JP2014033127A - Abnormal current detection method of integrated optical element and integrated optical element assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect abnormality of a drive current for driving a semiconductor laser without installing a current monitor circuit for detecting the current value, in a laser with a control circuit, and to make the laser with a control circuit compact.SOLUTION: A power monitor PD 34 for detecting the output of laser light L emitted from a DFB laser 31 and amplified by an SOA 32 detects stray light Lof the DFB laser 31 being driven with the drive current. Based on the power of the stray light Ldetected by the power monitor PD 34, abnormality of a drive current supplied to the DFB laser 31 from a DFB drive circuit 40 is detected by a CPU 20 for controlling the DFB laser 31. Furthermore, abnormality of a drive current supplied to the SOA 32 from an SOA drive circuit 50 is detected by a CPU 20 for controlling the SOA 32.

Description

  The present invention relates to an optical integrated element abnormal current detection method and an optical integrated element assembly for detecting an abnormal drive current when performing ultrahigh-speed optical transmission, particularly in a wavelength tunable laser module.

  A control circuit for a general semiconductor laser module such as a wavelength tunable laser module is provided with a current monitor circuit for monitoring the drive current of the semiconductor laser. The monitor information detected by the current monitor circuit is supplied to the control circuit and processed by an internal central processing unit (CPU). The CPU calculates the difference between the value (monitor value) detected by monitoring and the target value, and controls the output of the drive current flowing through the semiconductor laser so that the value of this difference becomes zero.

  When an abnormal current flows through the semiconductor laser, the current monitor circuit monitors this abnormal current value. The monitor information of the abnormal current value is supplied to the control circuit, and the current abnormality is detected by the control circuit.

  Conventionally, there has been proposed an optical module abnormality detection method having an auto power control function that makes the light output of the transmission light source constant by the monitor current of the light receiving element that receives the monitor light of the light output of the transmission light source (Patent Document). 1). This technique includes a step of detecting a current value flowing through a predetermined portion of an optical module, a step of storing a past value of the detected current value, and a difference value between the stored past value and a currently detected value. And a step of generating an alarm signal indicating the necessity of preventive maintenance when the obtained difference value exceeds a predetermined threshold value.

  Even in an optical integrated device equipped with a distributed feedback (DFB) semiconductor laser device or a semiconductor optical amplifier (SOA), a current monitor circuit mounted on the control circuit supplies the drive current of the optical integrated device. Abnormal current is detected by direct monitoring. Similarly, in the technique described in Patent Document 1, an abnormal current is detected by directly detecting a current value flowing through a predetermined portion of the optical module.

JP 2002-76506 A

  Incidentally, there is a demand for downsizing a laser with a control circuit in which a semiconductor laser module is mounted. On the other hand, it is necessary to install a current monitor circuit as an application for detecting a current abnormality or a shift in lock wavelength or power. Further, in the case of a laser with a control circuit equipped with DFB, SOA, etc., a current monitor circuit for monitoring the drive current is required for each of DFB and SOA. This makes it difficult to reduce the size of the control circuit, making it difficult to reduce the size of the laser with the control circuit.

  The present invention has been made in view of the above, and an object of the present invention is to provide an integrated optical device without installing a current monitor circuit for monitoring a current value in a laser with a control circuit including a semiconductor laser module. It is possible to provide an optical integrated device abnormal current detection method and an optical integrated device assembly that can detect an abnormality in a drive current flowing through the optical integrated device and can be downsized.

  In order to solve the above-described problems and achieve the above object, an abnormal current detection method for an optical integrated device according to the present invention is a laser light output detection method for detecting the output of laser light emitted from an optical integrated device having a semiconductor laser. Based on the leakage light detection step of detecting leakage light that is not guided in the optical integrated element of the laser light by the means and the intensity of leakage light detected by the laser light output detection means, the control means drives the semiconductor laser. And an abnormality detection step of detecting an abnormality in current.

