CONTINUOUS WAVE FREQUENCY DOUBLING OF A HIGH-ENERGY 1315 NM LASER

A series of extracavity frequency doubling tests were performed using the 1315 nm output from RotoCOIL, a chemical oxygen-iodine laser (COIL) at the Phillips Laboratory. LiIO3 was selected for the doubling medium due to its large nonlinear optical coefficient, low absorption, and the availability of large crystals. Tests were performed for a variety of beam sizes using 1.1 and 2.2 cm crystals. Conversion efficiencies of 8% were achieved resulting in visible (657 nm) CW power levels of nearly 700 W. Catastrophic crystal failure occurred after a 1 s exposure to a focused beam of 6770 W.