Bolometer with high spectral sensitivity

Patent metadata

Field	Value
Publication number	US-9733180-B2
Application number	US-201615287175-A
Country	US
Kind code	B2
Filing date	Oct 6, 2016
Priority date	Oct 9, 2015
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A bolometric detector including an absorption membrane, for converting an incident electromagnetic radiation into heat; and a reflector, for reflecting to the absorption membrane part of the incident electromagnetic radiation having passed there through, is provided. The bolometric detector includes a non-metallic layer, situated between the absorption membrane and the reflector, having a series of index jumps, so as to form a network resonating at a wavelength of interest λ 0 ; the mean pitch of the network is less than λ 0 ; and the optical distance between the absorption membrane and the reflector is substantially equal to a multiple of λ 0 /2.

First claim

The invention claimed is:

1. A bolometric detector including at least one pixel, the at least one pixel comprising:
an absorption membrane configured to convert incident electromagnetic radiation into heat;
a reflector configured to reflect to the absorption membrane part of the incident electromagnetic radiation having passed through the absorption membrane; and
a non-metallic structured layer disposed between the absorption membrane and the reflector and being thermally insulated from the absorption membrane, the structured layer having a series of optical index jumps between a first optical index and a second optical index in a plane parallel to an upper surface of the absorption membrane, forming a resonating network at a wavelength of interest (λ 0 ),
wherein a mean pitch of the resonating network is less than λ 0 , and
wherein an optical distance between the absorption membrane and the reflector is substantially equal to a multiple of λ 0 /2.

2. The bolometric detector according to claim 1 , wherein a difference between the first optical index and the second optical index is greater than 0.5.

3. The bolometric detector according to claim 1 , wherein the mean pitch of the network is between λ 0 /2 and λ 0 .

4. The bolometric detector according to claim 1 , wherein the resonating network is a periodic network.

5. The bolometric detector according to claim 1 ,
wherein the resonating network is a pseudo-periodic network, having variations in a shape of an elementary pattern of said resonating network, and
wherein a coverage rate of the elementary pattern relative to a mean shape of the elementary pattern is between 90% and 99%.

6. The bolometric detector according to claim 1 , wherein the optical index jumps are distributed along directions corresponding to two perpendicular directions in the plane parallel to the absorption membrane.

7. The bolometric detector according to claim 1 , wherein the optical index jumps are distributed along a direction corresponding to a single direction in the plane parallel to the absorption membrane.

8. The bolometric detector according to claim 1 ,
wherein each index jump in said series is constituted by an interface between a first material and a second material, and
wherein one of the first and second materials is a vacuum or a gas.

9. The bolometric detector according to claim 1 , wherein a gap between the structured layer and the absorption membrane is less than λ 0 /2.

10. The bolometric detector according to claim 1 , further comprising a low-index layer covering the structured layer and being spaced apart from the absorption membrane.

11. The bolometric detector according to claim 1 , wherein the at least one pixel comprises a plurality of pixels, at least two pixels in said plurality differing by a mean shape of elementary patterns and being configured to detect different wavelengths of interest.

12. The bolometric detector according to claim 11 , wherein each pixel in said plurality includes a corresponding low-index layer covering the structured layer of said each pixel and being spaced apart from a corresponding absorption membrane of said each pixel, a thickness of each corresponding low-index layer being chosen so as to maintain an optical distance between the corresponding absorption membrane and a corresponding reflector that is substantially equal to a multiple of λ 0 /2.

13. The bolometric detector according to claim 12 , wherein at least two of said each corresponding low-index layer have thicknesses that are different from each other.

14. The bolometric detector according to claim 1 , further comprising an intermediate non-metallic layer extending between the reflector and the structured layer.

15. A gas sensor comprising an infrared source configured to emit an electromagnetic radiation inside a cavity, wherein the cavity contains a bolometric detector according to claim 1 .

Assignees

• Commissariat Energie Atomique

Inventors

• Boutami Salim
• Eloi Fabien
• Hazart Jerome
• Yon Jean-Jacques

Classifications

• G01J5/0801

  Means for wavelength selection or discrimination · CPC title

• G01J5/024 Primary

  Special manufacturing steps or sacrificial layers or layer structures · CPC title

• G01J2005/106

  Arrays · CPC title

• G01J5/34

  using capacitors, e.g. pyroelectric capacitors · CPC title

• G01N21/3504 Primary

  for analysing gases, e.g. multi-gas analysis · CPC title