Optical bistability in double quantum dot structure

This work studies optical bistability (OB) in the double quantum dot (DQD) structure. The transition momenta considered here are calculated assuming the orthogonalized plane wave for the wetting layer-quantum dot transitions. Increased tunneling increases the OB threshold and the hysteresis loop width. With increasing the transition parameter, a noticeable reduction in the OB threshold, and the hysteresis loop width is reduced. Increasing the Rabi probe frequency fewly increases the OB threshold and gives the broadest hysteresis loop. Such results are of valuable importance in applications. Optical multistability (OM) in this DQD system can be obtained under a low input field when the ground state relaxation time is longer than other states relaxation. Also, tunneling, detuning, transition parameters, and Rabi probe frequency control the OM threshold. Under higher tunneling, bistability is removed, and a linear relation is obtained. At small detuning, the OM is changed into OB. The OM behavior obtained here resembles the oppositely directed couplers. But, here, the hysteresis loops of the switching-down and the switching-up loops are not crossing. This gives additional merits to OM behavior. Low-threshold OM with enough hysteresis width is favored in all-optical switching and memory device applications.