Photoacoustic gas detector

• US 8,359,904 B2
• Filed: 10/21/2010
• Issued: 01/29/2013
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Thales SA
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation), Thales SA
• Inventors: Nicoletti, Sergio, Andreucci, Philippe, Gidon, Serge, Marcadet, Xavier, Carras, Mathieu, Brun, Mickal
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): ROY, PUNAM P
• Application Number:
  US12/909,271
• Publication Number:
  US 20110088453A1
• Time in Patent Office: 831 Days
• Field of Search: 73/240.2, 356/436, 356/437
• US Class Current: 73/24.02
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G01N 2021/1704 in gases
• CPC Class Codes: G01N 2021/1708 with piezotransducers probes for investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves G01N29/24
• CPC Class Codes: G01N 21/1702 with opto-acoustic detection, e.g. for gases or analysing solids
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046

Abstract

A photoacoustic detection device including a nanophotonic circuit including a plurality of semiconductor lasers capable of emitting a different frequencies; input couplers connected to optical waveguides; a multiplexer; an output optical waveguide, emerging into a recess; a tuning fork having its free arms arranged at the output of the output optical waveguide; and means for detecting the vibration of the tuning fork, all these elements being assembled in a monolithic component.

Claims

1. A photoacoustic detection device comprising a nanophotonic circuit comprising:

a plurality of laser diodes (7) capable of emitting at different frequencies;

input couplers (9) connected to optical waveguides;

a multiplexer (13);

an output optical waveguide (15), emerging into a recess;

a tuning fork (18) having its free arms arranged at the level of the output optical waveguide; and

means for detecting the vibration of the tuning fork,

all these elements being assembled in a monolithic component.

2. The device of claim 1, wherein the output of the waveguide is provided with focusing means (16).

3. The device of claim 1, wherein the structure comprising all the lasers is formed in a chip added on a hollowed extension of the support of the nanophotonic circuit.

4. The device of claim 1, wherein the structure comprising all the lasers is directly formed in a multilayer added on the support of the nanophotonic circuit.

5. The device of claim 1, wherein the lasers are of QCL type.

6. The device of claim 1, wherein the cores (11) of the optical waveguides and the arms of the tuning fork (18) are formed from a same material layer (4).

7. The device of claim 6, wherein said material layer rests on a structure of semiconductor-on-insulator type and, at the level of the waveguides, is coated with a cladding layer of same nature as the upper layer of the structure of semiconductor-on-insulator type and, at the level of the tuning fork arms, is suspended above a recess.

8. The device of claim 6, wherein the upper semiconductor layer of the structure of semiconductor-on-insulator type is a silicon layer, and the cores of the optical waveguides as well as the tuning fork arms are made of germanium.

9. The device of claim 6, wherein the upper surface of the structure of semiconductor-on-insulator type is coated with a silicon nitride layer, the cores of the optical waveguides and the arms of the tuning fork are made of silicon, and the cladding layer also is a silicon nitride layer.

10. The device of claim 1, further comprising electronic means for detecting the vibrations of the tuning fork.

11. The device of claim 10, wherein the detection means measure the voltages generated by a piezoelectric effect generated by the material of the tuning fork.

12. The device of claim 10, wherein the detection means comprise electrodes capacitively coupled to the arms of the tuning fork.

13. A photoacoustic detection method and device, comprising the steps of:

forming on a substrate (30) a first layer (31) and a second layer (32), the first layer (31) being selected from among the materials comprising Si, MgF₂, CaF₂, SrF₂, BaF₂, PbF₂, CdF, GaAs, AlGaAs, InP, InAs, InSb, ZnS, CdTe, and Al₂O₃, the second layer (32) being selected from among the materials comprising MgF₂, CaF₂, SrF₂, BaF₂, PbF₂, CdF, GaAs, AlGaAs, InP, InAs, InSb, ZnS, CdTe, and Al₂O₃;

etching the second layer to form active photonic components and especially a waveguide element (15) and a tuning fork element (18);

forming an upper cladding layer (33) above the waveguide portion (15), selected from among the materials comprising MgF₂, CaF₂, SrF₂, BaF₂, PbF₂, CdF, GaAs, AlGaAs, InP, InAs, InSb, ZnS, CdTe, and Al₂O₃;

forming a cavity under the tuning fork;

forming QCL lasers and inserting them into the substrate.