In this paper, we have studied two different mechanisms of nonreciprocal and asymmetric transmission in the one-dimensional asymmetric optical system composed of parity-time (PT) and magneto-optical materials with different defect layers. It is shown that there are three pairs of nonreciprocal dispersive curves with the perfect transmission in the three different band gaps, when the defect layer is filled with normal material. When the defect layer is filled with magneto-optical material, the transmittivity of two nonreciprocal frequencies can be modulated by the magnitude and direction of the defect layer’s external magnetic field and appears to be asymmetric nonreciprocal transmission. One-way frequency corresponding to one direction has extraordinary transmission, and the other one-way frequency corresponding to the opposite direction is suppressed. When the defect layer is filled with loss or gain material, the transmittivity of two nonreciprocal frequencies can be amplificated or attenuated simultaneously, respectively. The nonreciprocal propagation is originated from the resonant modes in the system due to the defect layer, and the nonreciprocal and asymmetric transmission is determined by the broken PT system due to magneto-optical and gain/loss material in the defect layer. Such controllable and asymmetric nonreciprocal propagation in the composite system may have broad potential applications in nonreciprocal communication and integration devices.

中文翻译：

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具有两类缺陷的奇偶时间对称系统中的非互易传输

在本文中，我们研究了由奇偶时间（PT）和具有不同缺陷层的磁光材料组成的一维非对称光学系统中的两种互不对称和非对称传输的机制。结果表明，当缺陷层填充正常材料时，在三种不同的带隙中存在三对具有完美透射的非互易色散曲线。当缺陷层填充磁光材料时，两个非互易频率的透射率可以通过缺陷层外部磁场的大小和方向进行调制，表现为非对称非互易透射。一个方向对应的单向频率具有非凡的传输，并且相反方向对应的另一个单向频率被抑制。当缺陷层填充有损耗或增益材料时，两个非互易频率的透射率可以分别同时放大或衰减。非互易传播源于系统中由于缺陷层的谐振模式，非互易和不对称传输是由缺陷层中的磁光和增益/损耗材料导致的破坏 PT 系统决定的。这种在复合系统中的可控非对称非互易传播可能在非互易通信和集成设备中具有广泛的潜在应用。两个非互易频率的透射率可以分别同时放大或衰减。非互易传播源于系统中由于缺陷层的谐振模式，非互易和不对称传输是由缺陷层中的磁光和增益/损耗材料导致的破坏 PT 系统决定的。这种在复合系统中的可控非对称非互易传播可能在非互易通信和集成设备中具有广泛的潜在应用。两个非互易频率的透射率可以分别同时放大或衰减。非互易传播源于系统中由于缺陷层的谐振模式，非互易和不对称传输是由缺陷层中的磁光和增益/损耗材料导致的破坏 PT 系统决定的。这种在复合系统中的可控非对称非互易传播可能在非互易通信和集成设备中具有广泛的潜在应用。