Broadband, High-Reflectivity Dielectric Mirrors at Wafer Scale: Combining Photonic Crystal and Metasurface...

Area of Science:

• Materials Science
• Aerospace Engineering
• Optics

Background:

• Interstellar travel necessitates advanced propulsion systems.
• Laser-propelled lightsails offer a potential solution for rapid transit.
• Developing large-scale, lightweight, and highly reflective lightsails is a critical challenge.

Purpose of the Study:

• To design and fabricate a meter-scale, ultralightweight lightsail with broadband reflectivity.
• To address the challenge of creating macroscopic subwavelength structures for lightsail applications.
• To confirm the optical performance and suitability of the developed lightsail for interstellar missions.

Main Methods:

• Fabrication of a two-layer dielectric lightsail with photonic crystal/metasurface structure on a 4" wafer.
• Achieving broadband reflectivity over the Doppler-shifted laser wavelength range.
• Developing reliable nanofabrication techniques for macroscopic areas.
• Systematic characterization of the optical performance of the lightsail.

Main Results:

• Broadband reflection exceeding 70% was achieved across the relevant wavelength range.
• The lightsail design, when scaled, has a projected low mass (grams for meter-size).
• Successful demonstration of reliable, large-area fabrication of subwavelength structures.
• Optical performance confirmed suitability for lightsail applications.

Conclusions:

• The developed dielectric lightsail represents a significant advancement for laser-propelled interstellar exploration.
• The precise nanofabrication methods enable scalable production of lightsail components.
• This work overcomes key hurdles in materials and manufacturing for ambitious space missions.