Abstract

We have hybridly mode-locked a Styryl 9 dye laser using a nonlinear mirror that consists of a 200-nm bulk GaAlAs (5% Al content) layer grown on a linear Bragg mirror. The dye laser is synchronously pumped by compressed and frequency doubled Nd:YAG laser pulses (3.5-psec pulses, 200-mW average power). With regular mirrors the pulses have durations of 900 fsec and extended wings lead to a time-bandwidth product p = 0.64. The replacement of one mirror by a nonlinear mirror leads to a significant mode-locking improvement and pulse shortening without the need for an external cavity. Best performance of the laser is obtained near the band-edge of the GaAlAs material. At 836 nm, practically bandwidth-limited 220 fsec pulses (p = 0.44) are generated with an average output power of 15 mW. To our knowledge this is the first time that a bulk GaAlAs semiconductor instead of a multiple quantum well structure has been used for modelocking. The bulk GaAlAs material has a high saturation energy and requires no additional treatment for the reduction of the carrier recombination time. It simply acts as a slow saturable absorber.

© 1991 Optical Society of America