DIGITAL CONNECTION
A Simple Short-Distance Communication Path Using Light
This month we’ll take a look at a somewhat unconventional kind of digital data link, using a 461-THz transmitter and compatible receiver. This has been done before (including by me), so we’re not breaking any new ground here, but if you like to play around and have a limited budget, the basic idea can be adapted to many different uses.
The short version is that it’s a laser link. The inexpensive laser module that I used can be modulated at a higher frequency than I can easily measure, well above the audio range, and capturing the light signal cannot be easier. While I have not measured the ultimate range, I speculate it is at least a few hundred feet at worst.
The reasoning behind all this effort is twofold; First, to see if a laser could be used to establish a short link between my house and the garden shed equipment I plan to house in there. Second, to show how a simple circuit can be used as a communications link, perhaps for the next microwave contest — not much competition on the 400-THz band. I was inspired by an article in the April 2015 issue of by Irwin Math, WA2NDM, for a kilowatt optical
