This is our prototype. The lights are the input signal and the box is all of the photochromic transistors together. The different colours are the different characters of the hexadecimal system. Due to the fact that the visible spectrum is only a small portion of the electromagnetic spectrum, it is very likely that the crystals will operate in a frequency range that is outside the visible spectrum. However, IR lights are rather boring to us since we can't see them, thus the pretty colours.