Optical damage thresholds reported for frequency-doubling 1.06-µm light in KTiOPO4 (KTP) range from 1–>30 GW/cm2, depending on the experimental details and the type of crystal tested. KTP crystals are grown by flux and high- and low-temperature hydrothermal techniques. Damage thresholds of hydrothermal crystals have been observed to be higher than those of flux- grown KTP. One type of damage observed in KTP crystals in the formation of gray tracks or thin regions of darkened material. Gray tracks are dichroic and preferentially absorb light on the electric vector along the z-axis. Continued operation after gray-track formation quickly leads to catastrophic failure, because both fundamental and second-harmonic light are absorbed.

© 1991 Optical Society of America

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