Experimental demonstration of corrugated nanolaminate films as reflective light sails.

Abstract

Achieving laser-driven relativistic light sails would represent a tremendous breakthrough for humankind. Numerous sail designs have been proposed, but none satisfy all the stringent optical, mechanical, and mass constraints. Here we demonstrate a class of nanolaminate sails with strong and flexible hexagonally-corrugated microstructures. Our prototypes, fabricated from alumina and molybdenum disulfide using scalable semiconductor processing techniques, feature areal densities of  < 1 g ⋅ m^-2, achieve experimentally-measured broadband reflectivities of  > 50%, and feature broadband absorptivities of  < 4% with a measurement uncertainty that overlaps with zero - indicative of our sail class's potential for fast acceleration and ultra-low photon absorption. Moreover, we propose a sail's maximum achievable relative velocity as a performance benchmark, and analyze optical, mechanical, and mass constraints for our design and others in the literature to highlight the strong potential of our class of sails. Our approach represents a promising step toward plausible relativistic interstellar propulsion.