Femtosecond tuning of Cr:colquiriite lasers with AlGaAs-based saturable Bragg reflectors

Abstract

We present a detailed experimental study of femtosecond tuning with Cr:LiSAF and Cr:LiCAF gain media using Al0.95Ga0.05As/Al0.17Ga0.83As-based saturable Bragg reflectors. In the experiments with Cr:LiSAF gain media, femtosecond tuning ranges of 803–831 nm (28 nm), 828–873 nm (45 nm) and 890–923 nm (33 nm) were demonstrated using three different saturable Bragg reflectors with reflectivity bands centered at around 800, 850, and 910 nm, respectively. With Cr:LiCAF gain medium, a femtosecond tuning range of 767–817 nm (50 nm) was demonstrated using the 800 nm saturable Bragg reflector. Pulses as short as 26 fs with Cr:LiSAF and 39 fs with Cr:LiCAF have been obtained, which we believe are the shortest pulses reported from Cr:colquiriite laser systems mode locked with saturable Bragg reflectors. This study further illustrates the benefits and limitations of Al0.95Ga0.05As/Al0.17Ga0.83As-based saturable Bragg reflectors for use in Cr:colquiriites.