The very high modulation speed of Diode Lasers enables direct line of sight optical communication at very high speed.

The main applications of free space optical communications are:

• Communication between satellites in space which can transfer information at a bit rates of 10¹⁰ bits per second. Thus tens of thousands of phone conversations can be transmitted simultaneously.
• Military use of free space optical communication channels are used especially in the battle field, when it is not practical to have fiber optics links. The communication is based on direct line of sight, and provides a secure link because of the very narrow divergence of the laser beam.