also that's really just a transducer, still needs a box with lasers and some other machinery that allows for demodulating that optical signal. "RF detector that doesn't contain metal" is a weird advantage because there's usually a large amount of metal connections required to actually do something useful with that freshly collected signal

30m away (that's longer than a basketball court!), though, and probably more because this demo was "no particular effort". I don't know the use case, but I'm guessing it's not a home router.