Broadband, High-Reflectivity Dielectric Mirrors at Wafer Scale
Combining Photonic Crystal and Metasurface Architectures for Advanced Lightsails
J. Chang (TU Delft - QN/Groeblacher Lab, Kavli institute of nanoscience Delft)
W. Ji (TU Delft - ImPhys/Adam group)
Xiong Yao (Fudan University, TU Delft - QN/Groeblacher Lab, Westlake University)
Arnold J. van Run (TU Delft - QN/Kavli Nanolab Delft, Kavli institute of nanoscience Delft)
S. Groblacher (TU Delft - QN/Groeblacher Lab, Kavli institute of nanoscience Delft)
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Abstract
Highly ambitious initiatives aspire to propel a miniature spacecraft to a neighboring star within a human generation, leveraging the radiation pressure of lasers for propulsion. One major challenge for this enormous feat is to build a meter-scale, ultralow mass lightsail with broadband reflectivity. In this work, we present the design and fabrication of a lightsail composed of two distinct dielectric layers with photonic crystal/metasurface structure covering a 4” wafer. We achieved broadband reflection of >70% spanning over the full Doppler-shifted laser wavelength range during spacecraft acceleration with a low total mass in the range of a few grams when scaled up to meter size. Furthermore, we find new paths to reliably fabricate these subwavelength structures over macroscopic areas and then systematically characterize their optical performance, confirming their suitability for future lightsail applications. Our innovative device and precise nanofabrication approaches represent a significant leap toward interstellar exploration.
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