A new concept of photogeneration of cations: Evidence for photoejection of Ca(2+) and Li (+) from complexes with a crown-ether-linked merocyanine by picosecond spectroscopy.

Time-resolved transient absorption and gain spectra of DCM-crown and its complexes with Li(+) and Ca(2+) in acetonitrile are measured in the wavelength range 370-670 nm after subpicosecond excitation at 425 nm. The results give evidence for the fast formation of free DCM-crown from both excited complexes, with a faster rate for the Li(+) complex. A two-step mechanism is found for the initial decay (within 30 ps) of the free DCM-crown.

Generation of tunable subpicosecond pulses using low-Q dye cavities.

The design and operation characteristics of a low-Q cavity dye laser chain pumped by a single laser (seeded Q-switched Nd:YAG) for generating high-power tunable subpicosecond pulses are presented. Two low-Q short dye cavities in cascade pumped well above threshold followed by extracavity pulse shaping in a highly saturated absorber and amplifiers lead to stable generation of single 500-fs pulses, i.e., a pulse-shortening factor > 10(4) (from a smooth 6-ns pump pulse). Output pulse energies of 500 microJ (1-GW peak power) are produced from 40-mJ pump energy and used to generate high-power tunable subpicosecond pulses from 450 to 700 nm by supercontinuum generation, spectral selection, and amplification in dye amplifiers pumped by the same Nd:YAG laser. The spectral and time processes involved in these pulse-shortening methods are discussed with a rate-equation model.

Continuous-scanning system for single-mode wedge dye lasers.

The reflecting interference wedge used as a selective and tunable mirror in a single-mode laser cavity permits exactly matched tuning of the cavity-mode frequency and of the wedge line frequency by means of a single movement of the wedge. An experimental check is reported.

Single-mode dye laser with a double-action Fizeau interferometer.

The peculiar properties of the high-reflectivity Fizeau wedge used in reflection are pointed out and used to obtain single-mode operation of a Nd:YAG-pumped dye laser. It is demonstrated that the reflecting Fizeau wedge can have, as a cavity output coupler, the double action of selective-feedback mirror and an output filter, thus producing a background-free tunable narrow line.

Study of a 1-watt repetitive dye laser.

A repetitive flashtube pumped dye laser (pulse rate up to 30 Hz) is described. The untuned laser output average power with rhodamine 6G is 1 W. When tuned by a Perot-Fabry etalon, 0.36 W is obtained in a bandwidth of 3 A. Output power is given for several dyes emitting between 440 nm and 680 nm. The behavior of flashtubes and dye solutions after long use is discussed.