Purcell factor enhanced scattering efficiency in optical microcavities

Scattering processes in an optical microcavity are investigated for the case of silicon nanocrystals embedded in an ultra-high Q toroid microcavity. Using a novel measurement technique based on the observable mode-splitting, we demonstrate that light scattering is highly preferential: more than 99.8% of the scattered photon flux is scattered into the original doubly-degenerate cavity modes. The large capture efficiency is attributed to an increased scattering rate into the cavity mode, due to the enhancement of the optical density of states over the free space value and has the same origin as the Purcell effect in spontaneous emission. The experimentally determined Purcell factor amounts to 883

Fabrication and characterization of erbium-doped toroidal microcavity lasers

Erbium-doped SiO2 toroidal microcavity lasers are fabricated on a Si substrate using a combination of optical lithography, etching, Er ion implantation, and CO2 laser reflow. Erbium is either preimplanted in the SiO2 base material or postimplanted into a fully fabricated microtoroid. Three-dimensional infrared confocal photoluminescence spectroscopy imaging is used to determine the spatial distribution of optically active Er ions in the two types of microtoroids, and distinct differences are found. Microprobe Rutherford backscattering spectrometry indicates that no macroscopic Er diffusion occurs during the laser reflow for preimplanted microtoroids. From the measured Er doping profiles and calculated optical mode distributions the overlap factor between the Er distribution and mode profile is calculated: Gamma=0.066 and Gamma=0.02 for postimplanted and preimplanted microtoroids, respectively. Single and multimode lasing around 1.5 µm is observed for both types of microtoroids, with the lowest lasing threshold (4.5 µW) observed for the preimplanted microtoroids, which possess the smallest mode volume. When excited in the proper geometry, a clear mode spectrum is observed superimposed on the Er spontaneous emission spectrum. This result indicates the coupling of Er ions to cavity modes

An attempt to locate substorm onsets using Pi1 signatures

Pi1 observations, because of their higher frequency, hold the promise of providing better temporal resolution for accurate timing of substorm onsets, thus continuing to be a matter of considerable importance for evaluation of competing substorm mechanisms. In this presentation we show that the same Pi1 signatures detected by the ground magnetometer array can be used also for the spatial location of substorm onsets. We have used data from Antarctic search-coil magnetometers. To locate an ionospheric source of Pi1 signatures we have applied a method of emission tomography that was previously used in seismology. The source image reconstruction algorithm uses scanning of the volume under investigation; for each of the grid points a coherency measure for multi-channel data is calculated. For the source image reconstruction we have introduced a coherency measure, that may be coined the nonlinear semblance. Though the Antarctic stations are elongated in one direction, that is not favorable for tomography methods, the results obtained seems to be very promising for locating substorm onsets with ground magnetometer data

Purcell factor reduced scattering losses in optical microcavities

Scattering induced by silicon nano-particles in a microcavity is investigated for the case of silicon nanocrystal doped microtoroids. A significant enhancement of preferential-scattering into the originally doubly-degenerate cavity eigenmodes is found, exceeding >99.42%

Supporting data for Entanglement between a Diamond Spin Qubit and a Photonic Time-Bin Qubit at Telecom Wavelength

We report on the realization and verification of quantum entanglement between a nitrogen-vacancy electron spin qubit and a telecom-band photonic qubit. First we generate entanglement between the spin qubit and a 637 nm photonic time-bin qubit, followed by photonic quantum frequency conversion that transfers the entanglement to a 1588 nm photon. We characterize the resulting state by correlation measurements in different bases and find a lower bound to the Bell state fidelity of ≥0.77±0.03. This result presents an important step towards extending quantum networks via optical fiber infrastructure

Purcell-Factor-Enhanced Scattering from Si Nanocrystals in an Optical Microcavity

Scattering processes in an optical microcavity are investigated for the case of silicon nanocrystals embedded in an ultra-high-Q toroid microcavity. Using a novel measurement technique based on the observable mode splitting, we demonstrate that light scattering is highly preferential: more than 99.8% of the photon flux is scattered into the original doubly degenerate cavity modes. The large capture efficiency is shown to result from the Purcell enhancement of the optical density of states over the free space value, an effect that is more typically associated with spontaneous emission. The experimentally determined Purcell factor has a lower bound of 171