Omnidirectional nonreciprocal absorber realized by the magneto-optical hypercrystal

TL;DR

This paper introduces a novel magneto-optical hypercrystal design that achieves omnidirectional nonreciprocal light absorption over a wide angle, advancing optical device performance with high efficiency.

Contribution

It presents the first design of nonreciprocal, wide-angle photonic bandgaps using magneto-optical hypercrystals in one-dimensional photonic structures.

Findings

Achieved high absorption (~0.99) for forward incident light at wide angles (20-75 degrees).

Demonstrated low absorption (~0.25) for backward incident light, enabling nonreciprocal behavior.

Designed a dispersionless cavity mode for forward and backward light, facilitating unidirectional optical devices.

Abstract

Photonic bandgap design is one of the most basic ways to effectively control the interaction between light and matter. However, the traditional photonic bandgap is always dispersive (blueshift with the increase of the incident angle), which is disadvantageous to the construction of wide-angle optical devices. Hypercrystal, that the photonic crystal with layered hyperbolic metamaterials (HMMs), can strongly modify the bandgap properties based on the anomalous wavevector dispersion of the HMM. Here, based on phase variation compensation between HMM and isotropic dielectric layers, we propose for the first time to design nonreciprocal and flexible photonic bandgaps using magneto-optical HMMs in one-dimensional photonic crystals. Especially for the forward and backward incident light, the blueshift and dispersionless of the forward and backward cavity modes are designed respectively to realize the interesting omnidirectional nonreciprocal absorber. Our results show high (low) absorption about 0.99 (0.25) in an angle range of 20-75 degrees for the forward (backward) incident light at the wavelength of 367 nm. The nonreciprocal omnidirectional cavity mode not only facilitates the design of perfect unidirectional optical absorbers working in a wide-angle range, but also possesses significant applications for all-angle reflectors and filters.