微环芯腔与锥形纳米光纤耦合过程的实验研究

在实验上研究了共振于铯原子跃迁线附近的微环芯腔与锥形纳米光纤的耦合特性。通过精密控制微环芯腔与锥形纳米光纤的相对位置,实现了两者的欠耦合、临界耦合和过耦合的精确控制。当微环芯腔与锥形纳米光纤间距为0.6μm时,系统达到临界耦合,透射率为0.3%±0.3%,耦合效率为99.7%±0.3%。由微环芯腔透射光谱得到微环芯腔的自由光谱区为1067±5GHz,等效腔长为223±1μm,线宽为2.9±0.1GHz,本征品质因数为(6.2±0.6)×10~4。随着微环芯腔与锥形纳米光纤间距的减小,微环芯腔的线宽逐渐增大,共振频率发生红移,频率移动为19.2±0.1GHz。该研究找到了有效控制微环芯腔与锥形纳米光纤耦合状态的方法,为下一步实现微环芯腔与原子间强耦合奠定了实验基础。同时该研究加深了人们对微环芯腔不同耦合状态的认识,为研究欠耦合和过耦合状态提供了实验基础。

Experimental Investigation on the Coupling Process between Microtoroidal Resonators and Tapered Nanofibers

The coupling properties between microtoroidal resonators and tapered nanofibers in the vicinity of cesium transition lines were studied experimentally in this paper.We could control the under-coupling,the critical coupling and the over-coupling precisely by controlling the corresponding position of the microtoroidal resonator and the tapered nanofiber.The critical coupling was achieved when the gap distance between the microtoroidal resonator and the tapered nanofiber was 0.6 μm.The minumum transmission was 0.3％±0.3％.The coupling efficiency was 99.7％±0.3％.The free spectral range of the microtoroidal resonator was 1067±5 GHz.The effective cavity length of the microtoroidal resonator was 223±1μm.The linewidth was 2.9±0.1 GHz,and the intrinsic quality factor was(6.2±0.6)×104.With the decrease of the gap distance,the linewidth gradually increased,and the resonant frequency of the microtoroidal resonator lay at a redshift of 19.2±0.1 GHz.The invesitgation not only gives a way to control the coupling of microtoroidal resonators and tapered nanofibers effectively,but also lays the experimental foundation for realizing the strong coupling between microtoroidal resonators and atoms.At the same time,this study deepens the understanding of the different coupling states of the microtoroidal resonator,and provides the experimental basis for the study of the under-coupling state and over-coupling state.