All-optical flip-flop based on vertical cavity semiconductor optical amplifiers.

We report the operation of an all-optical set-reset (SR) flip-flop based on vertical cavity semiconductor optical amplifiers (VCSOAs). This flip-flop is cascadable, has low optical switching power (~10 microW), and has the potential to be integrated on a small footprint (~100 microm(2)). The flip-flop is composed of two cross-coupled electrically pumped VCSOA inverters and uses the principles of cross-gain modulation, polarization gain anisotropy, and highly nonlinear gain characteristics to achieve flip-flop functionality. We believe that, when integrated on chip, this type of all-optical flip-flop opens new prospects for implementing all-optical fast memories and timing regeneration circuits.

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.