Some years ago I was (mistakenly) looked at by recruiters from a major aerospace org. They apparently found me due to experience with public key cryptography. They somehow assumed I also had experience with laser sat to sat and sat to a/c comms & optics -- which I certainly do not. The only optics I know are straight from the notes of Mr. Newton which I learned as an undergraduate. and I'm rusty. However, they kept calling for many weeks. I hope they found their man. Anyway, it seems clear 0's and 1's are being sent via various wavelengths of laser (I will keep that part private, as I'm guessing the recruiter probably shouldn't have been yapping about it).