Color Center Lasers

Color centers - electrons trapped by defects in insulating crystals - can be used to make optically pumped lasers, broadly tunable over various bands in the ultraviolet, the visible, and most importantly, in the 0.8-4microns range of the infrared. Almost all are capable of cw and cw-model-locked operation. In this chapter, the background color-center physics is surveyed, and laser construction and performance are detailed. Included is the soliton laser, a color-center laser whose mode-locked pulses, controlled by the length of optical fiber in its feedback loop, can be as short as a few tens of femtoseconds.