Methods and apparatus for modulating light with phase change materials

US11320647B2 · kind B2 · utility

Assignee

• Massachusetts Institute of Technology · US

Inventors

• Jeffrey Chou · Boston, US
• Vladimir Liberman · Reading, US
• Juejun Hu · Newton, US
• Yifei Zhang · Beijing, CN
• William D. Herzog · Groton, US
• Jason Scott Stewart · Hornell, US
• Christopher Roberts · Burton, US

Key dates

• Filing date: Jan 31, 2019
• Grant date: May 3, 2022
• Expiry date: Oct 10, 2039

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F2203/18
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Alloys of GeSbSeTe (GSST) can be used to make actively tunable infrared transmission filters that are small, fast, and solid-state. These filters can be used for hyperspectral imaging, 3D LIDAR, portable bio/chem sensing systems, thermal emission control, and tunable filters. GSST is a low-loss phase-change material that can switch from a low-index (n=3), amorphous state to a high-index (n=4.5), hexagonal state with low loss (k<0.3) over a wavelength range of 2-10 microns or more. The GSST thickness can be selected to provide pure phase modulation, pure amplitude modulation, or coupled phase and amplitude modulation. GSST can be switched thermally in an oven, optically with visible light, or electrically via Joule heating at speeds from kilohertz to Gigahertz. It operates with reversible and polarization independent transmission switching over a wide incident angle (e.g., 0-60 degrees).