Fourier-component engineering to control light diffraction beyond subwavelength limit

TL;DR

This paper introduces a method to control light diffraction beyond the subwavelength limit by engineering Fourier harmonic components, enabling suppression of unwanted diffraction and realization of bound states in the continuum.

Contribution

It presents modified diffraction equations and a Fourier component engineering approach to surpass the traditional subwavelength diffraction limit.

Findings

Achieved suppression of unwanted diffraction orders.

Demonstrated bound states in the continuum beyond subwavelength scale.

Enhanced zero-order spectral responses with high efficiency.

Abstract

In conventional diffraction theory, a subwavelength period is considered a prerequisite to achieve interesting resonance-assisted physical phenomena, such as bound states in the continuum and diverse zero-order spectral responses with $100\%$ diffraction efficiency. Here, we present modified diffraction equations that provide mechanisms to control light diffraction beyond the subwavelength limit. We show that resonant diffraction phenomena are governed by the superposition of scattering processes, owing to higher Fourier harmonic components. By appropriately engineering the Fourier harmonic components in the grating parameters, unwanted diffraction orders can be suppressed. Moreover, bound states in the continuum and highly efficient zero-order spectral responses can be achieved beyond the subwavelength limit. The concept of engineering Fourier harmonic components in periodic modulations provides new mechanisms to overcome the diffraction limit.