Analysis of Quantum Dot Vertical Cavity Semiconductor Optical Amplifier with Saturable Absorber

We analyze the bistable characteristics of quantum dot vertical cavity semiconductor optical amplifier integrated with saturable absorber. The device demonstrates bistable characteristics in the input-output powers which can be controlled by changing the voltage of the saturable absorber. We observe that the lower trigger level is more sensitive to variation of the absorption coefficient of the saturable absorber than that of upper trigger level. For clockwise and butterfly loops, we find that the upper and lower trigger levels increase as the absorption coefficient increases, and consequently the hysteresis width decreases. For counter clockwise, the upper and lower trigger levels decrease as the absorption coefficient increases and the corresponding hysteresis width increases.