Sensing Nanoparticles with a Cantilever-Based Scannable Optical Cavity of Low Finesse and Sub-λ3Volume

Fabrication of mirror templates in silica with micron-sized radii of curvature

“…Only a few fabrication methods are known to produce concave microoptics with radii of curvature R 5 lm, e.g., focussed ion beam (FIB) milling, 8,9 femtosecond laser wet etching 10 and proximity-effect-assisted reflow techniques. 11 For an optical cavity with total round-trip losses L tot and ultra-high finesse F % p=L tot % 10 5 , acceptable round-trip scattering losses are below S % ð4pr=kÞ 2 ¼ 30 ppm, setting the upper limit for the surface roughness to a demanding r ¼ 2…6 Å in the VIS-NIR spectral range.…”

Tunable Open‐Access Microcavities for Solid‐State Quantum Photonics and Polaritonics

“…It is worthwhile to mention that the linewidth broadening induced by mechanical vibrations is not related to any intrinsic property of the studied physics, as the lifetimes of cavity photons and emitters, usually in pico to nanoseconds, are much shorter than the vibrating cycle. Nevertheless, most of the measurements for quantum emitters and polaritons require long integration time to reach an acceptable signal to noise ratio, and cavity stabilization is required if the cavity is designed for a Q ‐factor sufficiently high that could be seriously influenced by the vibration . One of the most commonly used method of passive stabilization is touching the concave and planar mirrors, which greatly reduces their relative motion .…”

On-chip High-finesse Fabry-Perot Microcavities for Optical Sensing and Quantum Information

“…In related work, Mader et al [51] formed a high-finesse cavity using a spherical mirror on a fiber end-facet, which could be scanned to image and characterize nanoparticles attached to the opposite (planar) mirror of the cavity. Finally, Kelkar et al [53] used a low-VM spherical mirror cavity to sense single nanoparticles. While at an early stage of development, spherical-mirror FPC sensors hold great promise for the detection of small particles, possibly even down to the single molecule level [38,52].…”

“…This modification was historically treated by Purcell using a semi-classical approach, with the essential results subsequently confirmed by rigorous quantum mechanical treatments [23]. For example, assuming an atom located at a field maximum (in an otherwise empty cavity, such that refractive index n =1) and with its electric dipole aligned to the cavity mode field, and also assuming the atomic transition is exactly matched to a cavity resonance and with γ < κ [53,71], then the enhancement of the radiative decay rate is given by the so-called Purcell factor:…”

“…In the case of solid-state emitters, which have relatively large g, this implies that small VM is particularly critical (i.e. since increased k implies reduced Q) [53,71]. …”