Investigation of Tunable Structured Light Using Bilayer Parity-Time Symmetry Dammann Grating Metasurfaces

TL;DR

This paper presents a novel, dynamically tunable double-layer Dammann grating metasurface using PT symmetry and rotational transformations to control structured light properties, enabling adaptable optical components.

Contribution

It introduces a new design of a double-layer DG metasurface with PT symmetry and Moiré effect for dynamic tunability in structured light applications.

Findings

Significant variations in diffraction spot shape, position, and intensity with different PT states and rotations.

Enhanced control over conversion efficiency and contrast ratio through structural modifications.

Demonstrated potential for flexible, tunable structured light devices.

Abstract

In the current technological landscape, structured light technology holds a critically important position. However, traditional structured light optical components often require complex systems and extensive resources for application, and they function in a fixed manner. This study takes this challenge as an opportunity to design a novel dynamically tunable double-layer Dammann grating (DG) metasurface. During the research, we developed a double-layer DG metasurface structure using silica as the substrate and lithium niobate (LiNbO3, LN) as the nanocolumn material. By specifically introducing parity-time (PT) symmetry, we designed three distinct states, combined with rotational transformations leveraging the Moir\'e effect. Further investigations revealed that for metasurfaces with different radius combinations, changes in rotation and PT symmetry states resulted in significant variations in the shape, position, and intensity of the diffraction spots, alongside changes in conversion efficiency and contrast ratio. This study thoroughly and comprehensively unveils the significant impacts of rotational transformations, PT symmetry, and radius combination on the optical characteristics of double-layer DG metasurfaces, providing a new method for the design of dynamic tunable optical components with structured light.