Abstract

We investigate the effect of periodic modulation on PT-symmetry recovery, higher-order exceptional points (EPs) and dynamics for a periodically modulated PT-symmetric quadrimer waveguide system. It is analytically and numerically revealed that the periodic modulation not only can restore the broken PT symmetry, but also can manipulate the PT symmetry by tuning modulation amplitude. Furthermore, we found that multiple EPs can emerge, and as the modulation amplitude vary, these EPs can collide and merge, leading to higher-order Floquet singularities. By defining average relative light intensity distribution, we explore the dynamical characteristics nearby these EPs. It is found that we can control the light tunneling direction of optical quadrimer waveguide via periodic modulation and proper choice of gain/loss parameters.

Graphical abstract

中文翻译：

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PT对称四极波导中的浮点高阶例外点和动力学

摘要

我们研究周期性调制对PT对称性恢复，高阶例外点（EP）和周期性调制PT对称四边形波导系统动力学的影响。分析和数值分析表明，周期性调制不仅可以恢复破碎的PT对称性，而且可以通过调节调制幅度来操纵PT对称性。此外，我们发现可以出现多个EP，并且随着调制幅度的变化，这些EP可能发生碰撞和合并，从而导致更高阶的Floquet奇点。通过定义平均相对光强度分布，我们探索了这些EP附近的动力学特性。据发现，我们可以通过周期性的调制和增益/损耗参数适当选择控制光quadrimer波导的光隧道的方向。

图形概要