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Gamma Ray Processing of ZnGeP2: A Nonlinear Optical Material for the Infrared
Published online by Cambridge University Press: 21 February 2011
Abstract
Zinc germanium phosphide, an important frequency-conversion material for producing mid-infrared lasers, is plagued by a defect-related absorption band extending from the fundamental edge (0.62 microns) to ∼3 microns. The level of absorption varies with melt composition, and can be reduced by post-growth annealing treatments. In these experiments, further reduction of the near-band-edge absorption was achieved by irradiating with 1.173 MeV and 1.3325 MeV gamma rays. A 40 kiloCurie “Co source was used to irradiate a series of crystals at an average flux of 4.8x10s rads/hr to cumulative doses up to 3.91xl010 rads. The absorption coefficient in the near-infrared was reduced by nearly a factor of two, and the penetration depth of the ionizing radiation was sufficient to uniformly reduce the absorption in the largest samples tested (up to 7x8x23mm3). The loss coefficients achieved at 1 micron (4.28cm∼l) and at 2.05 microns (0.19cm1) are lower than the best results achievable by conventional thermal annealing alone. No saturation effects or absorption increases at longer wavelengths were observed.
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- Copyright © Materials Research Society 1995
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