We report on the realization of a whispering-gallery-mode laser based on neodymium-doped silica microspheres. Absorbed pump powers at threshold are as low as 200 nW. The linear variation of the threshold with the loss factor of the cavity mode has also been observed. We discuss the potential of this system as a permanent microlaser operating with a few active ions at liquid-helium temperature.
Characterizing whispering-gallery modes in microspheres by direct observation of the optical standing-wave pattern in the near field
J.C. Knight,
N. Dubreuil,
Vahid Sandoghdar,
J. Hare,
V. LefevreSeguin,
J.M. Raimond,
S. Haroche
We demonstrated the use of a near-field probe to map the evanescent field of an optical standing wave in a fused-silica whispering-gallery mode microresonator. The periodicity of the observed standing wave allows us to estimate accurately the radial mode number of the whispering-gallery mode resonance that is being excited. We find that the use of a fiber half-coupler to excite these resonances in fused-silica microspheres results in only the lowest radial mode numbers' being strongly excited, as predicted. (C) 1996 Optical Society of America
Spectroscopy of atoms confined to the single node of a standing wave in a parallel-plate cavity
Vahid Sandoghdar,
C.I. Sukenik,
S. Haroche,
E.A. Hinds
have performed spectroscopy on sodium atoms that are optically channeled in the single node of a laser standing wave set up across a parallel-plate cavity. Using this technique we have extended our previous measurement of the Lennard-Jones van der Waals energy-level shift [Sandoghdar et al., Phys. Rev. Lett. 68, 3432 (1992)] down to a cavity width of similar to 500 nm. We discuss the applications of this technique to the precise measurement of atom-surface distances.
Contact
Nano-Optics Division Prof. Vahid Sandoghdar
Max Planck Institute for the Science of Light Staudtstr. 2 91058 Erlangen, Germany
