Photonic Unit Cell Research Articles

Active Metasurfaces for Non‐Rigid Light Sail Interstellar Optical Communication

AbstractThe non‐rigidity of the nanophotonic metasail platform and the intense imparted optical force from the terrestrial laser source lead to deformations during the propulsion stage. These deformations must be taken into consideration due to their potential adverse impact on communication performance. Alterations in the shape of the sail body result in varying angles of incidence and polarization components observed by the photonic unit cell, significantly impacting their intended performance. Based on this premise, this paper proposes utilizing a reflective all‐dielectric, low‐power active metasurface that dynamically compensates for the effects of deformation and facilitates beam‐steering for communication purposes among different light sails in interstellar space. Configured as p‐n multi‐junction layers, the constituent elements of the metasurface enable modulation of carrier concentrations through multigate biasing. Through electrostatic simulations, it demonstrates that the required permittivity modulation of can achieve a wide phase span of 320°. Furthermore, it has investigated the effect of the presence of non‐functional portions in the far‐field radiation pattern of the light sail and highlighted the critical role of tunable elements in mitigating its impact. The obtained results hold great promise for realizing successful interstellar downlink communication between such gram‐scale nano‐crafts and Earth.