On‐Chip Electrically Driven Tunable Meta‐Lens for Dynamic Focusing and Beam Steering

Abstract

The on‐chip meta‐lenses consisting of subwavelength slot arrays with lateral gradients have shown great potential for parallel signal processing and optical computing. The dynamic tuning mechanisms which are necessary steps toward exploiting the applications of the on‐chip meta‐system have been rarely mentioned yet. Here, a free‐form functional microheater via topology design is proposed to manipulate the refractive index distribution, allowing for flexible optical wavefront shaping. For a proof‐of‐concept, wide range of dynamic focusing and beam steering are demonstrated via a tunable meta‐lens on silicon photonic platform. The continuous scanning of the focused beam is experimentally achieved with a maximum travel range of 100 µm in the longitudinal direction (≈95 nm mW−1) and 25 µm in the lateral direction (≈20 nm mW−1). The thermal‐optic tuning elements can response the electrical control within ≈41.2 µs. A waveguide array at the focal plane is used to characterize the device. The on‐chip loss of the tunable meta‐lens is measured to be <1 dB including the coupling loss from slab to single‐mode waveguide. The proposed tunable meta‐lenses are fabricated via a standard silicon photonic process and allow for arbitrarily two dimensional (2D) beam steering. It offers great versatility for on‐chip meta‐systems with a wider scope of functionalities and applications.

Advanced manufacturing of dielectric meta-devices

“…spectrum from UV to IR wavelengths, hold promise for enhancing metasurface performance. Furthermore, the emergence of multifunctional dielectric materials with tunable optical properties, including phase-change materials such as germanium antimony telluride (Ge 2 Sb 2 Te 5 or GST) [339] , vanadium dioxide (VO 2 ) [340] , and antimony trisulfide (Sb 2 S 3 ) [341] ; electro-optic materials like lithium niobate (LiNbO 3 ) [342] ; and thermo-optic materials like silicon (Si) [343] and liquid crystals [344] ; as well as electrical properties, such as ferroelectric materials like barium titanate (BaTiO 3 ) [345] and graphene [346] ; magnetic properties, such as multiferroic materials like bismuth ferrite (BiFeO 3 ) [347] ; and magneto-optic materials like yttrium iron garnet (YIG) [348] , along with intensity-modulated nonlinear materials like metallic quantum wells [349][350][351] , offers versatile options for metasurface fabrication and functionality enhancement. The combination of tunable properties in these materials has shown promising applications in dynamic, reconfigurable, and high-performance dielectric metasurfaces, including dynamic holograms [352] , tunable imaging [353][354][355] , active beam steering [356] , and chirality tuning in several recent studies [341] .…”