Linear & Nonlinear Frequency Converters

A. Linear Frequency Converters 1. Erbium 1.73 μm-pumped KI Laser between 2-4 μm Previously,1 we reported laser action for the lithium (F2+)A center in KI in which tuning was achieved from 2.59 to 3.65 μm. With more experimental improvements, we reported (F2+)A-center tunability ranging from 2.38 to 3.99 μm. Furthermore, with the addition of F2+ centers coexisting with (F2+)A centers, the combined range of continuous tuning extends below 2 μm, spanning almost an entire octave. The 1.73-μm line from a pulsed Er:LiYF4 (YIE) laser was used as a pump source for both centers. The F2+ center consists of an electron trapped by an adjacent pair,2-5 and the (F2+)A center consists of an F2+ center next to a substitutional cation impurity, such as Li+.6-7