We theoretically investigate the optical second-order sideband generation (OSSG) in an optical parity-time (PT) symmetric system, which consists of a passive cavity trapping the atomic ensemble and an active cavity. Compared with the double-passive system, it is found that near the exceptional point (EP), the efficiency of the OSSG increases sharply not only for the blue probepump detuning resonant case but also for the red one. Using experimentally achievable parameters, we study the effect of the atomic ensemble on the efficiency of the OSSG in the PT-symmetric system. The numerical results show that the efficiency of the OSSG is 30% higher than that of the first-order sideband, which is realized easily by simultaneously modulating the atom-cavity coupling strength and detuning. Moreover, the efficiency of the OSSG can also be tuned effectively by the pump power, and the efficiency is robust when the pump power is strong enough. This study may have some guidance for modulating the nonlinear optical properties and controlling light propagation, which may stimulate further applications in optical communications.

中文翻译：

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奇偶时间对称光机电系统中的可调光学二阶边带效应

我们在理论上研究了光学奇偶时间（PT）对称系统中的光学二阶边带生成（OSSG），该系统由捕获原子团的无源腔和有源腔组成。与双无源系统相比，发现在异常点（EP）附近，不仅对于蓝色探极泵失谐共振情况，而且对于红色探极泵失谐情况，OSSG的效率都急剧提高。使用实验可达到的参数，我们研究了原子整体对PT对称系统中OSSG效率的影响。数值结果表明，OSSG的效率比一阶边带高30％，这是通过同时调制原子-空穴耦合强度和失谐来轻松实现的。此外，OSSG的效率还可以通过泵浦功率进行有效调整，并且当泵浦功率足够强大时，效率也很稳定。这项研究可能对调制非线性光学特性和控制光传播有一些指导，这可能会刺激光通信的进一步应用。