  The method for detecting an abnormal current of an optical integrated device according to the present invention is the above-described invention, wherein the semiconductor laser is a distributed feedback semiconductor laser, and the laser light output detecting means is an optical amplifying means for amplifying the laser light emitted from the semiconductor laser. The amplified laser beam can be detected.

  An optical integrated device assembly according to the present invention includes an optical integrated device having a semiconductor laser, laser light guided in the optical integrated device out of laser light emitted from the optical integrated device, and leakage light not guided in the optical integrated device. Based on the intensity of leakage light detected by the laser light output detection means, a control means configured to be able to detect an abnormality in the drive current of the semiconductor laser, It is characterized by providing.

  An optical integrated device assembly according to the present invention is the optical integrated device assembly according to the above invention, wherein the optical integrated device is configured to emit a plurality of semiconductor lasers configured to emit laser beams having different wavelengths, and a laser beam emitted from each of the plurality of semiconductor lasers. A plurality of optical waveguides each configured to be able to guide light, an optical combiner configured to be able to combine laser light guided by the plurality of optical waveguides, and a semiconductor optical amplifier that amplifies the laser light output from the optical combiner It is characterized by being integrated.

  According to the method for detecting an abnormal current of an optical integrated device and the optical integrated device assembly according to the present invention, in a laser with a control circuit, the drive current flowing through the semiconductor laser can be detected without installing a current monitor circuit for detecting the current value. Abnormalities can be detected and downsizing can be realized.

FIG. 1 is a schematic view showing a tunable laser assembly according to a first embodiment of the present invention. FIG. 2 is a schematic diagram showing details of the optical integrated device in the laser module mounted on the wavelength tunable laser assembly according to the first embodiment of the present invention. FIG. 3 is a schematic diagram showing a tunable laser assembly according to the prior art. FIG. 4 is a schematic diagram showing a tunable laser assembly according to the prior art. FIG. 5 is a schematic view showing a wavelength tunable laser assembly according to the second embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. Further, the present invention is not limited to the embodiments described below.

  First, an optical integrated device abnormal current detection method and an optical integrated device assembly according to a first embodiment of the present invention will be described. FIG. 1 shows an example of a laser with a control circuit, which is an optical integrated device assembly including the semiconductor optical integrated device according to the first embodiment.

(Tunable laser assembly)
As shown in FIG. 1, an tunable laser assembly (ITLA) 100 as a laser with a control circuit according to the first embodiment includes a CPU 20, a laser module 30, and a DFB drive circuit on a printed circuit board 10. 40, the SOA drive circuit 50, and the current monitor circuit 60 are provided at predetermined positions.

  The CPU 20 is provided with digital / analog converters (DACs) 21 and 22 for outputting analog signals to the outside, and an analog / digital converter (ADC) 23 for inputting analog signals from the outside. ing. The DACs 21 and 22 and the ADC 23 are built in the CPU 20, but can be provided outside the CPU 20. The CPU 20 as a control unit supplies a control signal to the DFB drive circuit 40 through the DAC 21 to control the DFB drive circuit 40 and the DFB laser unit 31, and supplies a control signal to the SOA drive circuit 50 through the DAC 22. 50 and SOA 32 are controlled.

  The laser module 30 is provided with at least an optical integrated element having a DFB laser unit 31 and an optical amplifier (SOA) 32, a beam splitter 33 and a power monitor photodiode (power monitor PD) 34 constituting an optical system. Yes.

  The DFB drive circuit 40 drives the DFB laser unit 31 by supplying a drive current to the DFB laser unit 31. The SOA drive circuit 50 drives the SOA 32 by supplying a drive current to the SOA 32.

  The beam splitter 33 allows most of the laser light L emitted from the DFB laser unit 31 and amplified by the SOA 32 to pass therethrough, and partly branches. The power monitor PD 34 as the laser light output detection means detects the laser light L branched by the beam splitter 33 and outputs a current corresponding to the detected light intensity. The current output from the power monitor PD 34 is input to the current monitor circuit 60. The current monitor circuit 60 outputs a monitor value corresponding to the magnitude of the current input as monitor information. The monitor value output from the current monitor circuit 60 is supplied to the CPU 20 via the ADC 23.

