68 research outputs found
Surfaces roughness effects on the transmission of Gaussian beams by anisotropic parallel plates
Influence of the plate surfaces roughness in precise ellipsometry experiments
is studied. The realistic case of a Gaussian laser beam crossing a uniaxial
platelet is considered. Expression for the transmittance is determined using
the first order perturbation theory. In this frame, it is shown that
interference takes place between the specular transmitted beam and the
scattered field. This effect is due to the angular distribution of the Gaussian
beam and is of first order in the roughness over wavelength ratio. As an
application, a numerical simulation of the effects of quartz roughness surfaces
at normal incidence is provided. The interference term is found to be strongly
connected to the random nature of the surface roughness.Comment: 18 pages, Journal of Physics D: Applied Physics, volume 36, issue 21,
pages 2697 - 270
All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators
We review our recent work on tunable, ultrahigh quality factor
whispering-gallery-mode bottle microresonators and highlight their applications
in nonlinear optics and in quantum optics experiments. Our resonators combine
ultra-high quality factors of up to Q = 3.6 \times 10^8, a small mode volume,
and near-lossless fiber coupling, with a simple and customizable mode structure
enabling full tunability. We study, theoretically and experimentally, nonlinear
all-optical switching via the Kerr effect when the resonator is operated in an
add-drop configuration. This allows us to optically route a single-wavelength
cw optical signal between two fiber ports with high efficiency. Finally, we
report on progress towards strong coupling of single rubidium atoms to an
ultra-high Q mode of an actively stabilized bottle microresonator.Comment: 20 pages, 24 figures. Accepted for publication in Applied Physics B.
Changes according to referee suggestions: minor corrections to some figures
and captions, clarification of some points in the text, added references,
added new paragraph with results on atom-resonator interactio
Designing touch-enabled electronic flight bags in SAR helicopter operations
In order to benefit from potential reduced operational costs and crew workload airlines are increasingly interested in touchscreen-based Electronic Flight Bags (EFB). This paper focuses on the specific domain of Search and Rescue (SAR) Helicopters. A first set of results aiming to explore and understand potential benefits and challenges of an EFB in a SAR environment will be presented. A review of related work, operational observations and interviews with pilots were conducted to understand and specify the use context. Digital Human Modelling (DHM) software was used to determine physical constraints of an EFB in this type of flight deck. A scenario was developed which will be used in future to define features, content and functionality that a SAR pilot may wish to see in an EFB. Developed initial interface design guidelines are presented
Cavity-enhanced direct frequency comb spectroscopy
Cavity-enhanced direct frequency comb spectroscopy combines broad spectral
bandwidth, high spectral resolution, precise frequency calibration, and
ultrahigh detection sensitivity, all in one experimental platform based on an
optical frequency comb interacting with a high-finesse optical cavity. Precise
control of the optical frequency comb allows highly efficient, coherent
coupling of individual comb components with corresponding resonant modes of the
high-finesse cavity. The long cavity lifetime dramatically enhances the
effective interaction between the light field and intracavity matter,
increasing the sensitivity for measurement of optical losses by a factor that
is on the order of the cavity finesse. The use of low-dispersion mirrors
permits almost the entire spectral bandwidth of the frequency comb to be
employed for detection, covering a range of ~10% of the actual optical
frequency. The light transmitted from the cavity is spectrally resolved to
provide a multitude of detection channels with spectral resolutions ranging
from a several gigahertz to hundreds of kilohertz. In this review we will
discuss the principle of cavity-enhanced direct frequency comb spectroscopy and
the various implementations of such systems. In particular, we discuss several
types of UV, optical, and IR frequency comb sources and optical cavity designs
that can be used for specific spectroscopic applications. We present several
cavity-comb coupling methods to take advantage of the broad spectral bandwidth
and narrow spectral components of a frequency comb. Finally, we present a
series of experimental measurements on trace gas detections, human breath
analysis, and characterization of cold molecular beams.Comment: 36 pages, 27 figure
Targeted enzyme prodrug therapy for metastatic prostate cancer – a comparative study of L-methioninase, purine nucleoside phosphorylase, and cytosine deaminase
op. 1. Chansons de poĂŞtes
Comprend : Vieille chanson du jeune temps ; La jeune morte ; La musique ; La mort des amants ; Désespoir ; La chanson du cœur ; La valse ; Ariette ; Ah ! le bruit affreux de la vie ! ; Toi par qui j'ai senti pour des heures trop brèves ; Musique sur l'eau ; Colloque sentimental ; Ce cœur plaintif ; Quand je viendrai m'asseoir dans le vent ; Belle, vivant tes jours filés par le desti
Les êtres merveilleux au XVIIIe siècle entre apparition et manifestation : une forme d’empirisme littéraire ?
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