A dual-band asymmetric transmission (AT) device with high contrast ratio based on bilateral compound metallic gratings is proposed. The AT structure can be manufactured through connecting silver gratings on the outer surface and inner inverted T-shaped grating with an Ag film. Dual-band forward transmission arises from unidirectional surface plasmon polaritons (SPPs) excitation by the upper metallic grating when the modulated forward wave vector matches the wave vector of SPPs. The device can achieve a high transmittance of 0.67 and 0.82 with a contrast ratio of 0.997 and 0.99 at operation wavelengths 627 nm and 1238 nm, respectively. Since the SPPs coupling between two metallic structures can be used to suppress the forward transmission in specific frequency band, single-band AT function also can be realized. By adjusting those underlying parameters, the designed structure having AT capability at 624 nm and band-pass filter function at 1234 nm. The proposed structure is simple and feasible, and has great potential applications in the field of integrated optoelectronics.

提出了一种基于双边复合金属光栅的高对比度双波段非对称传输（AT）装置。可以通过将外表面的银光栅和内部倒T形光栅与Ag膜连接来制造AT结构。当已调制的正向波矢量与SPP的波矢量匹配时，上金属光栅会激发单向表面等离子体激元（SPPs），从而产生双波段正向传输。该器件在工作波长627 nm和1238 nm处的对比度分别为0.997和0.99时，可以实现0.67和0.82的高透射率。由于可以使用两个金属结构之间的SPP耦合来抑制特定频带中的前向传输，因此也可以实现单频带AT功能。通过调整这些基本参数，所设计的结构在624 nm处具有AT功能，并在1234 nm处具有带通滤波器功能。所提出的结构简单可行，在集成光电领域具有巨大的潜在应用前景。