG. 3 shown below.

The time for starting the wavelength change is t1. As shown in FIGS. 2A to 2C, before the time t1, the injection current value I is the lower current value _IL1 , the temperature T is the lower temperature _TL , and the wavelength of the semiconductor laser 104 is This is the wavelength on the short wavelength side. If instantaneously increased to the high-side current value I _H1 injection current value I at time t1 from the low-side current value I _L1 as shown in FIG. 2 (a), an increase in the injection current, as shown in FIG. 2 (c) Accordingly, the wavelength changes to the long wavelength side in a short time Δt within several seconds. Here, the high-side current value I _H1 is set so that the laser wavelength of the semiconductor laser becomes a desired value after the wavelength change based on the low-side current value _IL1 of the semiconductor laser at the time t1 when the wavelength change is started. Can be set.

Thereafter, as shown in FIGS. 2A to 2C, the relationship between the temperature T and the injected current value I is maintained so that the wavelength is maintained at a constant value on the long wavelength side from time t1 to time t2. while, and the injection current I is decreased gradually injection current value I such that the high-side current value I _H1 following the predetermined low-side current value I _L2 after time t2, the high-side temperature T at time t2 _The temperature T is gradually increased so as to be _H1 . Here, the high side temperature T _H1 may be the wavelength of the semiconductor laser 104 based on the low-side current value I _L2 at time t2 is set to be a desired value. The relationship between the temperature T at which the above-mentioned wavelength maintains a constant value on the long wavelength side and the injection current value I is the temperature T at which the wavelength maintains a constant value on the long wavelength side in advance by preliminary experiments. And the injection current value I, and the relationship can be obtained by approximating the relationship with a polynomial.

As a result, after time t2, the semiconductor laser 104 while keeping the state in which the wavelength has changed to a desired long wavelength side, the injection current value I is a high-side current value I _H1 following the desired low-side current value I _L2 be able to. That is, the injection current value I becomes equal to or lower than the high-order current value I _{H1 in} the time of several seconds or more after the time t1, while causing the wavelength change to the long wavelength side instantaneously in a short time Δt within several seconds at the time t1. Therefore, in the present invention, it is not necessary to maintain the injection current always high after the wavelength change in order to maintain the wavelength on the long wavelength side as in the case of controlling the wavelength only by the conventional injection current change, The proportion of time during which the amount of injected current is increased can be reduced, whereby the progress of deterioration of the semiconductor laser 104 is delayed and the life is increased, and as a result, the failure probability can be lowered.

  FIG. 3 shows the relationship between changes in time of the set value of the injection current information, the set temperature of the temperature information, and the laser wavelength of the semiconductor laser when the wavelength is changed to the short wavelength side in the wavelength tunable laser system 100. 3A shows the change in the injection current with respect to time, FIG. 3B shows the change in temperature with respect to time, and FIG. 3C shows the change in wavelength with time.

The time for starting the wavelength change is t4. As shown in FIGS. 3A to 3C, before the time t3, the injection current value I is the low-side current value _IL3 , the temperature T is the high-side temperature _TH2 , and the wavelength of the semiconductor laser 104 is This is the wavelength on the long wavelength side. Between time t3 and time t4, while maintaining the relationship between the temperature T and the injected current value I so that the wavelength of the semiconductor laser 104 maintains a constant value on the long wavelength side before time t4, the injected current value I is increases gradually injection current value I such that the high-side current value I _H2 at time t4 before a wavelength change, also gradually decreases the temperature T so that the lower side temperature T _L2 at time t4. Here, the high-side current value I _H2, the wavelength of the semiconductor laser 104 is set to a value of the long-wavelength side of the front wavelength change based on the low side temperature T _L2 of the semiconductor laser 104 at time t4 Can do. Further, the lower temperature T _L2 can be set so that the wavelength of the semiconductor laser 104 becomes a desired short wavelength side value after the wavelength change based on the lower current value I _L4 after time t4.

