Optomechanical spring enhanced mass sensing

Abstract

On-chip nano-optomechanical systems (NOMS) have demonstrated a zeptogram-level mass sensitivity and are promising candidates for low-cost implementations in areas such as metabolite quantitation and chemical analysis. High responsivity and sensitivity call for substantial optomechanical coupling and cavity finesse, resulting in detuning-dependent stiffness and mechanical damping via optomechanical back-action. Since mass loading (or temperature or force change) can alter both mechanical and cavity properties, mechanical frequency shifts induced by loading can encompass both effects. Precision sensing requires understanding and quantifying the source of the frequency tuning. Here, we show the deconvolution of direct loading and optomechanical stiffness change on the mechanical eigenfrequency as a function of detuning for a nano-optomechanical sensor in gaseous sensing experiments. Responses were generally dominated by shifts in optical stiffness and resulted in a mass loading signal amplification by as much as a factor of 2.5. This establishes an alternative possible route toward better mass sensitivity in NOMS while confirming the importance of incorporating optical stiffness effects for precision mass sensing.

Opto-Mechanical Photonic Crystal Cavities for Sensing Application

“…However, thermo-optical noise caused by the instability of coupling methods, for example tapered fiber coupling, limits their sensing resolution to the level of picograms. To reduce this noise, the integrated bus waveguide [133] coupling may be an alternative and effective scheme. For PhC cavities based optomechanical mass sensors, most research has focused on the numerical analysis [134][135][136], as shown in Figure 22a.…”

Multimode Optomechanical Weighting of a Single Nanoparticle

“…The disk combines an experimental mass detection limit of 40 MDa with a capture area of 380 μm 2 , two decades above recent realizations. 11,12,14 We demonstrate dual mechanical and optical sensing, as well as multimode mechanical sensing, obtaining multiple concomitant informations on the deposited particles in real time. The optomechanical device is optimized to weight masses up to tens of GDa, and we were able to measure and quantitatively analyze the deposition of individual nanoparticles that mimic intermediate viruses, be it by their size and mass (150 nm diameter nanoparticles) or by their elastic modulus (soft latex nanoparticles).…”

“…Among them, all-optical techniques bring about a wide-band and low-noise-actuation capacity, − together with an outstanding sensitivity to mechanical motion, which are central advantages in working with high-frequency resonators of small size. Such optical techniques naturally benefit from optomechanical concepts, , and miniature optomechanical resonators were recently investigated for the mechanical sensing of objects of nanoscale mass, − with an improving level of control. This culminated in ref , where single-particle nanomechanical mass spectrometry in the megadalton range was demonstrated using an optomechanical nanoram device with a capture area of 4.5 μm 2 .…”

Cavity Optomechanical Sensing in the Nonlinear Saturation Limit

“…The latter mode is particularly interesting since it is resilient to low‐frequency noise. It has been widely employed in many areas, ranging from force [ 6 ] and mass sensing, [ 11,12 ] inertial sensing, [ 7,13,14 ] electro‐ [ 15 ] and magnetometry, [ 8 ] acoustic sensing, [ 16–18 ] atomic force microscopy, [ 19 ] refractive index sensing, [ 20 ] and chemical and bio‐sensing for tracking chemical reactions and molecular dynamics. [ 21–23 ] Most sensing experiments make use of feedback control such as the Pound–Drever–Hall (PDH) technique [ 24 ] to lock the laser to the cavity mode.…”