Observation of wavelength and multiple bistabilities in 850nm Vertical-Cavity Semiconductor Optical Amplifiers (VCSOAs).

Both wavelength bistability (WB) and multiple bistability (MB) were predicted theoretically by Adams' model in resonant optical amplifiers. We report here, for the first time to our knowledge, their experimental observation in 850nm Vertical-Cavity Semiconductor Optical Amplifiers (VCSOA). Clockwise hysteresis of WB is observed at constant input power while the input wavelength is swept across the gain window. MB is observed at a fixed operation wavelength biased on the long-wavelength side of the two separated Polarization-Dependent Gain (PDG) windows of the VCSOA by sweeping the optical input. The polarization of the input is set to a fixed angle with respect to the two intrinsic principal axes of the VCSOA. Two MB levels were experimentally observed at 160muW and 320muW, respectively. These observations are in good agreement with theoretical prediction by Adams' model and may lead to multi-valued optical information manipulation.