82,826 research outputs found
The Photonic Lantern
Photonic lanterns are made by adiabatically merging several single-mode cores
into one multimode core. They provide low-loss interfaces between single-mode
and multimode systems where the precise optical mapping between cores and
individual modes is unimportant.Comment: 45 pages; article unchanged, accepted for publication in Advances in
Optics and Photonic
Improved light extraction in the bioluminescent lantern of a Photuris firefly (Lampyridae)
A common problem of light sources emitting from an homogeneous
high-refractive index medium into air is the loss of photons by total internal
reflection. Bioluminescent organisms, as well as artificial devices, have to
face this problem. It is expected that life, with its mechanisms for evolution,
would have selected appropriate optical structures to get around this problem,
at least partially. The morphology of the lantern of a specific firefly in the
genus Photuris has been examined. The optical properties of the different parts
of this lantern have been modeled, in order to determine their positive or
adverse effect with regard to the global light extraction. We conclude that the
most efficient pieces of the lantern structure are the misfit of the external
scales (which produce abrupt roughness in air) and the lowering of the
refractive index at the level of the cluster of photocytes, where the
bioluminescent production takes place.Comment: 13 pages, 11 figures, published in Optics Expres
Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application
Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r(sub 0)=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array
ORANGE You Interested In Pumpkins...., 2009
The most popular use of pumpkins may be for jack-o-lanterns and fall decorations but they have many more uses. When selecting a pumpkin for cooking, the best selection is a “pie pumpkin” or “sweet pumpkin.” These are smaller than the large jack-o-lantern pumpkins and the flesh is sweeter and less watery. You can substitute the jack-o-lantern variety with fairly good results. Pumpkin seeds can be used in tossed salads, casseroles, soups, and other baked goods, either ground or whole. Although roasted pumpkin seeds tend to be better-tasting, you'll receive higher nutritional value from the raw seeds. So decorate your place with a pumpkin and make something. This brochure produced by The Department of Agriculture and Land Stewardship
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