Air to Ground Optical Communications Link based on Retromodulator

This project analyzes and implements an optical-communication downlink based on a remote aerial terminal to a ground station. The ground station acts as a receiver and houses the laser source that shines on the remote terminal, which acts as a transmitter. The retromodulator onboard the transmitter, modulates the incident laser signal using liquid crystal cells, after reflecting it upon the same direction of arrival. The modulation consists of inducing different phase delays in the different components of the electric field of the laser signal in order to obtain different polarization states as symbols in which to encode information.