Frequency resolved optical gating studies of strained saturable Bragg reflector: Anomalous dispersion near resonance absorption of the exciton resonance

Abstract

A strained saturable Bragg reflector (SSBR) for passive mode-locking of Ti:sapphire lasers was investigated by the frequency resolved optical gating (FROG) technique. Incident pulses of several wavelengths and with zero, positive, or negative chirp were employed. A considerable pulse shortening near the excitonic resonance of the strained quantum well was observed and attributed to anomalous dispersion due to resonance absorption. On the long wavelength side of exciton resonance, however, the chirp of the reflected pulse showed a weak wavelength dependence attributed to the material dispersion of SSBR in pulse broadening was obtained.