| 摘要 |
PURPOSE:To realize a long-distance communication and to improve the noise resistance, by inducing a relaxation oscillation having a certain frequency and light intensity to transmit an output after a modulation of amplitude and then receiving the output by a receiver that can perform simultaneously both a photodetection and amplification by means of an avalanche photodiode. CONSTITUTION:The output of an external standard reference frequency source 10 is applied to a comparison detector 11 along with an electric output 6, and a DC output is fed back in the form of a DC bias of a semiconductor laser 1 through a coupler 9 to stabilize the frequency. At the same time, the output intensity is detected by a wave detector 2, and then a variable attenuator is controlled to keep the optical output intensity at a certain level. Then the output optical pulse train is transmitted after receiving a modulation of amplitude through an external modulator 13. At a receiver, a signal light 33 is made incident to an avalanche photodiode 32 in a coaxial-type resonance cavity device 31, and a reproduced signal is obtained through a wave detector 34. |