Thereafter, as shown in FIG. 3 (a), when the injection current value I is instantaneously decreased from the high-order current value _IH2 to the desired low-order current value _IL4 at time t4, as shown in FIG. 3 (c). Thus, as the injection current decreases, the wavelength changes to the short wavelength side in a short time Δt within several seconds.

As a result, from time t3 to time t4, the semiconductor laser 104 maintains the wavelength state on the long wavelength side before the wavelength change to the short wavelength side, and the injection current value I is a value equal to or lower than the high-order side current value _IH2. It becomes. That is, the injection current value I becomes equal to or lower than the high-order current value I _H2 before the time t4 while causing the wavelength change to the short wavelength side instantaneously in a short time Δt within several seconds at the time t4. Therefore, in the present invention, since it is not necessary to always maintain the injection current in a high state before the wavelength change in order to maintain the wavelength on the long wavelength side as in the case of controlling the wavelength only by the conventional injection current change, The proportion of time during which the amount of injected current increases can be reduced, the progress of deterioration of the semiconductor laser 104 is slowed and the life is extended, and as a result, the failure probability can be lowered.

<Second Embodiment>
A wavelength tunable laser system according to the second embodiment of the present invention will be described with reference to FIGS.

  FIG. 4 is a diagram showing a configuration of a wavelength tunable laser system 200 according to the second embodiment of the present invention. FIG. 4 shows a wavelength tunable laser system 200 including a cooperative control device 201, a temperature control device 202, an injection current control device 203, and a semiconductor laser array substrate 204. The semiconductor laser array substrate 204 includes a first semiconductor laser 205 and a second semiconductor laser 206.

  As shown in FIG. 4, the cooperative control apparatus 201 sends temperature information for controlling the semiconductor laser array substrate 204 to a desired set temperature to the temperature control apparatus 202, and the first semiconductor laser 205 and the second semiconductor laser 205 Injection current information for controlling the injection current amount to the semiconductor laser 206 to a desired set value is sent to the injection current control device 203. The temperature control device 202 controls the temperature of the semiconductor laser 204 so that the semiconductor laser array substrate 204 has a desired set temperature according to the received temperature information. The injection current control device 203 controls the first semiconductor according to the received injection current information. The first semiconductor laser 205 and the second semiconductor laser 206 are respectively controlled so that the injection currents of the laser 205 and the second semiconductor laser 206 become desired set values, respectively.

  Here, the first semiconductor laser 205 and the second semiconductor laser 206 are arranged in an array on the semiconductor laser array substrate 204 close to each other. Accordingly, the temperature of the semiconductor laser array substrate 204 is controlled by the temperature control device 202, and the temperature of the first semiconductor laser 205 and the second semiconductor laser 206 is also the same except that the temperature changes due to the injection current. Be controlled.

  FIG. 5 shows a set value of injection current information and a set temperature of temperature information when switching a semiconductor laser for current injection while increasing the temperature of the semiconductor laser array substrate in the wavelength tunable laser system 200 according to the second embodiment. The relationship of the change with time of the laser wavelength of the semiconductor laser is shown. FIGS. 5A to 5C show the injection current change, the temperature change, and the wavelength change with time in the first semiconductor laser 205, respectively. FIGS. 5D to 5F show the second change. The change in injection current, change in temperature, and change in wavelength with respect to time in the semiconductor laser 206 of FIG. The coordinated control device 201 controls the temperature information and the injection current information in a coordinated manner, and supplies the temperature control device 202 and the injection current device 203 so that the injection current value, temperature, and wavelength are as shown in FIG. Temperature information and injection current information are sent out. The same applies to FIG. 6 shown below.

As shown in FIGS. 5A and 5D, at the time t1 when the wavelength change is started, the injection current of the first semiconductor laser 205 is made zero, and at the same time, the current is injected into the second semiconductor laser 206. The current injection is switched from the first semiconductor laser 205 to the second semiconductor laser 206. At the switching time t1, as shown in FIG. 5 (e), the temperature of the second semiconductor laser 206 is lower than the predetermined high side temperature T _H1 to obtain a desired wavelength. Therefore, the injection current value to the second semiconductor laser 206 is set to the high-side current value I _H1 so that a desired wavelength can be obtained even when the temperature is lower than the predetermined temperature.

