High-peak power, passively Q-switched, composite, all-polycrystalline ceramic Nd : YAG/Cr4+ : YAG lasers

High-peak power, passively Q-switched, composite Nd : YAG/Cr⁴⁺ : YAG lasers consisting of all-polycrystalline bonded Nd : YAG and Cr⁴⁺ : YAG ceramics are developed, and two applications of such lasers are discussed. A 1.1-at. %-doped Nd : YAG/Cr⁴⁺ : YAG ceramic laser is fabricated, which is quasi-cw pumped by a diode laser in the Hz-range, delivering laser pulses of 2.5-mJ energy and 1.9-MW peak power. By frequency doubling the laser output in a LiB₃O₅ (LBO) nonlinear crystal at room temperature, 0.36-mJ, 0.3-MW green laser pulses with 27 % conversion efficiency are produced at 532 nm. Furthermore, a highly doped (1.5-at. %) Nd : YAG/Cr⁴⁺ : YAG ceramic laser operates successfully in the range of pulse repetition rates from 50 to 500 Hz, yielding 0.8-to-1.0 mJ pulses with a peak power around 1 MW. The laser output beam is amplified in a master-oscillator — power-amplifier (MOPA) system to generate laser pulses with 11-mJ energy at a 250-Hz repetition rate.