  The CPU 20 supplies a control signal to the SOA drive circuit 50 via the DAC 22 based on the monitor value supplied from the current monitor circuit 60. The SOA drive circuit 50 controls the drive of the SOA 32 based on a control signal from the CPU 20. Specifically, the CPU 20 controls the SOA drive circuit 50 so that when the current value output from the power monitor PD 34 is larger than a predetermined upper limit value, the drive current supplied to the SOA 32 is decreased or the power monitor PD 34 When the output current value is smaller than the predetermined lower limit value, the drive current supplied to the SOA 32 is increased.

(Configuration of optical integrated device)
FIG. 2 is a detailed schematic diagram of an optical integrated device (integrated semiconductor laser device) having the DFB laser unit 31 and the SOA 32. As shown in FIG. 2, the optical integrated device provided in the laser module 30 includes a plurality of DFB laser stripes 31-1 to 31-n (n: an integer equal to or larger than 2) provided via a trench groove 31 c therebetween. A plurality of optical waveguides 31a-1 to 31a-n, a multimode interferometer (MMI) optical combiner 31b, and an SOA 32 are integrated and embedded on one semiconductor substrate. .

  Each of the DFB laser stripes 31-1 to 31-n as a semiconductor laser is an edge-emitting laser having a stripe-shaped buried structure, and is formed at a predetermined pitch in the width direction at one end of the optical integrated device. The DFB laser stripes 31-1 to 31-n have different wavelengths of the diffraction gratings provided in the DFB laser stripes 31-1 to 31-n so that the wavelength of the output light is in a predetermined range, for example, 1530 nm to 1570 nm. It is comprised so that it may differ in the range. The laser oscillation wavelengths of the DFB laser stripes 31-1 to 31-n can be adjusted by changing the set temperature of the optical integrated device. That is, the optical integrated device realizes a wide wavelength tunable range by switching the driving DFB laser stripes 31-1 to 31-n and controlling the temperature.

  The MMI optical combiner 31b is formed substantially at the center of the optical integrated device. The optical waveguides 31a-1 to 31a-n are formed between the DFB laser stripes 31-1 to 31-n and the MMI optical combiner 31b, and the DFB laser stripes 31-1 to 31-n and the MMI are formed. The confluence 31b is optically connected. The SOA 32 is formed at one end of the optical integrated device opposite to the DFB laser stripes 31-1 to 31-n.

  The operation of this optical integrated device will be described. First, one DFB laser stripe selected from the DFB laser stripes 31-1 to 31-n is driven. Since the trench 31c electrically separates the DFB laser stripes 31-1 to 31-n, the separation resistance between the DFB laser stripes is increased. This makes it easy to select and drive one of the DFB laser stripes 31-1 to 31-n.

  Next, the optical waveguide optically connected to the driven DFB laser stripe among the plurality of optical waveguides 31a-1 to 31a-n guides the laser light output from the driving DFB laser stripe. . The MMI optical combiner 31b passes the light guided through the optical waveguide and outputs the light from the output port 31d. The SOA 32 amplifies the light output from the output port 31d and outputs it from the output end 32a. The SOA 32 is used to compensate for the loss of light from the driven DFB laser stripe by the MMI optical combiner 31b and to obtain a laser light output having a desired intensity from the output end 32a.

When the optical integrated device to work, light emitted from the output port 31d side of the end surface 31e of the MMI light converging device 31b becomes stray light L _0. That is, the DFB laser unit 31 emits a laser beam L that is guided and stray light L ₀ that is a laser beam that is not guided as leakage light. The laser beam L is guided from the MMI combiner 31b to the SOA 32 via the output port 31d. On the other hand, the stray light L ₀ is emitted without being guided to the SOA 32. Incidentally, there are cases where such light emitted from the bent portion of the optical waveguide 31a-1 through 31a-n are also emitted as stray light L _0.

