All-optical switch for constructing input-output-independent logic gate in atomic systems

We propose an input-output independent logic gate via optical switching effect in a four-level tripod atomic model. The properties of the switch are investigated from the intensity, line shape and detuning of the probe field and the switching field, respectively. Different from the previous researches on all-optical switch, there are two switching fields as inputs and one probe field as output in this model. This enables an "or" logic gate in which the input and output can be controlled independently. Thus we can control the output “on” and “off” through two switching fields and freely adjust the strength of the output without changing the switching field. By adjusting the coherence conditions, the ideal optical switching phenomenon such as higher switching efficiency and larger switching speed is realized, which provides new idea to design optical communication or optical gain devices.