Radiation robustness of laser ceramics and single crystal for microchip laser remote analysis

Tamura, Koji; Nakanishi, Ryuzo; Oba, Hironori  ; Taira, Takunori*; Wakaida, Ikuo  

Laser pulse energy and pulse build-up time were measured during gamma irradiation at a dose rate of 150 Gy/h to evaluate the radiation-induced effects and robustnesson a laser remote inspection system using ceramics and single crystal microchip laser. Results showed a time-dependent decrease in pulse energy and increase in pulse build-up time during irradiation. Both effects were larger for ceramics than for single crystal due to the amount of generated optical loss. The behaviors of pulse energy and build-up time with the increase in optical loss in the gain medium were simulated using rate equation calculations. The radiation effect on build-up time was larger than that on pulse energy for both specimens. Therefore, build-up time measurement is highly sensitive and effective for the evaluation of radiation effect generated in laser medium, especially for radiation robust specimens or at low radiation dose rate.