基于减反膜外腔反馈半导体激光器拉曼光的产生

Generation of Raman light source with an anti-reflection-coated edge-emitting laser diode in an external cavity

通过直接对减反膜外腔反馈半导体激光器进行电流调制的方法,得到了两束位相锁定且频率差在6.0—9.3GHz范围内连续可调的激光,其中6.835和9.192GHz分别对应Rb87和Cs133原子基态超精细能级之间的频率差,激光功率分别可以达到6.87mW和5.09mW.根据减反膜外腔反馈半导体激光器的特点,通过调整外腔腔长、激光器工作温度、电流以及所加射频调制信号的功率和频率,在调制频率小于等于4.0GHz时可以将载波完全压制.调制频率大于4.0GHz时,虽不能将载波完全压制,但由于外腔与调制频率共振时对调制的增强也得到了调制深度很高的激光,并对其中的物理机理作了分析.通过后续滤波等方法处理以后,该拉曼光源可以广泛应用到原子的量子操控中.

Phase locked two laser beams with a tunable and controllable frequency difference in a range of several GHz play a major role in the stimulated Raman transition,coherent population trapping,quantum states preparation and other quantum manipulation researches.We demonstrate such leaser beams with a tunable frequency difference in a range of 6.0—9.3GHz.In particular,the frequency differences of 6.835GHz and 9.192GHz corresponding to the ground state＇s hyperfine splitting in Rb87 and Cs133 respectively are realized experimentally.The power of the modulated beam is measured to be 6.87mW.With an antireflection-coated edge-emitting diode placed in an external cavity,we can suppress the carrier completely when the modulation frequency is lower than 4.0GHz by adjusting the external cavity length,the temperature,the current of the diode,and the power of the modulation.When the modulation is higher than 4.0GHz we cannot fully suppress the carrier,but we can also obtain the laser beams each with a high modulation depth due to modulation enhancement by external cavity resonance.