Some JA1ATI LASER optical communications experiments:

• this is the transmitter (10k) physical layout drawing
• this is the transmitter (10k) regulator/CW keyer schematic
• the chopper modulator (35k) is formed simply by a small DC fan
• here is a photo of the modulation (32k) waveform on an oscilloscope
• this is the receiver (14k) schematic diagram