| 摘要 |
PURPOSE:To prevent the deterioration of characteristics due to the light retrogressing to laser for the titled sweeping layer by a method wherein the detector, which detects the phase difference between a laser output light and the light retrogressing to laser, is provided on the output optical path of the semiconductor laser with wavelength sweeping function, and a phase shifter with which a phase shift is generated is provided in proportion to the laser output. CONSTITUTION:A phase difference detector 1-20, to be used to detect the phase difference between the laser output light and the retropressing light, is provided on the output optical path of semiconductor laser 1-40 of the semiconductor laser 1-10 having wavelength sweeping function. The detector 1-20 consists of a beam splitter 1-22, a reflecting mirror 1-23 and a detector 1-21, and also an electrooptical effect type phase shifter 1-30 is arranged at the latter stage of the above. With the constitution above- mentioned, the phase difference between the laser output light and the retrogressing light is detected by the detector 1-20, the signal of the detected result is transferred to a phase shifter 1-30, the phase of the retrogressing light is controlled by the phase shifter 1-30, and the above is turned to the same phase as the laser output light. Accordingly, the output distortion of the laser light is eliminated, and at the same time, the generation of the excessive noise and the fluctuation of wavelength can be prevented. |
