Some time ago, I constructed a small unidirectional communication system using a laser. I connected an Arduino to a laser, and other Arduino to a LDR sensor. The laser sends pulses of light, the other Arduino receives. The Arduino that emits, is connected to a netbook, and receiving Arduino is connected to a desktop computer. In the video you can see when I send the string "hola laser" (hello laser) from the netbook to the desktop.
Greetings! Sorry for the language of the video!