Ultrafast Characterization Of Semiconductor Gain And Absorber Devices For Mode-Locked Vecsels

We present a comprehensive characterization of semiconductor gain and absorber devices utilizing novel measurement techniques. Using a 20fs probe laser, a time resolution in the few femtosecond range is achieved in traditional pump and probe measurements performed on VECSELs and SESAMs. In-situ characterizations of VECSEL samples mode-locked in the sub-500fs regime reveal the fast and longtime recoveries of the gain present in real lasing conditions. Spectrally resolved probing gives further information about the properties of carriers in VECSEL gain media. Our results indicate that stable mode-locked operation is sustained by multiple carrier relaxation mechanisms ranging from a few femtoseconds to the pico- and nanosecond regimes.