Hello,

Hope you are doing good.

Optical communication is the use of the optical portion of EM spectrum (UV, Visible, Infrared) for communication. Optical communication can be wired as well as wireless.

There is a transmitter(generally a laser or LED) that emits in the desired range of frequencies which are modulated with the data  and then the medium (wired: fibre, wireless: freespace) through which the optical signals are transmitted and a receiver to receive the optical signals.

Hope this helps

Good Luck