Speaker
Description
Infrared (IR) detectors are essential for applications including environmental monitoring [1], gas spectroscopy [2], and thermal imaging [3], each imposing distinct requirements on sensitivity, speed, and spatial resolution. While several IR detectors are already commercially available, existing technologies still exhibit fundamental trade-offs [4]: photon detectors offer high sensitivity but require cryogenic cooling, while thermal detectors operate at room temperature but are limited by electrical readout noise, constraining their minimum detectable signal.
Mechanical photothermal detectors offer a promising alternative, transducing absorbed radiation into resonance frequency shifts via thermally induced stress relaxation in a mechanical resonator [5]. When combined with optical readout, this approach largely avoids electrical noise sources, enabling operation near the fundamental thermal fluctuation limit [6], at room temperature.
Here, we explore a new approach to photothermal IR detection based on multi-mode measurement protocols on a highly stressed SiN resonator. We demonstrate that the absorbed radiation induces mode- and position-dependent frequency shifts and compare experimental results with finite element simulations. We envision that this concept could be extended to infer the spatial profile of a spatially distributed source, offering a promising platform for IR imaging applications.
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[2] C. Chen, Q. Ren and Y. Z. Wang, Review on multi gas detector using infrared spectral absorption technology, Appl. Spectrosc. Rev. 54, 425–444 (2019), https://doi.org/10.1080/05704928.2018.1474766
[3] T. Bamroongshawgasame, X. Zhang and Q. Li, Emerging Trends and Applications in Thermal Imaging Using Infrared Detectors: A Review, IEEE Sens. J. 26, 1520–1532 (2026), https://doi.org/10.1109/JSEN.2025.3635054
[4] A. Rogalski, Infrared detectors: an overview, Infrared Phys. Technol. 43, 187–210 (2002), https://doi.org/10.1016/S1350-4495(02)00140-8
[5] K. Kanellopulos, F. Ladinig, S. Emminger, P. Martini, R. G. West and S. Schmid, Comparative analysis of nanomechanical resonators: sensitivity, response time, and practical considerations in photothermal sensing, Microsystems & Nanoengineering 11, 28 (2025), https://doi.org/10.1038/s41378-025-00879-6
[6] C. Zhang, Z. Louis-Seize, Y. Saleh, M. Brazeau, T. Hodges, M. Turgeon-Roy and R. St-Gelais, Enhanced Bandwidth in Radiation Sensors Operating at the Fundamental Temperature Fluctuation Noise Limit, Nano Lett. 25, 14660–14667 (2025), https://doi.org/10.1021/acs.nanolett.5c03415s