Abstract

We have produced 260 fsec pulses by passively modelocking a NaCl color center laser using multiple quantum well (MQW) saturable absorbers. This femtosecond source is a simple, single cavity, tunable, all-solid-state laser with ~2.3kW peak power. The experimental configuration consists of a NaCl cavity as described in [1] plus two 50mm lenses and a MQW sample. Our shortest pulses are obtained with an AR-coated, proton bombarded (to reduce the recombination time) sample containing 60 periods of 200Å InGaAs wells between 100 Å InAlAs barriers. We obtain pedestal-free 260fsec pulses with a bandwidth of ~ l.5THz (δνδτ = 0.39, which lies between the values for a secant hyperbolic and Gaussian pulse). By rotating a 1mm thick quartz birefringent plate, we can tune the wavelength for passive modelocking by ~40nm. Furthermore, we tuned the passive modelocking between 1.59 and 1.7μm using MQW’s with different well sizes. For each MQW, we find the optimal modelocking wavelength to be about 50nm below the heavy hole exciton peak.

© 1988 Optical Society of America