LASING THRESHOLD REDUCTION IN GRATING-TUNED CAVITIES

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 feed ing back into the cavity light that is normally lost through grating r eflections. The new geometry is tested on two grazing-incidence dye la ser cavities: one that resembles a Littman-Metcalf design and demonstr ates the essential principle of the new arrangement, and one that intr oduces modifications necessary to allow single-longitudinal-mode opera tion without mode hopping over a tuning range of similar to 15 cm(-1). (C) 1997 Optical Society of America.