192,174 research outputs found
Depolarized guided acoustic wave Brillouin scattering in hollow-core photonic crystal fibers
By performing quantum-noise-limited optical heterodyne detection, we observe
polarization noise in light after propagation through a hollow-core photonic
crystal fiber (PCF). We compare the noise spectrum to the one of a standard
fiber and find an increase of noise even though the light is mainly transmitted
in air in a hollow-core PCF. Combined with our simulation of the acoustic
vibrational modes in the hollow-core PCF, we are offering an explanation for
the polarization noise with a variation of guided acoustic wave Brillouin
scattering (GAWBS). Here, instead of modulating the strain in the fiber core as
in a solid core fiber, the acoustic vibrations in hollow-core PCF influence the
effective refractive index by modulating the geometry of the photonic crystal
structure. This induces polarization noise in the light guided by the photonic
crystal structure.Comment: 8 pages, 5 figure
Ultra-large bandwidth hollow-core guiding in all-silica Bragg fibers with nano-supports
We demonstrate a new class of hollow-core Bragg fibers that are composed of
concentric cylindrical silica rings separated by nanoscale support bridges. We
theoretically predict and experimentally observe hollow-core confinement over
an octave frequency range. The bandwidth of bandgap guiding in this new class
of Bragg fibers exceeds that of other hollow-core fibers reported in the
literature. With only three rings of silica cladding layers, these Bragg fibers
achieve propagation loss of the order of 1 dB/m.Comment: 9 pages including 5 figure
Designing hollow nano gold golf balls.
Hollow/porous nanoparticles, including nanocarriers, nanoshells, and mesoporous materials have applications in catalysis, photonics, biosensing, and delivery of theranostic agents. Using a hierarchical template synthesis scheme, we have synthesized a nanocarrier mimicking a golf ball, consisting of (i) solid silica core with a pitted gold surface and (ii) a hollow/porous gold shell without silica. The template consisted of 100 nm polystyrene beads attached to a larger silica core. Selective gold plating of the core followed by removal of the polystyrene beads produced a golf ball-like nanostructure with 100 nm pits. Dissolution of the silica core produced a hollow/porous golf ball-like nanostructure
Hollow Core, Whispering Gallery Resonator Sensors
A review of hollow core whispering gallery resonators (WGRs)is given. After a
short introduction to the topic of whispering gallery resonators we provide a
description of whispering gallery modes in hollow or liquid core WGRs. Next,
whispering gallery mode (WGM) sensing mechanisms are outlined and some
fabrication methods for microbubbles, microcapillaries and other tubular WGM
devices are discussed. We then focus on the most common applications of hollow
core WGRs, namely refractive index and temperature sensing, gas sensing, force
sensing, biosensing, and lasing. The review highlights some of the key papers
in this field and gives the reader a general overview of the current
state-of-the-art
Anti-resonance, inhibited coupling and mode transition in depressed core fibers
The depressed core fiber (DCF), consisting of a low-index solid core, a high-index cladding and air surrounding, is in effect a bridge between the conventional step-index fiber and the tube-type hollow-core fiber from the point of view of the index profile. In this paper the dispersion diagram of a DCF is obtained by solving the full-vector eigenvalue equations and analyzed using the theory of anti-resonant and the inhibited coupling mechanisms. While light propagation in tube-type hollow-core fibers is commonly described by the symmetric planar waveguide model, here we propose an asymmetric planar waveguide for the DCFs in an anti-resonant reflecting optical waveguide (ARROW) model. It is found that the anti-resonant core modes in the DCFs have real effective indices, compared to the anti-resonant core modes with complex effective indices in the tube-type hollow-core fibers. The anti-resonant core modes in the DCFs exhibit similar qualitative and quantitative behavior as the core modes in the conventional step-index fibers. The full-vector analytical results for the simple-structure DCFs can contribute to a better understanding of the anti-resonant and inhibited coupling guidance mechanisms in other complex inversed index fibers
A one-dimensional ultracold medium of extreme optical depth
We report on the preparation of a one-dimensional ultracold medium in a
hollow-core photonic crystal fiber, reaching an effective optical depth of
1000(150). We achieved this extreme optical depth by transferring atoms from a
magneto-optical trap into a far-detuned optical dipole trap inside the
hollow-core fiber, yielding up to 2.5(3)10 atoms inside the core
with a loading efficiency of . The preparation of an ultracold
medium of such huge optical depth paves the way towards new applications in
quantum optics and nonlinear optics
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