Abstract

Lately, there have been substantial interests in passively mode-locked solid-state lasers with semiconductor saturable absorber mirror (SESAM) [1-3]. Pulses as short as 6.5 fs was generated. We have also developed a type of SESAM’s employing multiple-strained-quantum-wells, or Strained Saturable Absorber Mirrors, SSBR for short [4]. The SSBR exhibits saturable fluence, F_sat as low as ~ 10 pJ/cm². Widely tunable, self-starting, passively mode- locked Ti:sapphire lasers capable of sustaining stable sub-100fs pulses were generated in a cavity with the SSBR and negligible Kerr-lens-mode-locking (KLM) strength [4]. Self-starting mode-locking with record-high average power were also achieved with the SBBR [5], and employed successfully for intra-cavity THz generation [6]. Low F_sat also suggests potential applications of this device for applications such as all-optical switching and modulation. We have also studied in detail the saturation fluences and the nonlinear reflectivity, AR/R, of the SSBR as a function of wavelength. [7,8]. In this paper, we report measurements of the amplitudes and phases of pulses of various chirps reflected from the SSBR at several pumping wavelengths using the frequency-resolved optical gating (FROG) technique [9]. These results are instructive for the optimization of the design parameters of SSBR’s for modelocking or nonlinear switching.

© 2002 Optical Society of America