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 developed a new category 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 μJ/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 studied in detail the nonlinear reflectivity, ΔR/R, of the SSBR as a function of wavelength. In particular, the influence of carrier scattering and recombination on its dynamics are elucidated. These results are instructive for the optimization of the design parameters of SSBR’s for mode-locking or nonlinear switching.

© 2001 IEEE