(Abnormality detection of drive current)
Therefore, in the first embodiment, detection of abnormality of the drive current output from the DFB drive circuit 40 is performed as follows.

That is, as shown in FIG. 1, the stray light L ₀ is configured to be detectable by the power monitor PD 34. Here, according to the knowledge of the present inventor, the power of the stray light L ₀ emitted from the DFB laser unit 31 changes according to the drive current supplied to the DFB laser unit 31 by the DFB drive circuit 40. Therefore, in the state where the SOA 32 is not driven, the stray light L ₀ emitted from the DFB laser unit 31 is detected by the power monitor PD 34 and the power is detected to detect the abnormality of the drive current output by the DFB drive circuit 40. It becomes possible to detect.

Specifically, first, the CPU 20 outputs in advance the monitor value output by the power monitor PD 34 and monitored by the current monitor circuit 60 when the drive current supplied by the DFB drive circuit 40 to the DFB laser unit 31 is normal. , And keep it as a target value. Then, the CPU 20 calculates the difference between the monitor value monitored by the current monitor circuit 60 according to the detection of the power of the stray light L ₀ by the power monitor PD 34 and the held target value. When this difference becomes greater than or equal to a predetermined upper limit value or less than a predetermined lower limit value, the CPU 20 determines that the current value of the drive current output from the DFB drive circuit 40 is abnormal. Thereby, the CPU 20 can detect an abnormality in the drive current output from the DFB drive circuit 40.

Then, the CPU 20 controls the DFB drive circuit 40 through the DAC 21 so that the current value output from the DFB drive circuit 40 becomes a normal current value. The power monitor PD 34 detects the power of the stray light L ₀ while the SOA 32 is not driven and the laser light L is not incident on the power monitor PD 34. Specifically, the power monitor PD 34 detects the power of the stray light L ₀ immediately after starting the wavelength tunable laser assembly 100, switching the DFB laser stripes 31-1 to 31-n, or in the same DFB laser stripe. This is also performed when the so-called output wavelength of the laser beam L is switched, such as when the wavelength is changed by changing the temperature of the laser.

  In the first embodiment, detection of abnormality of the drive current output from the SOA drive circuit 50 is performed as follows.

  That is, the guided laser beam emitted from the DFB laser unit 31 is amplified by the SOA 32 and emitted as the laser beam L. Here, the output power of the laser light L amplified by the SOA 32 changes according to the magnitude of the drive current output from the SOA drive circuit 50 and supplied to the SOA 32. The power monitor PD 34 can detect whether the drive current supplied from the SOA drive circuit 50 to the SOA 32 is normal or abnormal by detecting the laser light L emitted from the SOA 32. .

  Specifically, first, the CPU 20 preliminarily monitors the monitor value by the current monitor circuit 60 based on the monitor value of the laser light L by the power monitor PD 34 when the drive current value output from the SOA drive circuit 50 is normal. Is held as a target value. Then, the CPU 20 calculates a difference between the monitor value monitored by the current monitor circuit 60 according to the monitor value of the laser light L of the power monitor PD 34 and the held target value. When this difference becomes greater than or equal to a predetermined upper limit value or less than a predetermined lower limit value, the CPU 20 determines that the current value of the drive current output from the SOA drive circuit 50 is abnormal. Thereby, the CPU 20 can detect an abnormality in the drive current output from the SOA drive circuit 50. Then, the CPU 20 controls the SOA drive circuit 50 via the DAC 22 so that the current value output from the SOA drive circuit 50 becomes a normal current value.

