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When I see a big radio antenna, I like to imagine it's a giant incandescent light bulb filament in the vertical, but of a invisible light. So that it "glows" the radio, performing oscillations which contains all the music/voice information.

But at the reverse, is it possible to create a practical experiment which modulates (or something) an analog audio signal and transmits it by glowing some sort of light, then have a antenna or sensor to pick it up and reproduce the signal to a speaker?

Is it possible to use a mono pole antenna to detect light?

fschuindt
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But at the reverse, is it possible to create a practical experiment which modulates (or something) an analog audio signal and transmits it by glowing some sort of light, then have a antenna or sensor to pick it up and reproduce the signal to a speaker?

Yes, in principle.

Analog modulation of optical signals is not super common, but it is done, for example in many CATV-over-optical-fiber systems.

Free-space optical communication is commonly be done between a hand-held remote control and a television set.

Optical communication of audio signals is done in TOSLINK interconnect.

There's no technological reason these things aren't all combined into a single analog, free-space, audio communication system, only economic reasons: We have cheaper ways of doing it so nobody has bothered to commercialize such a thing.

It would be pretty easy to set up a class-room demonstration where an audio signal is sent to an LED, which illuminates a photodiode a few cm away, which connects through an amplifier to drive a speaker, if you wanted to demonstrate such a thing.

Even with much older technology, there was the photophone developed by Alexander Graham Bell.

The Photon
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Various spy agencies have used this technique to eavesdrop on conversations from some distance away. When people are talking inside a room that has windows, there is a very tiny vibration of the windows as the sound waves from the voices bounce off of those windows. It is possible to reflect a laser beam off of a vibrating window, receive the reflected beam, and recover the sound waves from the modulation contained in that beam.

David White
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