By performing cryogenic laser spectroscopy under scanning probe electrode that induces local electric field, we have resolved two individual fluorescent molecules separated by 12 nanometers in an organic crystal. The two molecules undergo strong coherent dipole-dipole coupling that produces entangled sub- and superradiant states. Under intense laser illumination, both molecules are excited via two-photon transition, and the fluorescence from this doubly excited system displays photon bunching. Our experimental scheme can be used to optically resolve molecules at the nanometer scale and to manipulate the degree of entanglement among them.
Spontaneous emission of europium ions embedded in dielectric nanospheres
We measure fluorescence lifetimes of emitters embedded in isolated single dielectric nanospheres. By varying the diameters of the spheres from 100 nm to 2 mum and by modifying their dielectric surrounding, we demonstrate a systematic change of paradigm in the spontaneous emission rate, as we cross the border from the superwavelength regime of Mie resonances to the nanoscopic realm of Rayleigh scattering. Our data show inhibition of the spontaneous emission up to 3 times and are in excellent agreement with the results of analytical calculations.
Influence of a sharp fiber tip on high-Q modes of a microsphere resonator
We investigate the degradation of the Q factor of a fundamental whispering-gallery mode of a microsphere resonator when a fiber tip is placed in the evanescent field of the mode. With a tip diameter of 80 nm it is possible to maintain a Q factor exceeding 10(8), even when the tip is as close as 10 nm to the sphere surface. This result demonstrates the possibility of using such a tip as a "nanotool" to actively place a single nanoparticle in a single high-Q mode with great precision to achieve well-controlled coupling. (C) 2002 Optical Society of America.
Contact
Nano-Optics Division Prof. Vahid Sandoghdar
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
