Unlocking an optical bistability switch

L. A. Lugiato, M. Vadacchino, F. Castelli

Hamid Reza Hamedi, Mostafa Sahrai, Habib Khoshsima +1 more

We consider the behavior of optical bistability (OB) and multistability (OM) in a four-level atomic system involving a Rydberg state illuminated by a probe field as well as control and switching laser beams of larger intensity. When the switching field is absent, no OB arises because of the effect of Rydberg electromagnetically induced transparency. However, by application of the switching field, the hysteresis cycle appears to give rise to optical bistability, thanks to Rydberg electromagnetically induced absorption. It is further demonstrated that one can efficiently modify the OB threshold via suitable choices of system-controlling parameters. Interestingly, it is observed that this model can produce an optical switching between OB and OM with potential applications in logic-gate devices for optical communication.

J.A. Hermann, J.N. Elgin

Hui Wang

The characteristic of optical bistability switching of azobenzene molecules is discussed.First,we compute the coefficient of reverse saturable absorption based on the model of photoisomerization of azobenzene molecules.Second,we simulate and compute the process of bistability switching based on reverse saturable absorption.The result shows that the reverse saturable absorption based on photoisomerization of azobenzene molecules can realize full optical switches of bistability.We also discusse the Trans isomer σT,the Cis isomer σC and the thermal constant K to the optical bistability influence.

Haiqiang He, Bixuan Fan, Min Xie

Abstract We theoretically investigate the atomic optical bistability (AOB) in a three-level Λ-type atomic system confined in a unidirectional optical ring cavity. The role of the intensity or detuning of the control field on AOB is explored, and results show that absorption, dispersion, and nonlinearity can be modified significantly by the control field due to quantum coherence and interference in multilevel atomic systems. Thus, tuning the intensity or detuning of the control field can manipulate the switch-up and switch-down thresholds, as well as the area of the bistable hysteresis loop. According to the controllability of AOB, we design various schemes to realize dynamical all-optical switching between the high and low outputs of two bistable curves for a fixed cavity input. In addition, dynamical all-optical memory switching can be implemented by adding a pulse sequence for the intensity or detuning of the control field. For appropriate parameters, such as the cooperative coefficient, the extinction ratio of the switching can be improved dramatically.

Pierre Meystre, Murray Sargent