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Interaction of photo-thermo-refractive glass with nanosecond pulses at 532 nm

Photo-thermo-refractive (PTR) glass is a photosensitive silicate glass where high-efficient holographic optical elements are created for visible and near infrared spectral region. Photosensitivity of this glass is ranged down to 350 nm. Induced absorption and refraction in PTR glass were studied under consequent exposing to low power UV and high power laser radiation of second harmonic of Nd:YAG laser at 532 nm (25 mJ, 5 ns). It was found that additional absorption induced in short wavelength region by initial UV irradiation can be partially bleached by consequent irradiation at visible region. Bleaching of additional absorption was observed after high-power irradiation at 532 nm while no effect was observed after low-power illumination with the same dosage. Induced refractive index of PTR glass is higher in the area consequently exposed to UV and high-power radiation at 532 nm compare to that in the area exposed to UV radiation only. The maximal refractive index difference between single-exposed and double-exposed areas was up to 10-4. Volume Bragg grating and complex hologram were recorded in PTR glass by visible radiation at 532 nm.