I've done a project like this some years ago. But I transmitted analog signals instead of digital
It's pretty easy really. What I did before was I connect a laser pointer to the audio-out of a radio, and an LDR to the audio-in of an amplifier. I can't really remember the exact circuitry, but it was probably just some transistors for a bit of amplification etc.
This setting worked perfectly indoors. The furtherst I tested indoors was like 5 metres, and there was very little noise.
I tried to do it outdoors during a party we had, but the laser beam was too small to see from a few metres. I had a really hard time trying to focus the beam exactly on the LDR. Since a party is not a party without music, I had to cancel my experimentation after a few minutes of trying
I remembered seeing some tutorials on the web. There was this guy who managed to get his system working across the street. But he used a really big laser.
Found this: http://www.instructables.com/id/Send-Music-over-a-Laser-Beam/