Thereafter, as shown in FIGS. 5D to 5F, the temperature T of the second semiconductor laser 206 is set so that the wavelength of the second semiconductor laser 206 is constant from time t1 to time t2. reducing the injection current value while keeping the relationship between the I, and the injection current value I gradually injection current value I such that the high-side current value I _H1 following the predetermined low-side current value I _L2 at the time t2 after In addition, the temperature T is gradually increased so as to _{reach the} higher temperature T _H1 at time t2.

As a result, after time t2, the second semiconductor laser 206 maintains the state in which the wavelength has changed to the desired long wavelength side, while the injection current value I is the desired low-side current value I that is equal to or less than the high-side current value _{IH1. L2} can be set. That is, several seconds after time t1 while switching the injection current from the first semiconductor laser 205 to the second semiconductor laser 206 at time t1 and causing a wavelength change to the long wavelength side instantaneously within a short time Δt within several seconds. The injection current value I becomes equal to or lower than the high-order current value I _{H1 in the} above time. Therefore, in the present invention, the proportion of time during which the amount of injected current increases can be reduced, thereby slowing down the progress of the degradation of the second semiconductor laser 206 and extending the life, thereby reducing the failure probability. Is possible.

  FIG. 6 shows the setting value of the injection current information and the setting temperature of the temperature information when switching the semiconductor laser for current injection while decreasing the temperature of the semiconductor laser array substrate in the wavelength tunable laser system 200 according to the second embodiment. The relationship of the change with time of the laser wavelength of the semiconductor laser is shown. FIGS. 6A to 6C show an injection current change, a temperature change, and a wavelength change with respect to time in the first semiconductor laser 205, respectively. FIGS. 6D to 6F show the second change. The change in injection current, change in temperature, and change in wavelength with respect to time in the semiconductor laser 206 of FIG.

As shown in FIGS. 6A and 6D, at the time t4 when the wavelength change is started, the injection current of the first semiconductor laser 205 is set to zero, and the current is injected into the second semiconductor laser 206 at the same time. The current injection is switched from the first semiconductor laser 205 to the second semiconductor laser 206. At the switching time t4, as shown in FIG. 6E, in order to obtain a desired wavelength on the short wavelength side from the second semiconductor laser 206, the temperature of the second semiconductor laser 206 is a high level before the time t3. It must be set lower than the side temperature _TH2 .

Therefore, while maintaining the relationship between the temperature T and the injection current value I so that the wavelength of the first semiconductor laser 205 maintains a constant value on the long wavelength side before the time t4 from the time t3 to the time t4, and The injection current value I is gradually increased so that the injection current value I to the first semiconductor laser 205 becomes the high-order current value I _H2 at time t4 before the wavelength change, and at time t4, the first semiconductor laser 205 is also increased. and the temperature T of the second semiconductor laser 206 gradually decreases the temperature T so that the lower side temperature T _L2.

As a result, during the period from time t3 to time t4, the first semiconductor laser 205 maintains the wavelength state on the long wavelength side before the wavelength change to the short wavelength side, while the injection current value I is the higher current value I _H2. It becomes the following values. That is, while the injection current is switched from the first semiconductor laser 205 to the second semiconductor laser 206 at time t4, the wavelength change to the short wavelength side instantaneously occurs within a few seconds, and before time t4, the injection current value I is The high-order current value _IH2 or less. As a result, the proportion of time during which the amount of injected current increases can be reduced, the progress of deterioration of the second semiconductor laser 206 is delayed, the life is increased, and as a result, the failure probability can be lowered.

