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.