冷铷原子样品中高效静态光信号的生成与调制

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

为了提高光信息处理元件的性能,实现高效率光信号的静止与存储,本文建立了由双向耦合场耦合的冷铷(87Rb)原子的四能级双Λ型能级机制,并对此机制在生成静态光信号时要求的高效性、持续时间,控制耦合场所需的操作条件以及对信号场强度的相位调制等进行了研究。首先,选取四能级双Λ型87Rb冷原子精细能级,用一对反向传播的行波激光场对能级进行近共振耦合,并沿耦合场方向输入一个正向弱光信号进行探测。接着,通过适当的绝热开启、关闭耦合场,存储光信号和生成高保真度静态光信号。然后,通过选取87Rb原子的不同精细能级结构,得出实现静态光所需满足的必要条件。最后,采用相位调制法对光信号进行处理。结果表明:生成的静态光信号具有高效性,过程持续时间约为80μs;相位调制法可以周期调节静态光脉冲的强度。在此机制下生成的静态光信号满足高效性、易于全光调节和长时效性等要求。

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.