(Conventional tunable laser assembly)
Here, in order to facilitate understanding of the effect of the abnormal current detection method in the wavelength tunable laser assembly 100 according to the first embodiment of the present invention, a wavelength tunable laser assembly according to the prior art will be described. FIG. 3 is a schematic diagram showing a configuration of a wavelength tunable laser assembly 200 according to the prior art, and FIG. 4 is a schematic diagram showing a configuration of another wavelength tunable laser assembly 300 according to the prior art.

  As shown in FIG. 3, the tunable laser assembly 200 according to the related art includes a CPU 20, a laser module 30, a DFB drive circuit 40, an SOA drive circuit 50, and a printed circuit board 10, as in the first embodiment described above. And a current monitor circuit 60 are provided at predetermined positions. On the other hand, unlike the first embodiment, in addition to the current monitor circuit 60, the wavelength tunable laser assembly 200 includes a current monitor circuit 61 that monitors the drive current supplied from the SOA drive circuit 50 to the SOA 32, and the DFB drive circuit 40. And a current monitor circuit 62 for monitoring the drive current supplied to the DFB laser unit 31 are provided at predetermined positions. In addition to the DACs 21 and 22 and the ADC 23, the CPU 20 includes an ADC 24 for inputting a signal output from the current monitor circuit 61 to the CPU 20 and an ADC 25 for inputting a signal output from the current monitor circuit 62 to the CPU 20. Furthermore, it is provided. Here, the DACs 21 and 22 and the ADCs 23 to 25 are built in the CPU 20, but may be provided as IC chips on the printed circuit board 10 outside the CPU 20.

  Thus, in the conventional wavelength tunable laser assembly 200, the current monitor circuits 61 and 62 monitor the drive currents output from the SOA drive circuit 50 and the DFB drive circuit 40, respectively, and supply those monitor values to the CPU 20. To do. The CPU 20 calculates the difference between the monitor value monitored by the current monitor circuit 61 and the target value held in advance. When this difference becomes greater than or equal to a predetermined upper limit value or less than a predetermined lower limit value, the CPU 20 determines that the drive current output from the SOA drive circuit 50 is abnormal. Further, the CPU 20 determines whether or not the drive current output from the DFB drive circuit 40 is abnormal, similarly to the case of the SOA drive circuit 50, using the monitor value monitored by the current monitor circuit 62. Thereby, the CPU 20 can detect an abnormality in the drive current output from the SOA drive circuit 50 and the DFB drive circuit 40.

  As shown in FIG. 4, another wavelength tunable laser assembly 300 according to the prior art is similar to the wavelength tunable laser assembly 200 described above, on the printed circuit board 10 is a CPU 20, a laser module 30, a DFB drive circuit 40, and an SOA drive. The circuit 50 and the current monitoring circuits 60 to 62 are provided at predetermined positions, respectively, and the CPU 20 includes DACs 21 and 22 and ADCs 23 to 25. Here, the DACs 21 and 22 and the ADCs 23 to 25 are built in the CPU 20, but may be provided as IC chips on the printed circuit board 10 outside the CPU 20.

On the other hand, the wavelength tunable laser assembly 300 differs from the wavelength tunable laser assembly 200 described above in that a photodiode (PD) 35 is further provided in the laser module 30. In the PD 35, the DFB laser unit 31 detects the laser light L _b emitted from the rear end surface to the side opposite to the installation side of the SOA 32. The PD 35 outputs a current corresponding to the detected power of the laser beam L _b and supplies it to the current monitor circuit 62. That is, the current monitor circuit 62 in the wavelength tunable laser assembly 300 uses the output power of the laser beam L _b emitted from the DFB laser unit 31 instead of monitoring the drive current supplied to the DFB laser unit 31 by the DFB drive circuit 40. In response, the current output by the PD 35 is monitored.

  In the wavelength tunable laser assembly 300, as in the wavelength tunable laser assembly 200, the current monitor circuit 61 monitors the drive current output from the SOA drive circuit 50 and supplies the monitored value to the CPU 20. Then, the CPU 20 determines whether or not this drive current is abnormal.

