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

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 mu m in the longitudinal direction (approximate to 95 nm mW(-1)) and 25 mu m in the lateral direction (approximate to 20 nm mW(-1)). The thermal-optic tuning elements can response the electrical control within approximate to 41.2 mu s. 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.

Automated summary

This study proposes a free-form functional microheater with topology design to manipulate the refractive index distribution, enabling flexible optical wavefront shaping. Wide range of dynamic focusing and beam steering are demonstrated with a tunable meta-lens on a silicon photonic platform. The proposed tunable meta-lenses have fast thermal-optic response time and low on-chip loss, offering versatility for various on-chip meta-systems.