Abstract

We have developed a powerful, femtosecond pulse amplification chain to study high-intensity laser-matter interactions. The linear-cavity oscillator (Quantronics 4500) is synchronously pumped by a frequency-doubled Nd:YAG laser (Quantronics 416). An R6G jet acts as the gain medium, and a saturable absorber jet mode-locks the pulses. The group-velocity dispersion is compensated for by a series of four quartz prisms, with a slit between the two central prisms that permits selection of the lasing wavelength. Thus, the main characteristic of this laser is that pulses can be tuned over a range of 565-620 nm with a pulse duration between ~1 ps and ~100 fs. The amplifiers are a series of four Bethune cells transversely pumped by a frequency-doubled Q-switched Nd: YAG laser (Lumonics YP1200). The amplified spontaneous emission is filtered by a series of pinholes and saturable-absorber jets to preferentially amplify the femtosecond pulses and to improve the contrast ratio and beam quality. At 575 nm the net amplification factor is 10⁷, and 2 mJ subpicosecond pulses are produced at a repetition rate of 10 Hz, providing an intensity of 10¹⁷ W/cm² per pulse at best focus.

© 1990 Optical Society of America