The LASER transmitter/receiver project uses inexpensive parts to accomplish optical communication.
The LASER transmitter/receiver project by Samer Muhi can be used to send audio using an inexpensive laser beam. Muhi used frequency modulation to reduce the amount of interference caused by ambient light and changes in transmitter intensity.
Hacked Gadgets has more on the project
This project demonstrates the use of laser in optical communications. The project consists of a transmitter and receiver that will support a one-way communications link between two separate locations. It is mainly built from a few ICs, operational amplifiers and transistors. It is possible to transmit music, voice and data. The laser used in the transmitter is a simply a laser diode that it used in cheap laser pointers and at the receiver, the laser sensor is a photo-diode.
Watch a video demo below: