Optical microcavity

About: Optical microcavity is a research topic. Over the lifetime, 2599 publications have been published within this topic receiving 72125 citations. The topic is also known as: optical microcavities.

Nonideal Optical Cavity Structure of Superconducting Nanowire Single-Photon Detector

Abstract: Optical cavity structure has been proven to be a crucial factor for obtaining high detection efficiency in superconducting nanowire single photon detector (SNSPD). Practically, complicated fabrication processes may result in a non-ideal optical cavity structure. The cross-sectional transmission electron microscope (TEM) image of SNSPD fabricated in this study shows unexpected arc-shaped optical cavities which could have originated due to the over-etching of SiO2 layer while defining NbN nanowire. The effects of the arc-shaped optical cavity structure, such as the wavelength dependence of the optical absorption efficiency for different polarization, were analyzed by performing optical simulations using finite-difference time-domain method. The central wavelength of the device is found to exhibit a blue shift owing to the arced cavity structure. This effect is equivalent to the flat cavity with a reduced height. The results may give interesting reference for SNSPD design and fabrication.

Using optical fibre cavities to create multi-atom entanglement by quantum zeno dynamics

Abstract: In this thesis, we show how an optical microcavity setup can create multiparticle entanglement in an ensemble of neutral atoms by means of quantum Zeno dynamics (QZD).Our setup combines an atom chip with a fibre Fabry-Perot (FFP) resonator and allows us to load an ensemble of Rb87 atoms into a single node of an intracavity dipole trap, coupling the atoms strongly and identically to the cavity light field which enables us to perform a quantum non-destructive measurement of their collective state.We realise QZD by modifying the dynamics of the collective state (encoded in atomic hyperfine states addressed with MW radiation) by means of frequent cavity measurements at optical frequency. This QZD is shown to create multiparticle entanglement in a fast and deterministic scheme. To analyse the created states, we reconstruct the symmetric part of the atomic density matrix from 2d measurements of the ensemble's Husimi Q-distribution. We give a time-resolved account of the creation of states with at least 3-11 entangled atoms and fidelity of up to 0.37 with respect to a W state of 36 atoms. Studying the influence of measurement strength and experimental imperfections, we show that our experiments are well described by simple models with no free parameters.This thesis also presents work towards improved FFP cavities. We discuss the problem of frequency splitting of polarisation eigenmodes in cavities made from two fibres microfabricated with a CO2 laser. We show that this effect depends on the symmetry of the microfabricated structures and demonstrate that it can be controlled both at the level of fabrication and when assembling a cavity.

Resonant optical microcavity based on crystalline silicon active layer

Abstract: Crystalline silicon microcavities resonant at 1.1 μm were fabricated by using submicron thick Si membranes from a silicon on insulator substrate. These membranes were composed of a single crystalline Si film layered above and below two thin silicon dioxide layers. The low temperature photoluminescence (PL) of the membranes originated from the electron–hole condensed phase, which is characteristic of ultrapure crystalline silicon. The microcavities are then formed by depositing dielectric mirrors on both sides of the membranes. Optical properties of microcavities are studied by optical transmission and PL spectroscopy. The Si PL spectrum is strongly modified by the cavity: at the resonance the PL linewidth is reduced by a factor 3 and the emission is highly angle dependent.