1,721,067 research outputs found
Efficient finite-element analysis of tilted open anisotropic optical channel waveguides
No full textAn iterative method to analyze open anisotropic dielectric waveguides with arbitrary dielectric tensor ε such as tilted channel waveguides is presented. The proposed β formulation approach reduces significantly the computational resources compared to previously proposed other choices
A Novel Approach to Raman Distributed Temperature-Sensing System for Short-Range Applications
Full text linkA novel approach to the development of Distributed Temperature-Sensing (DTS) systems based on Raman Scattering in Multimode optical fibers operating at around 800 nm is presented, focusing on applications requiring temperature profile measurement in the range of a few hundreds of meters. In contrast to the standard Raman DTS systems, which aim to shorten the pulse space width as much as possible to improve the precision of measurement, the novel approach studied in this work is based on the use of pulses with a space width that is approximately equal to the distance covered by the fiber under test. The proposed technique relies on numerical post-processing to obtain the temperature profile measurement with a precision of about +/- 3 degrees C and a spatial resolution of 8 m, due to the transaction phases of the optical pulses. This solution simplifies the electronic circuit development, also minimizing the required laser peak power needed compared to the typical narrow pulse techniques
Modal spectroscopy of multimode optical waveguides
No full textIn many integrated-optical devices operation is based on distributed coupling between two guided modes. Examples are directional couplers, travelling wave modulators and polarisation converters. In fabricating such devices it is a fundamental task to measure the propagation characteristics of these modes accurately enough for phase matching
Enlargement of the aortic annulus with glutaraldehyde-fixed bovine pericardium during aortic valve replacement
No full textNOVEL SURGICAL TECHNIQUE IN AORTIC VALVE REPLACEMEN
Experimental evaluation of real-time sigma-delta radio over fiber system for fronthaul applications
No full textSigma-delta radio over fiber (ςÎ-RoF) is an expedient technology for next-generation networks including 5G cloud/centralized radio access networks (C-RAN). In this article, we demonstrate a realistic experimental scenario for ςÎ-RoF link targeting C-RAN fronthaul applications, by using baseband second-order 1-bit sigma-delta modulation (ςÎ-M). The experimental set-up validates the LTE 20 MHz signals having modulation order of 256-quadrature amplitude modulation for a carrier frequency of 3 GHz, up to 10 km of standard single mode fiber. A detailed analysis of the ςÎ-RoF system performance is reported by adjacent channel leakage ratio and error vector magnitude. Furthermore, an experimental study is evaluated where ςÎ-RoF is compared with its counterparts. It is deduced that ςÎ-RoF corroborates the present range of C-RAN fronthaul networks and can be a promising candidate for future mobile haul applications
Reducing modal noise in short-range radio over multimode fibre links
No full textReducing gain fluctuations in Short Range Radio over Multimode Fiber Links requires Central Launch. Furthermore, the quality of today's optical connectors gives importance to the combined effect of finite detecting area and Laser frequency chirp. © 2010 Optical Society of America
Fiber-based Microwave Interferometer monitoring the Delay of Fiber-Optic Antenna Downlinks in Radioastronomic Scenarios
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