WIDELY TUNABLE OPERATION OF TI-SAPPHIRE LASERS UNDER OPTIMUM COUPLING CONDITION

Widely tunable operation of Ti:sapphire lasers under the optimum coupling condition was investigated. The rate equation analysis on the pulsed Ti:sapphire laser shows that the tunable range can be extended by increasing the cavity-Q value and the pump laser fluence, and this was demonstrated with a Nd:YAG laser-pumped Ti:sapphire laser. If a coupling mirror has a wavelength-dependent reflectivity which increases in shorter and longer wavelengths of the tunable region, the entire spectral region can be tuned under the optimum coupling condition. A dielectric-coated coupling mirror with such wavelength dependence was developed, and a pulsed Ti:sapphire laser was operated under the nearly optimum condition over its tunable range of 690-960 nm without exchanging the mirror. The conversion efficiency was 30% at the maximum point.