Dynamic One-Dimensional Beam Shaping via a Mechanically Tunable Bilayer Metasurface

Tunable metasurfaces have emerged as a promising platform for active wavefront control beyond the static functionality of conventional designs. Although mechanical actuation in bilayer metasurfaces offers large tuning ranges and robust operation, previous studies have predominantly focused on two-dimensional (2D) beam control that requires complex phase profiles and is subject to design constraints arising from the limited degrees of freedom available in two-axis modulation. In contrast, one-dimensional (1D) optical beams-widely used in line-scan imaging and light-sheet microscopy-remain largely unexplored for mechanical tuning, despite their potential for simpler implementation. In this work, we propose a simple yet effective design principle for a bilayer metasurface capable of actively tuning various 1D optical beams. The approach exploits the additional design freedom along the axis orthogonal to the phase profiles used for 1D beam shaping, enabling controllable beam modulation with minimal structural complexity. We validate the feasibility of the proposed principle through theoretical analysis and experimental demonstration at a near-infrared wavelength.