| 摘要 |
PURPOSE:To secure a stable repeating and amplificaion output by monitoring optical power incident to and emitted from a semiconductor optical amplifier and then by forming a feedback loop for an applied current and operation temperature so that an amplifier gain is constant at any time by the optical power. CONSTITUTION:An incident beam is branched by a beam splitter 1 and then amplified by an optical amplifier 3 after passing through a lens 2; and it is made by an output lens 4 into parallel light, which is transmitted to the next transmission line via a beam splitter 5. The incident beam branched by the splitter 1 is applied to a photodetector 6 and an electric output proportional to incident beam intensity is applied to an amplifier 8', whose output is inputted to a differential amplifier 8. Part of the output beam branched by the splitter 5, on the other hand, is applied to a photodetector 7 and its electric output proportional to output beam intensity is applied to the amplifier 8 as well. Then, incident optical power to and emitted optical power from the amplifier 3 are monitored by the differential amplifier 8 to hold the amplification gain constant at any time, thereby securing the stability of a repeating and amplification output. |
