High-energy picosecond pulses: design of a dye-laser-amplifier system.

A synchronously pumped dye laser is constructed that uses an actively mode-locked Q-switched Nd:YAG laser as the pump source. The system consists of a grating-tuned dye oscillator and two transversely pumped and one longitudinally pumped amplifier stages. Output energies of 1.5 mJ in a 20-psec pulse at 5700 A, corresponding to a peak power of 10(8) W, are obtained by using rhodamine 6G. The energy can be increased to 3 mJ at 25 psec FWHM. Characteristics of the amplification process employing short (50-psec) pump pulses are discussed.

Amplification of ultrashort pulses in krypton fluoride at 248 nm.

Ultrashort pulses were produced at 248 nm by using a transverse-discharge KrF* excimer laser as a high-energy amplifier system. Input pulses for the amplifier system were obtained by upconverting the output of a modelocked visible dye laser to the ultraviolet by using nonlinear crystals. Pulses of up to 20 mJ; in energy with 10-30-psec duration were obtained at 10 pulses/sec. The output pulse width was characterized by using an electronic autocorrelator.

Multiphoton excitation and subsequent ionization detection of metastable atoms: measurement of n3S-n3D splittings in He.

A simple technique is described for the efficient detection of multiphoton transitions from metastable states of atomic or molecular species to their excited states of either even or odd parity. This technique is demonstrated in metastable He, and first measurements of n3S-n3D splittings for n = 18-22 are reported.