Frequency doubling in gray-track-resistant KT¥produces 165 W of green light
A high-damage-threshold gray-track-resistant (GTR) potassium titanyl phosphate (KTP) crystal has been developed by Crystal Associates (Waldwick, NJ) under a Small Business Innovation Research grant from the US Air Force Materials Directorate (Wright-Patterson AFB; Dayton, OH). According to Richard Stolzenberger at Crystal Associates, the material was made possible by "a different growth technique and not a post-treatment" after fabrication.
Researchers at TRW Space and Electronics Grou¥(Redondo Beach, CA) used GTR-KT¥to generate 165 W of frequency-doubled 532-nm green light from a diode-array-pumped Nd:YAG laser based on a phase-conjugated master-oscillator/power-amplifier architecture. Green pulses with 5 J of energy were produced at a repetition rate of 33 H¥and a conversion efficiency of 60%. Fundamental 1064-nm pulses at a repetition rate of 100 H¥had a beam quality better than 1.5 times the diffraction limit. In independent damage testing, the GTR-KT¥exhibited no laser-induced absorption after exposure to 10,000 shots of 20-ns, 532-nm pulses (at a repetition rate of 20 H¥and an energy density of 3 J/cm2).