Ultrathin spatial light modulator based on liquid crystal-based metasurface

Abstract

The invention discloses an ultrathin spatial light modulator based on a liquid crystal-based metasurface. The ultrathin spatial light modulator is mainly composed of a resonance type Huygens metasurface, an upper substrate, a birefringence medium environment, an upper electrode layer and a lower electrode layer. The micro-nano modulation unit of the metasurface is immersed into a liquid crystal medium environment of which electromagnetic parameters can be adjusted by external stimulation, so that the resonant spectrum position can be dynamically changed, and pure phase modulation in a 2pi range can be realized for incident light with a certain fixed working wavelength. Compared with the traditional liquid crystal spatial light modulator, the change of the light wave phase mainly occurs in the metasurface structure with the sub-wavelength thickness and does not depend on the phase accumulation of the metasurface structure when the metasurface structure is propagated in the liquid crystal, so that the longitudinal size of the device can be greatly reduced, an ultra-thin and ultra-high-resolution active optical device is really realized, and the application prospect is wide. The design freedom degree is high, machining is easy, and the good development prospect is achieved in the fields of laser radars, adaptive optics and the like.

Description

technical field [0001] The invention relates to the field of micro-nano optics technology, in particular to an ultra-thin spatial light modulator based on a liquid crystal-based metasurface. Background technique [0002] The traditional light wave phase modulation scheme mainly relies on the phase accumulation when the beam propagates in the medium, so a very high thickness of the medium layer is usually required to achieve the required phase dynamic range. In addition, due to the limitation of device thickness, the pixel size of such optical devices is also difficult to make small. Inevitably, there are shortcomings such as small diffraction angle of the outgoing beam and small field of view. The metasurface, as a two-dimensional artificial periodic structure material, has sub-wavelength level thickness and unit size, which can make the phase, amplitude, polarization state and other parameters of light waves change suddenly. Compared with traditional optical devices, meta...

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Problems solved by technology

However, the existing liquid crystal-based metasurfaces based on Mie resonances usually cannot cover the 2π phase modulation range due to the low quality factor of such resonances, and the application scenarios are limited.

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