  As described above, in the wavelength tunable laser system, when the laser wavelength of the semiconductor laser is changed, the wavelength change within a few seconds is performed by changing the injection current within a time within a few seconds, and before or after the wavelength change. By changing both the injection current and temperature while keeping the wavelength constant within a few seconds or longer, the ratio of the time when the amount of injected current increases is reduced, resulting in a shorter wavelength within a few seconds. It is possible to construct a wavelength tunable laser system that can change and that has a slow deterioration and a long lifetime.

  In the wavelength tunable laser system 200 according to the second embodiment, the two first semiconductor lasers 205 and the second semiconductor laser 206 are provided. However, the present invention is not limited thereto, and the semiconductor laser array is not limited thereto. A plurality of semiconductor lasers may be provided on the substrate.

  As mentioned above, although each embodiment of the wavelength tunable laser system according to the present invention has been described in detail, the specific configuration is not limited to each embodiment, and includes design changes and the like without departing from the gist of the present invention. It is.

101, 201 Cooperative control device 102, 202 Temperature control device 103, 203 Injection current control device 104 Semiconductor laser 204 Semiconductor laser array substrate 205 First semiconductor laser 206 Second semiconductor laser

Claims (8)

A semiconductor laser;
A cooperative controller that sends temperature information for controlling the semiconductor laser to a desired set temperature, and sends injection current information for controlling the amount of current injected into the semiconductor laser to a desired set value;
A temperature control device for controlling the temperature of the semiconductor laser according to the temperature information;
An tunable laser system comprising: an injection current control device that controls an injection current to the semiconductor laser according to the injection current information,
When the laser wavelength of the semiconductor laser is changed from the short wavelength side to the long wavelength side, the cooperative control device changes the wavelength so that the laser wavelength of the semiconductor laser becomes the wavelength on the long wavelength side after the wavelength change. The injection current value is instantaneously increased at the first time to start, and the temperature of the semiconductor laser is gradually increased from the first time to the second time while the temperature of the semiconductor laser is gradually increased. The semiconductor laser is set to a predetermined current value at the second time while gradually decreasing the injected current value from the first time to the second time. The injection current information and the temperature information are transmitted so that the wavelength on the long wavelength side is maintained at least until the second time after the laser wavelength changes to the wavelength on the long wavelength side. Tunable laser system according to claim. 2. The tunable laser system according to claim 1, wherein the semiconductor laser includes at least a first semiconductor laser part and a second semiconductor laser part,
The cooperative control device instantaneously increases the injection current value of the second semiconductor laser unit at the same time that the injection current value to the first semiconductor laser unit is instantaneously zero at the first time, While gradually decreasing the injection current value of the second semiconductor laser unit from the first time to the second time, the injection current value of the second semiconductor laser unit is set to the second time at the second time. The tunable laser system, wherein the injection current information and the temperature information are transmitted so as to have a predetermined current value. A semiconductor laser;
A cooperative controller that sends temperature information for controlling the semiconductor laser to a desired set temperature, and sends injection current information for controlling the amount of current injected into the semiconductor laser to a desired set value;
A temperature control device for controlling the temperature of the semiconductor laser according to the temperature information;
An tunable laser system comprising: an injection current control device that controls an injection current to the semiconductor laser according to the injection current information,
In the case where the laser wavelength of the semiconductor laser is changed from the long wavelength side to the short wavelength side, the cooperative control device maintains the wavelength on the long wavelength side from the first time to the second time when the wavelength change is started. However, the temperature of the semiconductor laser is gradually decreased from the first time to the second time to bring the temperature of the semiconductor laser to a predetermined temperature at the second time, and from the first time. The injection current value is gradually increased until the second time to make the injection current value a predetermined current value at the second time, and the injection current value is instantaneously decreased at the second time to The wavelength tunable laser system, wherein the injection current information and the temperature information are transmitted so that a laser wavelength of the semiconductor laser becomes a wavelength on the short wavelength side after wavelength change. The wavelength tunable laser system according to claim 3, wherein the semiconductor laser is composed of at least a first semiconductor laser part and a second semiconductor laser part,
