I've been reading about fluorescence and I understand how the band-gap accounts for reemission of photons at a longer wavelength. However, can a material store a photon, and then given an external energy source reemit at a shorter wavelength? I'm imagining an electrified "glass" that could absorb IR and reemit it in the visible spectrum. Granted, it likely wouldn't be in the same direction, but is it even possible for a material to do this? I've read about Two-photon absorption which seems like a viable process, albeit at a greatly diminished intensity. What do y'all think?