Experimental determination and the theoretical model of an equivalent temperature of nonlinear optical crystals interacting with high-power laser radiation

Crystal equivalent temperature model in process of nonlinear conversion of laser radiation

“…Evidently averaging depends on piezoelectric resonance selection. Model of crystal equivalent temperature for the case of uniform temperature distribution has been already introduced [4]. For accurate description of crystal real temperature averaging in course of SHG it is necessary to elaborate model of piezoelectric resonance frequency shift under strong longitudinal temperature gradient inside crystal.…”

“…When we consider interaction with laser radiation the crystal is heated due to optical absorption and commonly its temperature is nonuniformly distributed in correspondence with laser intensity profile. It was proved experimentally [2,3] and theoretically [4] that for the last case nonuniform temperature distribution can be characterized using notion of crystal equivalent temperature. Crystal equivalent temperature is directly determined from measured resonance frequency shift ΔRf n (P) caused by laser irradiation of P power taking into account prt n K value of the resonance.…”

“…As refractive indices of the crystal and therefore phase velocities of waves to a considerable extent depend on crystal temperature the last one should be accurately measured and controlled for efficient radiation conversion. Recently noncontact impedance spectroscopy method has been proposed for precise temperature measurement of nonlinear-optical crystals interacting with laser radiation [2][3][4]. It is well known that all nonlinear-optical crystals are piezoelectrics.…”

Self-Action of Second Harmonic Generation and Longitudinal Temperature Gradient in Nonlinear-Optical Crystals

“…Moreover piezoelectric laser calorimetry was successfully applied for determination of optical absorption coefficients of crystals in wide spectral range [6,7]. We developed mathematical model that proves validity of equivalent temperature concept, which suggests direct temperature measurement of nonuniformly heated crystal using its temperature calibrated piezoelectric resonances [8]. Temperature calibration of resonance frequencies is performed…”

“…We developed mathematical model that proves validity of equivalent temperature concept, which suggests direct temperature measurement of nonuniformly heated crystal using its temperature calibrated piezoelectric resonances [8]. Temperature calibration of resonance frequencies is performed in uniform equilibrium heating conditions of the crystal.…”