Thermal Runaway of Silicon‐Based Laser Sails

Laser sail‐based spacecraft—where a powerful Earth‐based laser propels a lightweight outer‐space vehicle—have been recently proposed by the Breakthrough Starshot Initiative as a means of reaching relativistic speeds for interstellar space travel. The laser intensity at the sail required for this tas...

Full description

Saved in:
Bibliographic Details
Published in:Advanced optical materials 2022-10, Vol.10 (19), p.n/a
Main Authors: Holdman, Gregory R., Jaffe, Gabriel R., Feng, Demeng, Jang, Min Seok, Kats, Mikhail A., Brar, Victor W.
Format: Article
Language:English
Subjects:
Absorptivity
Bragg reflectors
Electric fields
Interstellar space
laser propulsion
laser sail
Lasers
Materials science
Materials selection
metasurfaces
Optics
Photon absorption
Refractivity
Sails
Silicon
Space flight
Space vehicles
Temperature dependence
Thermal management
Thermal runaway
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Laser sail‐based spacecraft—where a powerful Earth‐based laser propels a lightweight outer‐space vehicle—have been recently proposed by the Breakthrough Starshot Initiative as a means of reaching relativistic speeds for interstellar space travel. The laser intensity at the sail required for this task is at least 1 GW m−2 and, at such high intensities, thermal management of the sail becomes a significant challenge even when using materials with low linear absorption coefficients. Silicon is proposed as one leading candidate material for the sail due to its low sub‐bandgap absorption and high index of refraction, which allows for low‐mass‐density designs. However, here it is shown that the temperature‐dependent linear absorption of silicon can lead to thermal runaway at temperatures above 400–500 K for even the most optimistic viable assumptions of the material quality. Additionally, above a design‐specific threshold laser intensity, nonlinear two‐photon absorption triggers thermal runaway regardless of initial temperature. Resonator‐based designs, which concentrate the field, exhibit lower threshold intensities than geometries that minimize the electric field such as Bragg reflectors. The Breakthrough Starshot Initiative has set the goal of accelerating a laser‐accelerated probe to 20% the speed of light to reach the nearest star. A primary challenge is preventing the probe from overheating during the acceleration phase. The authors demonstrate why making the sail out of silicon carries particular challenges and call for other materials to be investigated further.
ISSN:2195-1071
2195-1071
DOI:10.1002/adom.202102835