Dai Zheng, Wang Zhuoran, Yao Jianping
Opt Lett. 2023 Jan 1;48(1):143-146. doi: 10.1364/OL.479154.
By exploring the relationship between the gain/loss and the coupling coefficient, parity-time (PT) symmetry has been well explored in the photonics and optoelectronics fields to achieve unique functions, such as sidemode suppression, non-reciprocal light propagation, and unidirectional invisibility. In general, a PT-symmetric system has an architecture with two identical coupled resonators or loops. In this Letter, we explore the possibility of implementing a PT-symmetric system having an architecture with one resonator having a loop length that is a rational number of times the length of the other resonator, to increase the sidemode suppression ratio. A theoretical analysis is performed, which is validated by a proof-of-concept experiment in which a fiber ring laser having two loops with a length ratio being a rational number of 200/3, supporting single-longitudinal-mode lasing at 1555.88 nm, is demonstrated. Thanks to the non-identical loop lengths, the sidemode suppression ratio is increased, which is 53.2 dB in the experiment.
通过探索增益/损耗与耦合系数之间的关系，奇偶时间（PT）对称性已在光子学和光电子学领域得到了充分研究，以实现诸如边模抑制、非互易光传播和单向隐身等独特功能。一般来说，一个PT对称系统具有由两个相同的耦合谐振器或环路组成的结构。在本信函中，我们探讨了实现一种PT对称系统的可能性，该系统的结构是一个谐振器的环路长度是另一个谐振器长度的有理数倍，以提高边模抑制比。进行了理论分析，并通过一个概念验证实验进行了验证，该实验展示了一个光纤环形激光器，其具有两个长度比为200/3（有理数）的环路，在1555.88 nm处支持单纵模激光振荡。由于环路长度不同，边模抑制比得以提高，在实验中达到了53.2 dB。
