单向通光，俗称光二极管，是指只允许光波从一个入射方向上通过，从反方向入射则全部被截止，它是实现光计算、 光互联等功能中非常重要的一个基本光学元件. 但是在线性和非磁性材料中，光的可逆原理却要求光的传播途径是可逆的. 由此我们提出以下问题: 在线性和非磁性材料中，单向通光是否可以获得? 如果可以获得，其获得的途径又是什么? 单向通 光与光路可逆的关系如何? 围绕这些基本的物理问题，文章以光栅基底发生的波导模式共振为机制，设计并成功获得了多频 率点光波的单向通光效果. 并以此为例证明在线性和非磁性系统中光的非对称透射依然存在，它并没有打破光路可逆原理. 通过进一步分析得出了在这种系统中，光的单向通效果来源于光传播路径中非对称的传输通道的结论.

Unidirectional optical transmission，also named optical diode，it permits optical wave to transmit from one incident direction while prohibit it when wave incidents from the reversed direction. It is one of the most important optical elements of the optical calculation and optical connections. While in linear and non -magnetic material system，the optical wave has to obey the reciprocity principle of the optics and the propagation path must be reversible. So it raises the questions that: Whether the unidirectional transmission can be obtained in linear and non -magnetic material system? If the answer is yes，what is the obtaining way? And what is the relationship　between the reciprocity principles and the unidirectional transmission in linear and non-magnetic material system? In this paper，the unidirectional transmission effect is obtained at multiple frequencies based on the guided mode resonance occurred in the substrate of a dielectric grating inspired by grating diffraction. And taking it for an example，we prove that in linear and nonmagnetic system，asymmetric optical transmission is also available and the reversibility of light is still effective. Besides，through further analysis，it is found that in this kind of linear and on-magnetic system，the unidirectional optical transmission is attributed to the asymmetric propagation channels of the optical path.