A new category of semiconductor nonlinear mirrors for ultrafast pulse generation and switching

We have demonstrated a new category of semiconductor nonlinear mirrors for ultrashort pulse generation. The saturation fluence of the strained saturable absorber mirror (SSBR) is as low as 10 pJ/cm/sup 2/ with normalized nonlinear reflectivity as large as 4% on resonance. The SSBR is thus also potentially useful as a nonlinear switching device. The carrier dynamics of the SSBR has been investigated in detail. We show that the wavelength-dependence of the fast and slow components of the carrier lifetime is significant for the performance of the SSBR as an effective saturable absorber for stable mode-locking.