Wavelength dependence of repetitive-pulse laser-induced damage threshold in beta-BaB2O4.
The dependence on wavelength of repetitive-pulse (10 Hz, 8-10 ns) laser-induced damage on beta barium metaborate (BBO) has been investigated. The thresholds of dielectric breakdown in bulk crystal have been found to be 0.3 GW/cm(2) at 266 nm, 0.9 GW/cm(2) at 355 nm, 2.3 GW/cm(2) at 532 nm, and 4.5 GW/cm(2) at 1064 nm. Results indicate two-photon absorption at 266 and 355 nm, which helps to produce an avalanche effect that causes breakdown at each of the four wavelengths tested. Neither the BBO refractive indices nor the absorption spectrum change until breakdown occurs.
Kouta
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Functional Materials Research Laboratories, NEC Corporation, 1-1 Miyazaki 4-chome, Miyamae-ku, Kawasaki 216, Japan. kouta@fml.cl.nec.co.jp