Optical nonlinearity and ultrafast-carrier dynamics of a strained quantum-well saturable Bragg reflector

Abstract

We present observations of the wavelength-dependent time-resolved differential reflection in the multiple-strained-quantum-well saturable Bragg reflector (SSBR). It is shown that the large optical nonlinearity of transient reflectivity (DeltaR/R) of similar to4% for a pumping wavelength of 755 nm sharply reversed to -0.6% at 760 nm. The relationships of fast- and slow-carrier lifetimes with pumping wavelength are also discussed. We conclude that the strain-induced piezoelectric field and free-electron absorption play a dominant role in determining the optical nonlinearity and its carrier dynamics. This is the first time that wavelength-dependent time-resolved reflectivity in SSBR has been presented in detail.