Narrow-frequency sharp-angular filters using all-dielectric cascaded meta-gratings

• Main Authors: Liu Wei-Nan, Chen Rui, Shi Wei-Yi, Zeng Ke-Bo, Zhao Fu-Li, Dong Jian-Wen
• Format: Article
• Language: English
• Published: De Gruyter 2020-06-01
• Series: Nanophotonics
• Subjects: cascaded meta-gratings; fabry-perot; spectral and angular selectivity; subwavelength grating
• Online Access: https://doi.org/10.1515/nanoph-2020-0141

Selective transmission or filtering always responds to either frequency or incident angle, so as hardly to maximize signal-to-noise ratio in communication, detection and sensing. Here, we propose compact meta-filters of narrow-frequency sharp-angular transmission peak along with broad omnidirectional reflection sidebands, in all-dielectric cascaded subwavelength meta-gratings. The inherent collective resonance of waveguide-array modes and thin film approximation of meta-grating are employed as the design strategy. A unity transmission peak, locating at the incident angle of 44.4° and the center wavelength of 1550 nm, is demonstrated in a silicon meta-filter consisting of two-layer silicon rectangular meta-grating. These findings provide possibilities in cascaded meta-gratings spectroscopic design and alternative utilities for high signal-to-noise ratio applications in focus-free spatial filtering and anti-noise systems in telecommunications.