A hemispherical, high-solid-angle optical micro-cavity for cavity-QED studies

Abstract

We report a novel hemispherical micro-cavity that is comprised of a planar integrated semiconductor distributed Bragg reflector (DBR) mirror, and an external, concave micro-mirror having a radius of curvature 50 microm. The integrated DBR mirror containing quantum dots (QD), is designed to locate the QDs at an antinode of the field in order to maximize the interaction between the QD and cavity. The concave micro-mirror, with high-reflectivity over a large solid-angle, creates a diffraction-limited (sub-micron) mode-waist at the planar mirror, leading to a large coupling constant between the cavity mode and QD. The half-monolithic design gives more spatial and spectral tuning abilities, relatively to fully monolithic structures. This unique micro-cavity design will potentially enable us to both reach the cavity quantum electrodynamics (QED) strong coupling regime and realize the deterministic generation of single photons on demand.

GaN hemispherical micro-cavities

“…16,18,19 On the contrary, optical microcavities of spherical or hemispherical geometries are ideal platforms for WGMs owing to outstanding three-dimensional (3D) optical confinement. 20 Spherical or hemispherical microcavities are typically fabricated by the melting of silica glass, 21,22 using liquid microdroplets levitated in air or self-assembled polymer hemispherical cavities on hydrophobic DBRs through surface tension. [23][24][25][26] Although lasing actions have been demonstrated from these spherical/hemispherical cavities through addition of quantum dots or organic dyes as gain media, 27 the control and maintenance over the dimensions and stabilities of such microcavities remain challenging.…”

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

“…In the following, we briefly summarize micro-machining approaches that have been used to fabricate hybrid-integrated cavities, with some emphasis on recent efforts aimed at the eventual monolithic integration of mirrors and cavities with other functional devices. [73], (b) a laser machined fiber end [12], (c) array of concave features made by FIB milling [11], (d) two silicon micro-mirrors fabricated by dry etching [74], (e) array of cantilever based micro-mirrors [75], (f) and a waveguide connected buckled-dome microcavity [16].…”

“…For example, early work by Prakash et al [76] used electrochemical growth on a template of latex microspheres to form gold-based hemispherical mirrors. Cui et al [73] employed a bubble-trapping method to form hemispherical surfaces on a glass substrate, onto which a dielectric mirror was deposited ( Figure 5 (a)). Steinmetz et al [72] detached dielectric mirrors previously deposited on a spherical surface (ball lens or microlens) and glued them to the end of an optical fiber.…”

Transverse-mode coupling effects in scanning cavity microscopy

“…Different techniques have been developed to produce concave, near-spherical profiles as micro-mirror substrates, including CO 2 laser machining [8,[18][19][20][21], chemical etching [22,23], focused ion beam milling [24,25], and thermal reflow [26,27]. While the achieved shape accuracy (∼2 nm) and surface roughness (<0.2 nm) is at a remarkable level [19,[28][29][30], even nano-scale deviations of the surface from the ideal spherical shape affect the mode structure.…”