Podder, Susmita and Nath, Aparajita Mallick and Mukherjee, C and Subrahmanyam, V V V and Jana, Sunirmal
(2022)
Fabrication and characterization of sol-gel-based coatings on quartz glass to obtain antireflective effect at 1054 nm for optics of high power Nd:phosphate glass laser.
Bulletin of Materials Science, 45 (3).
Art No-154.
ISSN 0250-4707
Abstract
In order to obtain higher laser-induced damage threshold (LIDT) and lower loss of laser radiation, the incident radiation must have an insignificant absorbance and high anti-reflectance. In this work, a single-layer porous SiO2-based anti-reflective (AR) coating for the optics of Nd:phosphate laser system has been developed on quartz glass optics adopting sol-gel dip coating technique, following quarter wavelength optical design. As measured by spectroscopic ellipsometer, the refractive index (RI) of the coated layer is found to be similar to 1.2. A maximum transmittance of similar to 99% in single-layer-coated quartz glass has been achieved at 1054 nm. In addition, the non-quarter wavelength-based double layer with an optical design (glass/ 0.7153 M / 1.134 L / air) and triple-layer AR coating with an optical design (glass / 0.28 H / 1.65 M / 1.03 L / air, where H, M and L indicate one-quarter wave thick layers of high, medium and low RI materials) have been fabricated. The deposition of M and H layers has been made from mixed metal oxide precursor sols of zirconia-silica, while L has been made from silica precursor sol to obtain porous silica coating. A maximum transmittance of about 98.1 and 97.6% was found at 1054 nm in double- and triple-layer AR-coated samples, respectively. The LIDT values have been measured on the AR coatings. Based upon the number of layers in the AR coatings, the LIDT values varied in the range of 8.7-2.4 J cm(-2) starting from single to double to triple layer. The AR coatings developed by sol-gel dip coating technique could find application in Nd:phosphate high power laser system.
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