6533b854fe1ef96bd12ae848

RESEARCH PRODUCT

Thermal expansion, normalized thermo-optic coefficients, and condition for second harmonic generation of a Nd:YAG laser with wide temperature bandwidth in RbTiOPO_4

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Interferometric determination of thermal expansion and of normalized thermo-optic coefficients of RbTiOPO4 at four laser wavelengths are performed as a function of temperature. A suitable vectorial formalism applied to obtained data allows the establishment of the temperature dependence of refractive indices, and subsequent theoretical analysis enables one to predict that an extremum in the evolution of the phase-matching direction in the (X,Y) plane should occur near 100 °C for type II second harmonic generation of Nd:YAG lasers, with a temperature bandwidth that can be as large as 117 °C for a crystal of 10 mm in length. Such unusual behavior is observed experimentally by recording the conversion efficiency from 20 °C up to 220 °C for various propagation angles of light in the (X,Y) plane. Slight quadratic temperature dependence of the effective nonlinear coefficient is also observed.