Optical communication module using LED and photodiode or sensors
The major challenge with communicating with light is interference from the SUN or 60Hz room lighting or 80,000Hz electronic-ballast fluorescent lights.

Sending a coded optical tone ----- 38KHz ----- is the simple and robust method.

You can recovery these tones using NE567 tone decoder, which provides a logic output upon arrival of a "strong tone". You will need to DC_block the input signal.

http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf







simulate this circuit &ndash; Schematic created using CircuitLab

The dual Rload, with Diode(s), allows high current operation at high photon fluxes.