US 12,228,498 B2
Photoacoustic or photothermal detector comprising an optical transducer
Thomas Lauwers, Grenoble (FR); Skandar Basrour, Grenoble (FR); Jean-Guillaume Coutard, Grenoble (FR); Alain Gliere, Grenoble (FR); and Guillaume Laffont, Grenoble (FR)
Assigned to COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, Paris (FR); UNIVERSITE GRENOBLE ALPES, Saint Martin d'Heres (FR); CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE, Paris (FR); and INSTITUT POLYTECHNIQUE DE GRENOBLE, Grenoble (FR)
Appl. No. 17/757,935
Filed by COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, Paris (FR); UNIVERSITE GRENOBLE ALPES, Saint Martin D'heres (FR); CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE, Paris (FR); and INSTITUT POLYTECHNIQUE DE GRENOBLE, Grenoble (FR)
PCT Filed Dec. 24, 2020, PCT No. PCT/EP2020/087866
§ 371(c)(1), (2) Date Jun. 23, 2022,
PCT Pub. No. WO2021/130364, PCT Pub. Date Jul. 1, 2021.
Claims priority of application No. 19 15696 (FR), filed on Dec. 27, 2019.
Prior Publication US 2022/0364981 A1, Nov. 17, 2022
Int. Cl. G01N 21/31 (2006.01); G01N 21/17 (2006.01)
CPC G01N 21/1702 (2013.01) [G01N 21/1717 (2013.01); G01N 21/31 (2013.01); G01N 2021/1704 (2013.01); G01N 2021/1706 (2013.01); G01N 2021/1731 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A detecting device configured to be applied, via a contact face, against a medium to be analyzed, the analyzed medium being liable to contain an analyte, which absorbs light at an absorption wavelength, the device comprising:
an aperture formed in the contact face;
a first light source configured to emit a first light wave, which is pulsed or amplitude-modulated at a first frequency, in an excitation spectral band comprising the absorption wavelength, the device being configured so that the first light wave propagates through the aperture toward the analyzed medium; and
a transducer configured to measure a response of the medium following periodic heating of the medium resulting from absorption, by the analyte, of some of the first light wave, wherein the transducer includes
a membrane, carrying a waveguide, the waveguide comprising a first reflector and a second reflector, each of the first and second reflectors reflecting light in a reflection spectral band, the first reflector and the second reflector being spaced apart from each other so as to form a resonant optical cavity, the resonant optical cavity defining a resonant wavelength in the reflection spectral band such that the waveguide:
transmits light at the resonant wavelength; and
reflects light, in the reflection spectral band, not of the resonant wavelength,
wherein the transducer further comprises
a second source of laser light, configured to emit a second light wave, in the reflection spectral band, into the waveguide;
a photodetector, arranged to detect a light wave transmitted by the waveguide at the resonant wavelength; and
a servo circuit connected to the photodetector and configured to determine a periodic time-dependent modulation of the resonant wavelength of the resonant optical cavity,
wherein the waveguide is formed directly on the membrane;
the membrane is configured to deform periodically under an effect of the periodic heating of the medium so that the resonant wavelength is periodically modulated;
the servo circuit further comprises a servo loop, connected to the second light source, and configured to servo-control a wavelength of the second light wave emitted by the second light source to the resonant wavelength of the resonant optical cavity; and
the second light source is different than the first light source.