I'll raise you an induction coil and leave off the battery. Or a small LED powered by a maser pointed down on the field. I mean, if you're gonna make something like that, go all out!

(Fun experiment: stick some Christmas light bulbs in the rim of a disposable bowl, fill it with a cup of water, and microwave it for a dozen seconds :)

Probably easier to just use a fluorescing material though. One might approach it as an optimization, using a scanning light to illuminate the particles, but the sound waves to keep the particle densities high where they need to be and low where no illumination is needed. It would make the apparent hologram easier to see through while maintaining brightness.

Simpler: tiny glass sphere, with RGB lasers mounted on the base tracking it and making it glow with different colors and intensities in different positions.