Nonlinear absorption of Cr<SUP>4+</SUP>:YAG studied with lasers of different pulsewidths

초록

A saturable absorber Cr4+:YAG, used for a passive Q switching of Nd: YAG laser was studied in order to understand the physical mechanism of nonlinear absorption (photobleaching). An optical bleaching experiment was carried out using the two pulsed lasers with duration of pico- and nanoseconds at 1.064 mu m wavelength. Experimental results were compared with numerical analysis of theoretical rate equations with all relevant energy levels. The inclusion of intersystem crossing between singlet- and triplet- excited states with reasonable rate of transition k(isc) was necessary to explain the difference in the saturation behaviors for nanosecond and picosecond laser pulses. (C) 1998 American Institute of Physics. [S0003-6951(98)02448-6].

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