US Patent 9798218 Switchable directional infrared radiation source

A source of directional radiation in an IR band comprises at least a substrate and an external layer comprising controllable cells made of a metal insulator transition material that changes phase depending on its temperature relative to a temperature at which the corresponding wavelength is located in the IR band and that possesses a crystalline phase and an amorphous phase, and control means for controlling the phase change of the cells so as to form in this external layer a diffraction grating when the cells are controlled to the amorphous phase, in order thus to obtain a switchable directional source.