On the other hand, the current monitor circuit 62 monitors the current output from the PD 35 according to the power of the laser beam L _b emitted from the DFB laser unit 31 and supplies the monitored value to the CPU 20. When the current output from the PD 35 becomes equal to or higher than a predetermined upper limit value or lower than a predetermined addition / subtraction value with respect to the target value in the normal state, the CPU 20 causes the DFB drive circuit 40 to change the DFB laser unit 31. Is determined to be abnormal.

  As described above, in the conventional wavelength tunable laser assemblies 200 and 300, the current monitor circuit 62 for monitoring the drive current supplied to the DFB laser unit 31 by the DFB drive circuit 40 in order to detect an abnormality in the drive current. And the current monitor circuit 61 for monitoring the drive current supplied from the SOA drive circuit 50 to the SOA 32 is necessary. Therefore, in the wavelength tunable laser assembly, if these current monitor circuits 61 and 62 are not necessary, the size can be reduced by the installation area of the current monitor circuits 61 and 62. Further, in order to supply monitor values as monitor information from the current monitor circuits 61 and 62 to the CPU 20, the ADCs 24 and 25 are also required for the CPU 20. These ADCs 24 and 25 may be built in the CPU 20 or provided externally, but in either case, if the current monitor circuits 61 and 62 are not required, the ADCs 24 and 25 need not be provided. The area occupied by the CPU 20 can be reduced.

According to the first embodiment described above, the power monitor PD 34 detects the power of the stray light L ₀ emitted by the DFB laser unit 31, so that the drive current supplied by the DFB drive circuit 40 to the DFB laser unit 31 is detected. By detecting the abnormality, it is possible to detect the abnormality of the drive current output from the DFB drive circuit 40 without providing a current monitor circuit for monitoring the drive current output from the DFB drive circuit 40. Therefore, in the wavelength tunable laser assembly 100 in which the laser module 30 having the DFB laser unit 31 is mounted, the occupied area is reduced by the amount of the current monitor circuit that monitors the drive current output from the DFB drive circuit 40, and the size is reduced. Can do.

  Furthermore, in the first embodiment, the power monitor PD 34 detects the power of the laser light L emitted from the SOA 32, thereby detecting an abnormality in the drive current that the SOA drive circuit 50 supplies to the SOA 32. Therefore, it is not necessary to provide a current monitor circuit for monitoring the drive current output from the SOA drive circuit 50, and the occupied area can be further reduced, and the wavelength tunable laser assembly 100 can be further miniaturized. Specifically, the current monitor circuits 62 and 61 for monitoring the drive currents of the DFB drive circuit 40 and the SOA drive circuit 50 are not required, so that the control circuit in the conventional wavelength tunable laser assemblies 200 and 300 is controlled. It was confirmed that the occupied area of the circuit on the printed circuit board 10 can be reduced by about 3% or more, and a total of about 6% or more.

  Furthermore, in the wavelength tunable laser assemblies 200 and 300 cited as the prior art in the first embodiment, the DACs 21 and 22 and the ADCs 23 to 25 are described as examples built in the CPU 20, but as described above. Further, it can be assumed that the DACs 21 and 22 and the ADCs 23 to 25 are provided as individual circuits (IC chips) on the printed circuit board 10 outside the CPU 20. In this case, the ADCs 24 and 25 individually occupy areas on the printed circuit board 10. As a result, when the ADCs 24 and 25 need not be provided as in the wavelength tunable laser assembly 100 according to the first embodiment described above, the portion occupied by the ADCs 24 and 25 made of IC chips can be reduced, and the occupied area can be reduced. can do. Therefore, according to the first embodiment, it is possible to further reduce the occupied area of the control circuit on the printed circuit board 10 as compared with the prior art.

  Next, a second embodiment of the present invention will be described. FIG. 5 shows a wavelength tunable laser assembly as an optical integrated device assembly according to the second embodiment.

