SWITCHABLE DIRECTIONAL INFRARED RADIATION SOURCE

• US 20150293428A1
• Filed: 11/27/2013
• Published: 10/15/2015
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique, Institut D'Optique Graduate School, Universite Paris - Sud
• Original Assignee: Centre National De La Recherche Scientifique, Institut D'Optique Graduate School
• Inventors: Benisty, Henri, Ben-Abdallah, Philippe, Coutrot, Anne-Lise, Besbes, Mondher
• Granted Patent: US 9,798,218 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 27/42 Diffraction optics , i.e. systems including a diffractive element being designed for providing a diffractive effectG02B27/60 takes precedence
• CPC Class Codes: G02B 5/1828 having means for producing variable diffraction controlling the direction of light by means of one or more diffracting elements G02B26/0808; acousto-optical elements G02F1/11, G02F1/33; electro- or magneto-optical diffraction G02F1/292, G02F1/2955
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 1/035 in an optical waveguide structure
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 2/02 Frequency-changing of light, e.g. by quantum counters
• CPC Class Codes: G02F 2203/11 involving infrared radiation

Abstract

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.

Claims

1. A source of directional radiation in an IR band, comprising 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 Tc 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 said external layer a diffraction grating when the cells are controlled to the amorphous phase, in order to obtain a switchable directional source.

2. The radiation source as claimed in claim 1, wherein the diffraction grating is periodic.

3. The radiation source as claimed in claim 1, wherein the control means are electrical.

4. The radiation source as claimed in claim 1, wherein the control means are able to control groups of cells, each group comprising a variable number of cells.

5. The radiation source as claimed in claim 1, characterized in that it comprises means for supervising the control means, which means are configured to modify the spatial characteristics of the diffraction grating, and thus to obtain a switchable directional source the emission direction of which may be modulated.

6. The radiation source as claimed in claim 1, wherein the substrate is made of a material able to support a surface mode.

7. The radiation source as claimed in claim 1, wherein the controllable cells are bounded by a thermal and electrical insulator.

8. The radiation source as claimed in claim 7, wherein the cell/substrate insulator is a layer of SiO₂.

9. The radiation source as claimed in claim 7, wherein the substrate is made of the same MIT material as that of the external layer.

10. The radiation source as claimed in claim 1, wherein the electrical control means comprise a generator of electrical pulses.

11. The radiation source as claimed in claim 1, wherein the external layer comprising the controllable cells comprises a uniform external layer made of said metal insulator transition material and a subjacent underlayer of spatially variable thermal conductivity intended to form said cells in the external underlayer depending on said spatial variation, and in that the control means for collectively controlling the cells consist of a single thermal or electrical control that results in modulated thermal heating through the intervention of the underlayer of spatially variable thermal conductivity.

12. The radiation source as claimed in claim 1, wherein the metal insulator transition material belongs to the group consisting of vanadium oxides or barium titanates or lanthanum perovskites.