Spontaneous emission

About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.

Cold-atom physics using ultrathin optical fibers: light-induced dipole forces and surface interactions.

Abstract: 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 forces, van der Waals interaction, and a significant enhancement of the spontaneous emission rate of the atoms. The latter can be assigned to the modification of the vacuum modes by the fiber.

Light trapped in a photonic dot: Microspheres act as a cavity for quantum dot emission

Abstract: Optical microcavities that confine the propagation of light in all three dimensions (3D) are fascinating research objects to study 3D-confined photon states, low-threshold microlasers, or cavity quantum electrodynamics of quantum dots in 3D microcavities. A challenge is the combination of complete electronic confinement with photon confinement, e.g., by linking a single quantum dot to a single photonic dot. Here we report on the interplay of 3D-confined cavity modes of single microspheres (the photonic dot states) with photons emitted from quantized electronic levels of single semiconductor nanocrystals (the quantum dot states). We show how cavity modes of high cavity finesse are switched by single, blinking quantum dots. A concept for a quantum-dot microlaser operating at room temperature in the visible spectral range is demonstrated. We observe an enhancement in the spontaneous emission rate; i.e., the Purcell effect is found for quantum dots inside a photonic dot.

Quantum efficiency and excited-state relaxation dynamics in neodymium-doped phosphate laser glasses

Abstract: Radiometrically calibrated spectroscopic techniques employing an integrating-sphere detection system have been used to determine the fluorescence quantum efficiencies for two commercially available Nd3+-doped phosphate laser glasses, LG-750 and LG-760. Quantum efficiencies and fluorescence lifetimes were measured for samples with various neodymium concentrations. It is shown that the effects of concentration quenching are accurately described when both resonant nonradiative excitation hopping (the Burshtein model) and annihilation by cross relaxation are accounted for by Forster–Dexter dipole–dipole energy-transfer theory. The Forster–Dexter critical range for nonradiative excitation hopping was found to be RDD = 11 A, while the critical range for cross relaxation was close to RDA = 4 A in these glasses. The quantum efficiency at low Nd3+ concentrations was (92 ± 5)%, implying a nonradiative relaxation rate of 210 ± 150 s−1 for isolated ions. Improved values for the radiative lifetimes and the stimulated emission cross sections for these glasses were also deduced from the measurements.