68 research outputs found
Sub-Doppler resonances in the back-scattered light from random porous media infused with Rb vapor
We report on the observation of sub-Doppler resonances on the back-scattered
light from a random porous glass medium with rubidium vapor filling its
interstices. The sub-Doppler spectral lines are the consequence of saturated
absorption where the incident laser beam saturates the atomic medium and the
back-scattered light probes it. Some specificities of the observed spectra
reflect the transient atomic evolution under confinement inside the pores.
Simplicity, robustness and potential miniaturization are appealing features of
this system as a spectroscopic reference.Comment: 6 pages, 4 figure
Magnetometer suitable for Earth field measurement based on transient atomic response
We describe the development of a simple atomic magnetometer using Rb
vapor suitable for Earth magnetic field monitoring. The magnetometer is based
on time-domain determination of the transient precession frequency of the
atomic alignment around the measured field. A sensitivity of 1.5 nT/
is demonstrated on the measurement of the Earth magnetic field in the
laboratory. We discuss the different parameters determining the magnetometer
precision and accuracy and predict a sensitivity of 30 pT/Comment: 6 pages, 5 figure
Polarization squeezing of light by single passage through an atomic vapor
We have studied relative-intensity fluctuations for a variable set of
orthogonal elliptic polarization components of a linearly polarized laser beam
traversing a resonant Rb vapor cell. Significant polarization squeezing
at the threshold level (-3dB) required for the implementation of several
continuous variables quantum protocols was observed. The extreme simplicity of
the setup, based on standard polarization components, makes it particularly
convenient for quantum information applications.Comment: Revised version. Minor changes. four pages, three figure
Theoretical study of dark resonances in micro-metric thin cells
We investigate theoretically dark resonance spectroscopy for a dilute atomic
vapor confined in a thin (micro-metric) cell. We identify the physical
parameters characterizing the spectra and study their influence. We focus on a
Hanle-type situation, with an optical irradiation under normal incidence and
resonant with the atomic transition. The dark resonance spectrum is predicted
to combine broad wings with a sharp maximum at line-center, that can be singled
out when detecting a derivative of the dark resonance spectrum. This narrow
signal derivative, shown to broaden only sub-linearly with the cell length, is
a signature of the contribution of atoms slow enough to fly between the cell
windows in a time as long as the characteristic ground state optical pumping
time. We suggest that this dark resonance spectroscopy in micro-metric thin
cells could be a suitable tool for probing the effective velocity distribution
in the thin cell arising from the atomic desorption processes, and notably to
identify the limiting factors affecting desorption under a grazing incidence.Comment: 12 pages, 11 figures theoretical articl
BiliLED low cost neonatal phototherapy, from prototype to industry
BiliLED is a phototherapy instrument designed to reduce bilirrubin blood rates in new born babies with jaundice. The light source is centred at 470 nm with a bandwidth of 35 nm and includes a matrix of 196 (14x14) InGaN LEDs. The optical elements are designed to maximize the light intensity useful for treatment, with a small number of LEDs in a compact and low cost unit. The optic array is such that every LED illuminates all the treatment area, which ensures redundancy and, thus, a high reliability not to be found in single-lamp instruments. Thermal dissipation and cost of BiliLED are both an order-of-magnitude smaller than conventional therapy lamps. BiliLED adjusts coetaneous irradiation with a feedback loop to compensate the loss or aging of LEDs achieving a calibrated light source for over a decade of use. A clinical trial in 20 hyperbilirrubinaemia patients shows 16% bilirrubin degradation within 24 hours of treatment, higher than most lamp phototherapy instruments. The steps from prototype to commercial model are described
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