Beam steering at the nanosecond time scale with an atomically thin reflector

TL;DR

This paper demonstrates a nanosecond-scale, electrically tunable beam steering device using an atomically thin semiconductor and graphene, enabling rapid, programmable control of light with potential for advanced optical systems.

Contribution

It introduces a novel, fast, and tunable beam steering mechanism based on atomically thin materials and electrostatic gating, achieving nanosecond switching times.

Findings

Achieved 10° beam deflection range.

Demonstrated 1.6 nanoseconds switching time.

Enabled two-dimensional beam steering.

Abstract

Techniques to mold the flow of light on subwavelength scales enable fundamentally new optical systems and device applications. The realization of programmable, active optical systems with fast, tunable components is among the outstanding challenges in the field. Here, we experimentally demonstrate a few-pixel beam steering device based on electrostatic gate control of excitons in an atomically thin semiconductor with strong light-matter interactions. By combining the high reflectivity of a MoSe2 monolayer with a graphene split-gate geometry, we shape the wavefront phase profile to achieve continuously tunable beam deflection with a range of 10$^\circ$, two-dimensional beam steering, and switching times down to 1.6 nanoseconds. Our approach opens the door for a new class of atomically thin optical systems, such as rapidly switchable beam arrays and quantum metasurfaces operating at their fundamental thickness limit.