Lasing threshold reduction in grating-tuned cavities

Abstract

A new geometry for grating-tuned cavities that reduces optical losses from the gratings, lowers the lasing threshold, and enhances the laser output is described and tested. We achieved these enhancements by feeding back into the cavity light that is normally lost through grating reflections. The new geometry is tested on two grazing-incidence dye laser cavities: one that resembles a Littman -Metcalf design and demonstrates the essential principle of the new arrangement, and one that introduces modifications necessary to allow single-longitudinal-mode operation without mode hopping over a tuning range of ~15 cm-1 .