The visible emitter is composed of input interface, light source, driving circuit, monitoring circuit, control circuit, etc. The core of the visible emitter is light source and driving circuit. In digital communication, the input circuit shapes the input signal (such as PCM pulse), transforms it into a code suitable for transmission on the line, and then drives the circuit light source, or sends it to the optical modulator to modulate the continuous light wave output of the light source. In order to stabilize the average optical power output and operating temperature, an automatic temperature control and power control circuit is usually set up.
