Inspection method for semiconductor laser device and inspection device for semiconductor laser device

1 . An inspection method for semiconductor laser device adapted to inspect a semiconductor laser device integrated with a semiconductor laser, an electroabsorption modulator configured to receive as an input a laser light output from the semiconductor laser, and a photodetector fixed in a single position to detect a laser light intensity of a part of the laser light of the semiconductor laser output from the electroabsorption modulator, the inspection method comprising:

a step of acquiring a transverse-mode light output characteristic that is a relationship between an injection current to the semiconductor laser and a photocurrent output from the photodetector;

a step of applying a reverse bias voltage to the electroabsorption modulator and acquiring a total light output characteristic that is a relationship between the injection current to the semiconductor laser and a photocurrent output from the electroabsorption modulator while applying the reverse bias voltage to the electroabsorption modulator; and

a step of comparing the total light output characteristic with the transverse-mode light output characteristic, and; and

a step of determining whether or not the semiconductor laser device under inspection is abnormal in a transverse mode based on a result of comparing the total light output characteristic with the transverse-mode light output characteristic.

2 . The inspection method for semiconductor laser device, of claim 1 , wherein the semiconductor laser device under inspection has a window structure at a front end surface of the semiconductor laser device, and the photodetector is disposed at a position for receiving the part of the laser light diverging in the window structure.

3 . The inspection method for semiconductor laser device, of claim 2 , wherein the step of comparing includes comparing a number of local extrema of a characteristic curve of the transverse-mode light output characteristic with a number of local extrema of a characteristic curve of the total light output characteristic.

4 . The inspection method for semiconductor laser device, of claim 2 , wherein the step of comparing includes comparing a position of the injection current of a local extremum of a characteristic curve of the transverse-mode light output characteristic with a position of the injection current of a local extremum of a characteristic curve of the total light output characteristic.

5 . The inspection method for semiconductor laser device, of claim 2 , further comprising calculating products of derivative values of a characteristic curve of the transverse-mode light output characteristic and derivative values of a characteristic curve of the total light output characteristic, and the step of determining includes determining whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on the products.

6 . The inspection method for semiconductor laser device, of claim 1 , wherein the semiconductor laser device under inspection has a window structure at a rear end surface of the semiconductor laser device, and the photodetector is disposed at a position for receiving the part of the laser light diverging in the window structure.

7 . The inspection method for semiconductor laser device, of claim 6 , wherein the step of comparing includes comparing a number of local extrema of a characteristic curve of the transverse-mode light output characteristic with a number of local extrema of a characteristic curve of the total light output characteristic.

8 . The inspection method for semiconductor laser device, of claim 6 , wherein the step of comparing includes comparing a position of the injection current of a local extremum of a characteristic curve of the transverse-mode light output characteristic with a position of the injection current of a local extremum of a characteristic curve of the total light output characteristic.

9 . The inspection method for semiconductor laser device, of claim 6 , further comprising calculating products of derivative values of a characteristic curve of the transverse-mode light output characteristic and derivative values of a characteristic curve of the total light output characteristic, and the step of determining includes determining whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on the products.

10 . The inspection method for semiconductor laser device, of claim 1 , wherein the step of comparing includes comparing a number of local extrema of a characteristic curve of the transverse-mode light output characteristic with a number of local extrema of a characteristic curve of the total light output characteristic.

11 . The inspection method for semiconductor laser device, of claim 1 , wherein the step of comparing includes comparing a position of the injection current of a local extremum of a characteristic curve of the transverse-mode light output characteristic with a position of the injection current of a local extremum of a characteristic curve of the total light output characteristic.

12 . The inspection method for semiconductor laser device, of claim 1 , further comprising calculating products of derivative values of a characteristic curve of the transverse-mode light output characteristic and derivative values of a characteristic curve of the total light output characteristic, and the step of determining includes determining whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on the products.

13 . An inspection device for semiconductor laser device configured to inspect a semiconductor laser device integrated with a semiconductor laser, an electroabsorption modulator configured to receive as an input a laser light output from the semiconductor laser, and a photodetector fixed in a single position to detect a laser light intensity of part of the laser light of the semiconductor laser output from the electroabsorption modulator, the inspection device comprising:

a semiconductor laser power source configured to supply an injection current to the semiconductor laser;

an electroabsorption modulator power supply configured to supply a reverse bias voltage to the electroabsorption modulator;

a photodetector power supply configured to supply a reverse bias voltage to the photodetector, and

an inspection controller configured to acquire a transverse-mode light output characteristic that is a relationship between the injection current to the semiconductor laser and a photocurrent output from the photodetector and to acquire a total light output characteristic that is a relationship between the injection current to the semiconductor laser and a photocurrent output from the electroabsorption modulator while applying the reverse bias voltage to the electroabsorption modulator, and to compare the total light output characteristic with the transverse-mode light output characteristic, thereby to determine whether or not the semiconductor laser device under inspection is abnormal in a transverse mode.

14 . The inspection device for semiconductor laser device, of claim 13 , wherein the inspection controller is configured to compare a number of local extrema of a characteristic curve of the transverse-mode light output with a number of local extrema of a characteristic curve of the total light output characteristic, and determine whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on a result of comparing the number of local extrema of the characteristic curve of the transverse-mode light output with the number of local extrema of the characteristic curve of the total light output characteristic.

15 . The inspection device for semiconductor laser device, of claim 13 , wherein the inspection controller is configured to compare a position of the injection current of a local extremum of a characteristic curve of the transverse-mode light output characteristic with a position of the injection current of a local extremum of a characteristic curve of the total light output characteristic, and determine whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on a result of comparing the position of the local extremum of the characteristic curve of the transverse-mode light output characteristic with the position of the local extremum of the characteristic curve of the total light output characteristic.

16 . The inspection device for a semiconductor laser device, of claim 13 , wherein the inspection controller is configured to calculate products of derivative values of a characteristic curve of the transverse-mode light output characteristic and derivative values of a characteristic curve of the total light output characteristic, and determine whether or not the semiconductor laser device under inspection is abnormal in the transverse mode based on the products.

17 . An inspection method for semiconductor laser device adapted to inspect a semiconductor laser device integrated with a semiconductor laser and an electroabsorption modulator configured to receive as an input a laser light output from the semiconductor laser, the inspection method comprising:

a step of acquiring a transverse-mode light output characteristic that is a relationship between an injection current to the semiconductor laser and a photocurrent output from a photodetector fixed in a single position to detect a laser light intensity of a part of the laser light of the semiconductor laser output from the electroabsorption modulator;

a step of applying a reverse bias voltage to the electroabsorption modulator and acquiring a total light output characteristic that is a relationship between the injection current to the semiconductor laser and a photocurrent output from the electroabsorption modulator while applying the reverse bias voltage to the electroabsorption modulator;

a step of comparing the total light output characteristic with the transverse-mode light output characteristic; and

a step of determining whether or not the semiconductor laser device under inspection is abnormal in a transverse mode based on a result of comparing the total light output characteristic with the transverse-mode light output characteristic.