Broad tunability from a compact, low-threshold Cr: LiSAF laser incorporating an improved birefringent filter and multiple-cavity Gires-Tournois interferometer mirrors

We demonstrate prismless tuning of a compact femtosecond Cr:LiSAF laser. The employed technique, which uses a specially designed birefringent filter in combination with dispersion compensation from a pair of multiple-cavity Gires-Tournois interferometer mirrors, provides tuning over 20 nm. We give the results of theoretical modeling of the tuning velocity and the spectral width of the central passband. We show, both experimentally and theoretically, that a single birefringent plate can be used to control the oscillating bandwidth of the laser. The effect this has on the output-pulse duration has also been investigated.