Light transmission circuit

Abstract

Abstract PURPOSE:To accelerate the response of controls in a light transmission circuit having a semiconductor laser as a light source by providing a control loop for controlling the bias or amplitude of a drive signal of the light source and a control loop for controlling temperature adjusting means for the light source. CONSTITUTION:A signal applied to an input terminal 1 is converted into a current signal via a drive circuit 3, is applied to a semiconductor laser 4 together with the DC current of a bias circuit 2, and an output light is delivered from an output terminal 6 via a light branching circuit 5. The output current of a photodetector 7 for detecting the branched light is detected at its peak or averaged by a processor 8, and is applied to differential amplifiers 9, 11. The output of the amplifier 9 is applied to a bias circuit 2 to form the first negative feedback loop having fast response, the output of the amplifier 11 is applied to a temperature control element 13 thermally coupled to the laser 4, and the second negative feedback loop having higher loop gain than the first negative feedback loop is formed.

Inventors

• 👤 Takashi Shinoda

Bibliographic Details