What is an optical transmitter?
An optical transmitter is any device that sends information in the form of light.
Transmission of information can be done in many ways. An optical transmitter is one half of a communications system, where the other half would be an optical receiver.
Generating an optical signal is the job of the optical transmitter, which encodes the information to be transmitted on the light that it generates. This is very similar to other transmission methods that use electrical signals, e.g. Ethernet or USB cables, or radio transmissions like AM or FM radio.
Optical transmission falls into one of two categories. Guided-wave or free-space. The most common guided wave optical transmission system uses fiber optic cable. Light is transmitted through the fibre which uses total internal reflection to keep the light trapped inside.
The simplest optical transmitter is one that sends binary data, ones and zeros, encoded as the presence or absence of light.
A free space optical system would be much the same except that the transmitter and receiver would be separated by some distance and have line of sight to each other. In this case the light would propagate through the air.