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 803-831nm (28nm), 828-873nm (45nm) and 890-923nm (33nm) were demonstrated using three different saturable Bragg reflectors with reflectivity bands centered at around 800, 850, and 910nm, respectively. With Cr:LiCAF gain medium, a femtosecond tuning range of 767-817nm (50nm) was demonstrated using the 800nm 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 Al 0.95Ga0.05As/Al0.17Ga0.83-based saturable Bragg reflectors for use in Cr:colquiriites.