Tunable metasurfaces via subwavelength phase shifters with uniform amplitude
arXiv:1610.01966 · doi:10.1038/srep40174
Abstract
Metasurfaces with tunable spatial phase functions could benefit numerous applications. Currently, most approaches to tuning rely on mechanical stretching which cannot control phase locally, or by modulating the refractive index to exploit rapid phase changes with the drawback of also modulating amplitude. Here, we propose a method to realize phase modulation at subwavelength length scales while maintaining unity amplitude. Our device is inspired by an asymmetric Fabry-Perot resonator, with pixels comprising a scattering nanopost on top of a distributed Bragg reflector, capable of providing a nearly 2π nonlinear phase shift with less than 2% refractive index modulation. Using the designed pixels, we simulate a tunable metasurface composed of an array of moderately coupled nanopost resonators, realizing axicons, vortex beam generators, and aspherical lenses with both variable focal length and in-plane scanning capability, achieving nearly diffraction-limited performance. The experimental feasibility of the proposed method is also discussed.
References in corpus (10)
- Dielectric Metasurfaces for Complete Control of Phase and Polarization with Subwavelength Spatial Resolution and High Transmission
- Aberration-free ultra-thin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces
- Subwavelength-thick Lenses with High Numerical Apertures and Large Efficiency Based on High Contrast Transmitarrays
- Multiwavelength Achromatic Metasurfaces by Dispersive Phase Compensation
- Gate-tunable conducting oxide metasurfaces
- High-Efficiency All-Dielectric Metasurfaces for Ultra-Compact Beam Manipulation in Transmission Mode
- Flat Dielectric Grating Reflectors with High Focusing Power
- Multiwavelength polarization insensitive lenses based on dielectric metasurfaces with meta-molecules
- Low Contrast Dielectric Metasurface Optics
- Efficient Dielectric Metasurface Collimating Lenses for Mid-Infrared Quantum Cascade Lasers