Generation and modulation of high efficiency stationary optical signals in cold 87Rb atomic samples

In order to improve the performance of optical information processing components and to achieve high efficiency optical signals for static storage, a four-level double-Lambda cold 87Rb atomic system driven by two counter-propagating travelling wave fields is established, and the necessary Stationary Pulse Light(SLP) conditions of controlling coupling fields and phase modulation ways to control probe intensity are studied. First, the four-level double-Lambda cold 87Rb atomic energy level driven by two counter-propagating travelling wave fields is selected, and the forward resonance coupling field is switched on to guide only one forward incident signal into samples for detection. Then, the optical signals are stored and efficient SLPs are generated through switching on and turning off two coupling fields. The necessary conditions to generate efficient SLPs are obtained according to selecting different fine structures of energy level. Finally, the phase modulation method of control stationary light intensity is attained. The results indicate that the system can generate efficient SLPs with continue time nearly 80 μs and the phase modulation can adjust the stationary light intensity periodically. Obtained SLPs satisfy the optical signal processing requirements for higher efficiency, higher fidelity, all-optical control and long timeliness.