Analysis and design of widely tunable diode-pumped Cr:LiSAF lasers with external grating feedback

We report theoretical and experimental studies on the tuning characteristics of a diode-pumped single-longitudinal-mode Cr:LiSrAlF/sub 6/ laser with external optical feedback from a diffraction grating. The results of theoretical analysis explained the mechanism of wavelength tuning and agreed well with the measured characteristics. The simple relation, which describes the dependence of the threshold power on the reflectivity of the output coupler and on the feedback from the grating, was derived taking account of the wavelength dependence of the Cr:LiSrAlF/sub 6/ emission cross section. From these results we could optimize the reflectivity of the coupler for achieving broad-band tuning. It was found that the tuning range of 200 nm is possible if the feedback ratio from the grating is increased to 35%.