Search results for "HIF"

DFT calculations of structures, 13C NMR chemical shifts and Raman RBM mode of simple models of ultra small diameter (4,0) zigzag hydroxylated single …

2012

Abstract Selected acenes, cyclic acenes and model zigzag (4,0) single wall carbon nanotubes (SWCNTs) with one hydroxylic group at the open end were fully optimized at the B3LYP/6-31G* level of theory. The impact of molecule size on the B3LYP/pcS-2 calculated 13 C NMR chemical shifts was studied to characterize pristine and tip-monofunctionalized ultra narrow SWCNTs. The harmonic frequency of Raman radial breathing mode (RBM) was determined for monohydroxylated cyclic acenes and correlated with their diameter. A regular convergence of selected CC bond lengths, RBM frequency and carbon chemical shifts upon increasing the size of the systems was observed and fitted toward very large systems wi…

In-fiber time-resolved acousto-optics

2014

Time-resolved in-fiber acousto-optics permit the measurement of sub-ppm perturbations of the modal dispersion curves along sections of fiber exceeding 1 m long, with a spatial resolution in the order of few cm.

Dispersion induced effects of high-order optical sidebands in the performance of millimeter-wave fiber-optic links

2006

In this paper, chirped fiber Bragg gratings (CFBGs) are proposed as signal-phase controllers for microwave-photonic wireless downstream fiber links. The effect of high-order modulation optical sidebands that disturbs the output mm-wave signal due to the chromatic dispersion induced by the gratings is studied theoretically and experimentally. The 1st and 2nd mm-wave harmonics of the output signal have been measured for conventional intensity modulation and for intensity modulation with optical carrier suppression. In the last case, data transmission at 2.5 Gb/s is demonstrated through a chirped grating of 280 ps/nm dispersion in a 40-GHz modulated link.

Extremely efficient evaluation of chromatic dispersion in realistic photonic crystal fibers

2004

We present a fast and accurate procedure for the evaluation of chromatic dispersion in photonic crystal fibers. It combines an iterative Fourier technique to compute the propagation constant at any fixed wavelength and an analytical approach to calculate its derivatives.

Suppression of pulse pedestal using nonlinear optical loop mirrors in grating-compensated dispersion-managed fiber transmission systems

2006

Pulse pedestal suppression by nonlinear optical loop mirrors is utilized to reduce the intersymbol interference caused by the group delay ripples of a real grating profile in dispersion-managed communication systems compensated by chirped fiber gratings.

Muon Knight-shift measurements in CeSn3and some isostructural rare-earth compounds

1984

Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons

2013

[EN] Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons. The networks are produced through self-assembly resulting from the molecular conformation and noncovalent intermo…

Time-domain fiber laser hydrogen sensor.

2004

We report a novel scheme for a fiber-optic hydrogen sensor based on an erbium-doped fiber laser with a palladium-coated tapered fiber within the laser cavity. The tapered fiber acts as a hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases, changing the cavity losses and leading to a modification of the laser transient. The hydrogen concentration is obtained by simple measurement of the buildup time of the laser. This technique translates the measurement of hydrogen concentration into the time domain, and it can be extended to many intensity-based fiber sensors. Relative variations in the buildup time of up to 55% at an increase o…

Intensity-Modulated Optical Fiber Sensor for AC Magnetic Field Detection

2015

An erbium-doped (Er3+) fiber optic laser is proposed for sensing alternated magnetic fields by measuring the laser intensity modulation. The sensor is fabricated using two partially overlapped narrow-band fiber Bragg gratings (FBGs) and a section of doped fiber in a Fabry–Perot configuration. Laser power stability and bandwidth are studied while changing the overlap. A bulk rod of TbDyFe, a magnetostrictive material, is glued to both the FBGs and the laser wavelength and power are modulated according to the magnetic field. Acquisition and processing are done using virtual instrumentation. Results have shown the possibility of detecting 11.18 $\mu \text{T}_{\mathrm {{rms}}}/\surd $ Hz for an…

Ultrahigh-birefringent squeezed lattice photonic crystal fiber with rotated elliptical air holes.

2010

We report an experimental realization of a highly birefringent photonic crystal fiber as a result of compressing a regular hexagonal structure. The experimental measurements estimate a group birefringence of approximately 5.5x10(-3) at 1550 nm in good agreement with the numerical results. We study the influence of compressing the regular structure at different directions and magnifications, obtaining a method to realistically enhance the phase birefringence while moderating the group birefringence.