ABSTRACT
Transmitters serve to convert electrical inputs into a form suitable for transmission down a line. In fiber optics, the transmitter performs two functions: turning the input signal into a diode drive current, and converting that current into an optical signal. The transmitter converts electrical signals into modulated optical signals, which are then coupled into the fiber. The receiver converts the optical signal back into an electrical signal, amplifies and demodulates it, and filters it to improve the signal–to–noise ratio or bit error rate. In the early 1970’s, transmitters were generally made from discrete devices. In the later 1970’s, many transmitters were assembled in hybrid modules containing ICs, discrete resistors and capacitors, and optical source diodes. In the 1980’s, transmitter complexity and communication speeds increased. Many fiber optic links are used to interconnect computers and peripherals. The light emitting diode and laser diode have electrical characteristics similar to those of other diodes.
