Well, the semantics of what constitutes light and what not are a bit murky. CO2 lasers are still considered LIGHT amplification by stimulated emission of radiat

Well, the semantics of what constitutes light and what not are a bit murky. CO2 lasers are still considered LIGHT amplification by stimulated emission of radiation. CO2 lasers operate at ~10000nm. In the optics community we usually consider everything we can manipulate with refractive optics as "light" – and yes, I am fully aware that this goes down well into what's considered microwave radio. My personal cutoff for where optics begins is, where I no longer can use an antenna that is part of a resonant _circuit_ to emit / receive the radiation, and have to resort to quantum mechanical state transitions.