High mechanical bandwidth fiber-coupled Fabry-Perot cavity

Abstract

Fiber-based optical microcavities exhibit high quality factor and low mode volume resonances that make them attractive for coupling light to individual atoms or other microscopic systems. Moreover, their low mass should lead to excellent mechanical response up to high frequencies, opening the possibility for high bandwidth stabilization of the cavity length. Here, we demonstrate a locking bandwidth of 44 kHz achieved using a simple, compact design that exploits these properties. Owing to the simplicity of fiber feedthroughs and lack of free-space alignment, this design is inherently compatible with vacuum and cryogenic environments. We measure the transfer function of the feedback circuit (closed-loop) and the cavity mount itself (open-loop), which, combined with simulations of the mechanical response of our device, provide insight into underlying limitations of the design as well as further improvements that can be made.

Cavity-Enhanced Photon Emission from a Single Germanium-Vacancy Center in a Diamond Membrane

“…In summary, we demonstrate coupling of a single Ge-V center in a diamond membrane to a "diamondlike" mode of an open-cavity system, resulting in an 31 +11 −15 times increase in the spectral density of single-photon emission. Moving forward, stable cryogenic operation at the ZPL frequency should be achievable using readily available cavity-locking techniques [44]; such resonant coupling would lead to a projected Purcell enhancement similar to what has been achieved for N-V centers in open cavities [17] with a much larger reduction in the excited-state lifetime. This could be further improved by reducing the 064016-5 cavity mode volume via the mirror radius of curvature, where a shallow mirror with a R ≈ 5 μm would increase the enhancement by a factor of 5 [45].…”

Cryogenic platform for coupling color centers in diamond membranes to a fiber-based microcavity

“…Fiber-based optical resonators with finesse values in the range of 10 5 are feasible with current technology. A more rigid design of the experimental insert [61] and advanced locking techniques combined with higher-order low-pass filters in the electronic lock [62] circuit should enable the stabilization of cavities with finesse values of about 2 × 10 4 [63]. This raises the cavity quality factor to 4.1 × 10 5 for the smallest accessible effective cavity length of about 3.5 μm and, therefore, boosts the single emitter Purcell factor to about 144 with a near-unit collection efficiency of = F p ∕(1 + F p ) = 99.3 %, reaching the strong coupling regime.…”

Correlated photon-pair generation in a liquid-filled microcavity

“…We have constructed a Fabry-Perot microcavity composed of a micromachined and coated endfacet of an optical fiber as one mirror [21,[25][26][27][28][29][30][31][32] and a conventional planar mirror with identical coating as the second mirror (see figure 1). The length of the cavity is L=38.4 μm and the finesse is p = + =  F T L 12 500 500 ( ) with a nominal mirror transmission of T=100 ppm and intracavity losses of L 100 ppm  per mirror.…”