Abstract: The invention relates to a device and method for detecting an acoustic wave propagating toward a membrane, the membrane carrying a waveguide comprising an optical cavity defining a resonant frequency. Under the effect of a vibration of the membrane, the resonance frequency of the optical cavity varies. The device includes a light source for directing a light wave into the optical cavity, and a servo circuit for servo-controlling the wavelength of the light wave to the resonant wavelength of the optical cavity. Monitoring the variation in the wavelength of the light wave allows an amplitude of the acoustic wave to be estimated.

Abstract: The invention is a device and method for detecting an analyte in a medium. An exciting light source produces an exciting light wave, which propagates to the medium and heats the latter. The device comprises a transducer for detecting the heating of the medium. According to one embodiment, the transducer is a thermal transducer, configured to detect a variation in the temperature of the medium. According to another embodiment, the transducer is an acoustic transducer, configured to detect a photoacoustic wave propagating from the medium. Whatever the embodiment, the transducer employs a membrane, on which a waveguide is placed. The waveguide comprises a resonant optical cavity. Transduction is achieved by analyzing a variation in a resonant wavelength of the optical cavity.