50 research outputs found
Tapered optical fibers as tools for probing magneto-optical trap characteristics
We present a novel technique for measuring the characteristics of a
magneto-optical trap for cold atoms by monitoring the spontaneous emission from
trapped atoms coupled into the guided mode of a tapered optical nanofiber. We
show that the nanofiber is highly sensitive to very small numbers of atoms
close to its surface. The size and shape of the MOT, determined by translating
the cold atom cloud across the tapered fiber, is in excellent agreement with
measurements obtained using the conventional method of fluorescence imaging
using a CCD camera. The coupling of atomic fluorescence into the tapered fiber
also allows us to monitor the loading and lifetime of the trap. The results are
compared to those achieved by focusing the MOT fluorescence onto a photodiode
and it was seen that the tapered fiber gives slightly longer loading and
lifetime measurements due to the sensitivity of the fiber, even when very few
atoms are present.Comment: 21 pages, 5 figure
Optical nanofiber-based cavity induced by periodic air-nanohole arrays
We experimentally realized an optical nanofiber-based cavity by combining a
1-D photonic crystal and Bragg grating structures. The cavity morphology
comprises a periodic, triplex air-cube introduced at the waist of the
nanofiber. The cavity has been theoretically characterized using FDTD
simulations to obtain the reflection and transmission spectra. We have also
experimentally measured the transmission spectra and a Q-factor of ~784(87) for
a very short periodic structure has been observed. The structure provides
strong confinement of the cavity field and its potential for optical network
integration makes it an ideal candidate for use in nanophotonic and quantum
information systems
Chiral force of guided light on an atom
We calculate the force of a near-resonant guided light field of an ultrathin
optical fiber on a two-level atom. We show that, if the atomic dipole rotates
in the meridional plane, the magnitude of the force of the guided light depends
on the field propagation direction. The chirality of the force arises as a
consequence of the directional dependencies of the Rabi frequency of the guided
driving field and the spontaneous emission from the atom. This provides a
unique method for controlling atomic motion in the vicinity of an ultrathin
fiber.Comment: text and figures were revised, and a new discussion was adde
Trapping of a microsphere pendulum resonator in an optical potential
We propose a method to spatially confine or corral the movements of a
micropendulum via the optical forces produced by two simultaneously excited
optical modes of a photonic molecule comprising two microspherical cavities. We
discuss how the cavity enhanced optical force generated in the photonic
molecule can create an optomechanical potential of about 10 eV deep and 30 pm
wide, which can be used to trap the pendulum at any given equilibrium position
by a simple choice of laser frequencies. This result presents opportunities for
very precise all-optical self-alignment of microsystems.Comment: 13 pages, 3 figure
A simple, narrow, and robust atomic frequency reference at 993 nm exploiting the rubidium (Rb) to transition using one-color two-photon excitation
We experimentally demonstrate a one-color two-photon transition from the
ground state to the excited state in
rubidium (Rb) vapor using a continuous wave laser at 993 nm. The Rb vapor
contains both isotopes (Rb and Rb) in their natural abundances.
The electric dipole allowed transitions are characterized by varying the power
and polarization of the excitation laser. Since the optical setup is relatively
simple, and the energies of the allowed levels are impervious to stray magnetic
fields, this is an attractive choice for a frequency reference at 993 nm, with
possible applications in precision measurements and quantum information
processing.Comment: 8 pages, 4 figures, research articl