Electrically actuated varifocal lens based on liquid-crystal-embedded dielectric metasurfaces

Abstract

Compact varifocal lenses are essential to various imaging and vision technologies. However, existing varifocal elements typically rely on mechanically-actuated systems with limited tuning speeds and scalability. Here, an ultrathin electrically controlled varifocal lens based on a liquid crystal (LC) encapsulated semiconductor metasurface is demonstrated. Enabled by the field-dependent LC anisotropy, applying a voltage bias across the LC cell modifies the local phase response of the silicon meta-atoms, in turn modifying the focal length of the metalens. In a numerical implementation, a voltage-actuated metalens with continuous zoom and up to 20% total focal shift is demonstrated. The concept of LC-based metalens is experimentally verified through the design and fabrication of a bifocal metalens that facilitates high-contrast switching between two discrete focal lengths upon application of a 3.2 V${}_{\mathrm{pp}}$ voltage bias. Owing to their ultrathin thickness and adaptable design, LC-driven semiconductor metasurfaces open new opportunities for compact varifocal lensing in a diversity of modern imaging applications.

References in corpus (8)

• Subwavelength-thick Lenses with High Numerical Apertures and Large Efficiency Based on High Contrast Transmitarrays
• Phase-only transmissive spatial light modulator based on tunable dielectric metasurface
• Liquid Crystal Tunable Metamaterial Perfect Absorber
• Electro-optical switching by liquid-crystal controlled metasurfaces
• Electrically Driven Varifocal Silicon Metalens
• Active tuning of high-Q dielectric metasurfaces
• Tunability of wire-grid metamaterial immersed into nematic liquid crystal
• Tunable magnetic response of metamaterials

Cited by in corpus (7)

• Tunable Polarization-Multiplexed Achromatic Dielectric Metalens
• Metasurface Holographic Optical Traps for Ultracold Atoms
• Thermally-reconfigurable metalens
• Ultra-thin Tunable Optomechanical Metalens
• All-Optical tunability of metalenses infiltrated with liquid crystals
• Continuous Varifocal Metalens Based on Phase-Change Material
• Hybrid Si-GST Polarization-Insensitive Dynamically Tunable Bifocal Metalens Operating at 1.55-$\mu$m Wavelength