The strong evanescent field around ultrathin unclad optical fibers bears a high potential for detecting, trapping, and manipulating cold atoms. Introducing such a fiber into a cold-atom cloud, we investigate the interaction of a small number of cold cesium atoms with the guided fiber mode and with the fiber surface. Using high resolution spectroscopy, we observe and analyze light-induced dipole...

This paper presents an analytic approach to spontaneous emission in resonators with distributed Bragg reflectors (DBR’s). The foundation of our analysis is the hard mirror (or penetration depth) approximation, which we extend to radiation with both angular and frequency distributions. This has allowed us to derive approximate analytic expressions for the divergence angle of the spontaneous emis...

We experimentally investigate the spontaneous emission (SE) rates of single InAs quantum dots embedded in GaAs photonic nanowires. For a diameter leading to the optimal confinement of the fundamental guided mode HE11, the coupling to HE11 dominates the SE process and an increase of the SE rate by a factor of 1.5 is achieved. When the diameter is decreased, the coupling to this mode vanishes rap...

In a multimode photonic-crystal waveguide, we observe strong enhancement of the photoluminescence of embedded quantum dots at the edges of the so-called mini-stopband that were opened by Bragg diffraction between two guided modes. Taking into account light collection, we relate this observation to the singular photon density of states that is characteristic of a one-dimensional photon system. F...

The optical klystron enhancement to a self-amplified spontaneous emission free electron laser has been studied in theory and in simulations and has been experimentally demonstrated on a single-pass high-gain free electron laser, the FERMI FEL-1, in 2014. The main concept consists of two undulators separated by a dispersive section that converts the energy modulation induced in the first undulat...

We devise new optical antennas that reduce the excited-state radiative lifetimes of emitters to the order of 100 fs while maintaining quantum efficiencies of about 80% at a broadband operation. Here, we combine metallic nanoparticles with planar dielectric structures and exploit design strategies from plasmonic nanoantennas and concepts from cavity quantum electrodynamics to maximize the local ...

Light emitters in a single-mode nanolaser interact with the same cavity field, that gives rise to polarization correlations which transform mode. Usually these are ignored, however, collective phenomena can lead distinct sub- and superradiance, whose fully quantum description is challenging. Here, we develop simple yet rigorous picture of radiative transitions nanolasers accounts for correlatio...

The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, wh...

We suggest a source of polarization-entangled photon pairs based on a cross-shaped plasmonic nanoantenna driven by a single quantumdot. The integration of the nanoantennawith ametalmirror overcomes the fundamental tradeoff between the spontaneous emission (SE) enhancement and the extraction efficiency typical ofmicrocavityand nanowire-based architectures.With a very high extraction efficiency o...