Intensity dependent polarization in a semiconductor multiple quantum-well amplifier

It is shown numerically that the polarization evolution in a semiconductor multiple-quantum-well amplifier is intensity dependent for an input light partially coupled in both polarization modes because of the anisotropy of gain saturation. This phenomenon can be used for nonlinear polarization switching. By placing a polarization beam splitter at the output end, self-polarization switching is obtained. In the case of pulsed inputs, time-dependent polarization is observed, leading to pulse breakup and a poorer switching contrast in nonlinear switching. When the width of the input pulse is much larger than the carrier lifetime, the time-dependent polarization distribution is symmetric, and a strong single hump as well as weak two-hump pulses are observed at the two output ports, respectively.<
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