[Laser] Ultrasonic Modulator?

[KD7JYK, 49H7KR]

I am looking for a circuit where I can mix a VFO from around 10 - 30 KHz
with a microphone.  Nothing fancy, AM OK.  This group is as close as I can
think of for this project, I want to super-impose my voice on an ultrasonic
carrier and send it a distance using some high power tweeters I have.  I
have tracked down numerous sources of amplifiers that will cover this audio
range up to several tens of Watts, looking for a modulator.

Any ideas?

Kurt