  As shown in FIG. 5, the wavelength tunable laser assembly 101 according to the second embodiment has a current monitor circuit 61 for monitoring the drive current supplied to the SOA 32 by the SOA drive circuit 50, unlike the first embodiment. Is provided. A drive current supplied from the SOA drive circuit 50 to the SOA 32 is branched and supplied to the current monitor circuit 61. Further, the CPU 20 is provided with an analog / digital conversion unit (ADC) 24 for inputting a current signal output from the current monitor circuit 61.

  The abnormal current detection method in the wavelength tunable laser assembly 101 differs from the first embodiment in that the current monitor circuit 61 monitors the drive current supplied from the SOA drive circuit 50 to the SOA 32 and supplies this monitor value to the CPU 20. To do. As a result, the CPU 20 can calculate the difference between the monitor value by the current monitor circuit 61 and the target value held in advance in the drive current, and the drive current output by the SOA drive circuit 50 based on this difference. It can be determined whether or not is abnormal. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

  According to the second embodiment, the same effects as those of the first embodiment can be obtained. Specifically, the current monitor circuit 62 for detecting an abnormality in the drive current of the DFB drive circuit 40 is not required for the control circuit of the conventional wavelength tunable laser assemblies 200 and 300 described above, and thus the printed circuit board 10. It was confirmed that the area of the upper control circuit can be reduced by about 3% or more.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, Various deformation | transformation based on the technical idea of this invention is possible. For example, the configurations of the CPU and laser module described in the above-described embodiment are merely examples, and different CPUs and laser modules may be adopted as necessary.

  Further, the laser light output detecting means according to the present invention can be applied to the wavelength variable laser assemblies 200 and 300 according to the prior art. In this case, since the detection means for detecting the drive current abnormality in the semiconductor laser can be duplicated, the detection performance related to the drive current abnormality can be further improved.

10 Printed circuit board 20 CPU
21, 22 Digital-analog converter (DAC)
23, 24, 25 Analog-digital converter (ADC)
30 Laser module 31 Distributed feedback laser unit (DFB laser unit)
31-1 to 31-n DFB laser stripes 31a-1 to 31a-n Optical waveguide 31b MMI optical combiner 31c Trench groove 31d Output port 31e End face 32 Optical amplifier (SOA)
32a output end 33 beam splitter 34 power monitor photodiode (power monitor PD)
35 Photodiode (PD)
40 DFB drive circuit 50 SOA drive circuit 60, 61, 62 Current monitor circuit 100, 101, 200, 300 Tunable laser assembly L, L _b Laser light L ₀ Stray light

Claims (4)

A leakage light detection step of detecting leakage light that is not guided in the optical integrated element of the laser light by a laser light output detection means that detects the output of the laser light emitted from the optical integrated element having a semiconductor laser;
An abnormality detecting step of detecting an abnormality of the drive current of the semiconductor laser by the control means based on the intensity of the leaked light detected by the laser light output detecting means. Current detection method.   The semiconductor laser is a distributed feedback semiconductor laser, and the laser light output detecting means is configured to detect the laser light amplified by an optical amplifying means for amplifying the laser light emitted from the semiconductor laser. The method for detecting an abnormal current of an optical integrated device according to claim 1. An optical integrated device having a semiconductor laser;
Laser light output detection means configured to be able to detect laser light guided in the optical integrated element out of the laser light emitted from the optical integrated element and leakage light not guided in the optical integrated element;
Based on the intensity of the leakage light detected by the laser light output detection means, control means configured to be able to detect an abnormality in the drive current of the semiconductor laser;
An optical integrated device assembly comprising:   A plurality of semiconductor lasers configured such that the optical integrated element can emit laser beams having different wavelengths; and a plurality of optical waveguides configured to be able to guide laser beams emitted from the plurality of semiconductor lasers, respectively. An optical combiner configured to be able to combine the laser light guided by the plurality of optical waveguides and a semiconductor optical amplifier that amplifies the laser light output from the optical combiner. The optical integrated device assembly according to claim 3.

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