Monolithic self-Q-switched Cr,Nd:YAG laser

We report the operation of a diode-pumped monolithic self-Q-switched Cr,Nd:YAG laser in which the codoped ions create saturable absorption for Nd3 " laser emission at 1064 nm. With a 70-/um beam diameter in the gain medium, the Q-switched pulse has a duration of 3.5 ns and a peak power of 2 kW. The output is linearly polarized with an extinction ratio of 600:1. The pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25%. A 5-mm-long KTP crystal butted against the with a peak power-conversion efficiency of 30%. Recently, chromium-doped host crystals, such as gadolinium scandium gallium garnet, forsterite, and yttrium aluminum garnet (YAG) were found to exhibit saturable absorption in the 900-1200-nm range. ` 3 The absorption has color-centerlike characteristics and is believed to be associated with the Cr4 " ions.4'5 Cr-doped forsterite has been used to realize passive Q switching and mode locking in Nd:YAG lasers.2 When YAG and gadoliniu