The coordinated control device increases the injection current value of the first semiconductor laser unit while gradually increasing the injection current value of the first semiconductor laser unit from the first time to the second time. A predetermined current value is set at a second time, and the injection current value of the current of the first semiconductor laser unit is instantaneously made zero at the second time, and at the same time, the injection current value of the second semiconductor laser unit The wavelength tunable laser system is characterized in that the injection current information and the temperature information are transmitted so as to increase instantaneously. A semiconductor laser;
A cooperative controller that sends temperature information for controlling the semiconductor laser to a desired set temperature, and sends injection current information for controlling the amount of current injected into the semiconductor laser to a desired set value;
A temperature control device for controlling the temperature of the semiconductor laser according to the temperature information;
An tunable laser system control method comprising: an injection current control device that controls an injection current to the semiconductor laser according to the injection current information, wherein the laser wavelength of the semiconductor laser is changed from a short wavelength side to a long wavelength side If you want to
The injection current that instantaneously increases the injection current value at a first time when the cooperative control device starts the wavelength change so that the laser wavelength of the semiconductor laser becomes the wavelength on the long wavelength side after the wavelength change. A first step of sending information;
The coordinated control device gradually increases the temperature of the semiconductor laser from the first time to the second time while setting the temperature of the semiconductor laser to a predetermined temperature at the second time, and the first time The injection current value is set to a predetermined current value at the second time while gradually decreasing the injection current value from the time to the second time, and the laser wavelength of the semiconductor laser is set to the wavelength on the long wavelength side. A control method comprising: a second step of sending the injection current information and the temperature information to maintain the wavelength on the long wavelength side from at least the second time until after the change. 6. The control method according to claim 5, wherein the semiconductor laser is composed of at least a first semiconductor laser part and a second semiconductor laser part,
In the first step, the cooperative control device instantaneously sets the injection current value to the first semiconductor laser unit to zero at the first time, and at the same time, the injection current of the second semiconductor laser unit. Sending the injected current information to increase the value instantaneously;
In the second step, the cooperative control device causes the second semiconductor laser unit to gradually decrease the injection current value of the second semiconductor laser unit from the first time to the second time. A step of sending the injected current information to make the injected current value of the predetermined current value at the second time. A semiconductor laser;
A cooperative controller that sends temperature information for controlling the semiconductor laser to a desired set temperature, and sends injection current information for controlling the amount of current injected into the semiconductor laser to a desired set value;
A temperature control device for controlling the temperature of the semiconductor laser according to the temperature information;
A control method of a wavelength tunable laser system comprising: an injection current control device that controls an injection current to the semiconductor laser according to the injection current information, wherein the laser wavelength of the semiconductor laser is changed from a long wavelength side to a short wavelength side If you want to
The temperature of the semiconductor laser from the first time to the second time while the cooperative control device maintains the wavelength on the long wavelength side from the first time to the second time at which the wavelength change starts. Is gradually decreased to bring the temperature of the semiconductor laser to a predetermined temperature at the second time, and the injection current value is gradually increased from the first time to the second time to increase the injection current. A first step of sending the injected current information and the temperature information to make a value a predetermined current value at the second time;
The injection current information and the temperature information that the cooperative control device instantaneously decreases the injection current value at the second time so that the laser wavelength of the semiconductor laser becomes the wavelength on the short wavelength side after the wavelength change. And a second step of sending the message. The control method according to claim 7, wherein the semiconductor laser includes at least a first semiconductor laser part and a second semiconductor laser part,
In the first step, the cooperative control device gradually increases the injection current value of the first semiconductor laser unit from the first time to the second time to increase the first semiconductor laser unit. Sending the injection current information to make the injection current value of the predetermined current value at the second time,
In the second step, the cooperative control device instantaneously sets the injection current value to the first semiconductor laser unit to zero at the second time, and at the same time, the injection current of the second semiconductor laser unit. A control method comprising the step of sending the injection current information for instantly increasing the value.

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