Passively Q-switched Nd:YAG microchip lasers and applications

Passively e-switched Nd:YAG microchip lasers are robust, compact, economical, all-solid-state sources of coherent, subnanosecond, multikilowatt pulses at high repetition rates. When pumped with the cw output of commercially available infrared diode lasers, these diminutive, quasi-monolithic devices produce 1.064-mu m pulses with a pulse width as short as 218 ps, pulse energy up to 250 mu J, and peak power up to 565 kW, without any switching electronics. The high output intensities of the microchip lasers enable the construction of extremely compact nonlinear optical systems capable of operating at any wavelength from 5000 to 190 nm. The short pulses are useful for high-precision ranging and 3-dimensional imaging using time-of-flight techniques. When focused, the output intensities are sufficient to photoablate materials, with applications in laser-induced breakdown spectroscopy and micromachining. The ultraviolet harmonics of the microchip laser have been used to perform fluorescence spectroscopy for a variety of applications, including environmental monitoring. Systems based on passively e-switched microchip lasers, like the lasers themselves, are small, efficient, robust, and potentially low cost, making them ideally suited for field use. (C) 2000 Elsevier Science S.A. All rights reserved.