Automatically tunable second-harmonic generation of dye lasers

A new technique which realizes the phase-matching of second harmonic generation (SHG) over a wide spectral range without mechanical or temperature tuning of the SHG crystal is developed. The phase-matching is achieved by changing the angle of the laser beam incident on the SHG crystal using dispersive components such as gratings or prisms. Over the entire spectral range of a Rhodamine-6G dye laser, the phase-matching is realized with a KDP crystal using this technique. This system is capable of producing tunable coherent ultraviolet light from 2300 Å to 3500 Å with an extremely fast scanning rate, if the dispersion of the prism and the SHG crystal is carefully matched.