Small line width nanosecond dye laser of high spectral purity with double functional grating

Abstract

The authors report on a new compact pulsed dye laser cavity arrangement with a U-shaped resonator with an echelle grating and a prism deflecting beam expander with a magnification of 112. The double functional grating is a resonant reflector of the magnified and the non-magnified beam. With this apparatus the broadband background is suppressed leaving up to 0.8% of the small line width signal. The spectral line width of the laser radiation without an intracavity FP etalon is 0.15 cm-1. The line width with a 5 mm air-spaced FP etalon is 0.02 cm-1; and with a 15 mm FP etalon one-mode operation is possible. The passive wavelength stability is better than +or-0.2 pm for 2.5 min or better than +or-1 pm for 3 h. Wavelength tuning is possible by turning the grating and/or the FP etalon or by changing the pressure. The optical energy efficiency when using one amplifier stage is 5% for Rhodamine 6G at 580 nm.