Spectroscopic and laser oscillation characteristics of highly Cr/sup 4+/-doped forsterite

We investigated the absorption, fluorescence and lasing characteristics of chromium-doped forsterite with high Cr/sup 4+/-ion concentration. This crystal has a large absorption coefficient of 3.2 cm/sup -1/ at the fundamental wavelength (1064 nm) of Nd: YAG laser which is used as the pump laser. Using this crystal of which size was only 5/spl times/5/spl times/5 mm/sup 3/, laser oscillation was achieved by pumping with 1064-nm pulses from a Q-switched Nd:YAG laser. The output energy of over 1.2 mJ and 25% slope efficiency, which is the highest value achieved in the case of pulse operation to our knowledge, were obtained. In this case, 70% of the pump energy was absorbed in the crystal during the first pass through at the maximum output energy.