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Resonant optical transduction for photoacoustic detection

Author(s): T. Lauwers, A. Glière, S. Basrour

Doc. Source: SPIE Photonics West 2020 - Optoelectronics, photonic materials and devices

A highly sensitive optical transduction system suitable for photoacoustic trace gas detection is presented. The system includes a thin deformable hinged cantilever assembled on an optical fiber to form a Fabry-Perot cavity, whose length varies according to the acoustic pressure disturbance. Consequently, the optical power of the reflected light fluctuates at acoustic frequencies around the working point, which is stabilized to prevent from environmental drift of the interference fringes. The resonant mechanical structure proposed in this study shows a spectral response in good agreement with FEM simulation, good linearity and stability, with a noise equivalent pressure of 12 𝜇Pa/√Hz.