I wonder how this links in to optical crystals? KTP, used in solid state lasers, will halve the frequency of a IR laser (1064nm) to produce green light (532nm).
I suppose this is equivalent to adding electrical energy to a crystal to make it oscillate.
532 nm corresponds to double the frequency of 1064 nm, not half. Any nonlinear response generates harmonics of a signal but not subharmonics. This is why in electronics a single diode can be used as a frequency doubler, but a digital flip-flop is required for frequency division.
