Integrated optical force sensors using focusing photonic crystal arrays

Abstract

Mechanical oscillators are at the heart of many sensor applications. Recently several groups have developed oscillators that are probed optically, fabricated from high-stress silicon nitride films. They exhibit outstanding force sensitivities of a few aN/Hz${}^{1/2}$ and can also be made highly reflective, for efficient detection. The optical read-out usually requires complex experimental setups, including positioning stages and bulky cavities, making them impractical for real applications. In this paper we propose a novel way of building fully integrated all-optical force sensors based on low-loss silicon nitride mechanical resonators with a photonic crystal reflector. We can circumvent previous limitations in stability and complexity by simulating a suspended focusing photonic crystal, purely made of silicon nitride. Our design allows for an all integrated sensor, built out of a single block that integrates a full Fabry-Pérot cavity, without the need for assembly or alignment. The presented simulations will allow for a radical simplification of sensors based on high-Q silicon nitride membranes. Our results comprise, to the best of our knowledge, the first simulations of a focusing mirror made from a mechanically suspended flat membrane with subwavelength thickness. Cavity lengths between a few hundred $\mu$m and mm should be directly realizable.

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• Cavity Optomechanics
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• From membrane-in-the-middle to mirror-in-the-middle with a high-reflectivity sub-wavelength grating
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Cited by in corpus (10)

• Centimeter-scale suspended photonic crystal mirrors
• Cavity Optomechanics with Photonic Bound States in the Continuum
• Microcavities with suspended subwavelength structured mirrors
• Phononically shielded photonic-crystal mirror membranes for cavity quantum optomechanics
• Integrated microcavity optomechanics with a suspended photonic crystal mirror above a distributed Bragg reflector
• Suspended silicon nitride thin films with enhanced and electrically tunable reflectivity
• Profilometry and stress analysis of suspended nanostructured thin films
• Broadband, High-Reflectivity Dielectric Mirrors at Wafer Scale: Combining Photonic Crystal and Metasurface Architectures for Advanced Lightsails
• Electromechanics in vertically coupled nanomembranes
• Long-range optomechanical interactions in SiN membrane arrays