A 10 kHz, broadly tunable (305-334 nm) Ce3+:LiLuF4 laser is found to flip polarization when tuning about the long wavelength peak at 327 nm. We now present investigations into this behavior which show that at 327 nm the σ-polarized small signal gain is higher than π polarized small signal gain thus accounting for the polarization flipping. However it was also found that when the laser cavity forced σ-polarized laser oscillation the laser output was smaller than that obtained when π-polarized laser oscillation was forced, indicating the presence of a polarization specific loss. Absorption studies of Ce:LiLuF suggest that there is a large ESA cross-section for σ-polarization. The presence of this polarization-specific ESA would account for the reduction in power extraction efficiency for σ-polarized lasing resulting in the relatively low output powers obtained when the laser flips to σ-polarization.
© 2001 Optical Society of AmericaPDF Article