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"Optical wave guides Computer simulation."
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Algorithms and Simulation Analysis of Optical Waveguide Devices to Generate Supercontinuum
With the development of the times, our life is becoming more and more intelligent. In this regard, we have also made great progress in the field of communication intelligence. But we still need optical wavelength devices to generate ultra-continuous spectromets that can be used in the field of communications. In this regard, the purpose of this paper is to study the optical wave guide device to generate ultra-continuous spectrum algorithm, and its simulation and analysis. The experiment in this paper begins after careful consideration of the security of user data and some trade secrets, and on the premise of experimental security, the accuracy of the algorithm is measured and simulated by using sandbox simulation based on computer technology. The experimental results show that the algorithm can increase the speed of ultra-continuous spectrum of optical wave guide device by about 50%. And in the simulation simulation application, the stability is good.
Journal Article
Sideband-suppressed narrow bandpass fibre Fabry-Pérot filter composed of fibre Bragg grating and dielectric mirror
To suppress the undesirable sideband transmission occurring in the conventional fibre Bragg grating based Fabry-Pérot filter, a fibre Fabry-Pérot interferometer that is composed of a single fibre Bragg grating and a broadband high-reflectance dielectric mirror coated on a fibre end surface is considered and its very narrow transmission bandwidth of 8.8 pm and high sideband suppression ratio of more than 20 is experimentally demonstrated in good conformity with the numerical simulation.
Journal Article
60 GHz grounded-coplanar-waveguide-to-substrate-integrated-waveguide transition for RoF transmitters
A novel transition from a grounded-coplanar waveguide to a substrate integrated-waveguide (SIW) is presented featuring a fully planar bias tee for the development of 60 GHz radio-over-fibre photonic transmitters for indoor applications. The transition is intended to serve as a connection between a 60 GHz photodiode chip and SIW antennas suitable for indoor data distribution. Simulations show that in the whole 57–64 GHz communication band, the return loss (RL) is at least 15 dB, whereas the insertion loss (IL), is < 0.9 dB. Measurements of a back-to-back configuration confirm the numerical results, with a IL of ∼2 dB and a RL > 12 dB.
Journal Article
Simulation of dye solar cells: through and beyond one dimension
In this work we present a Computer Aided Design (CAD) software, called TiberCAD, to simulate Dye Sensitized Solar Cells (DSC). DSCs are particularly interesting devices due to their high efficiency (more than 11% on small area and 8% on large area) and long stability. Since their first development, much progress has been made in terms of efficiency, stability, lifespan and engineering of the device. However, the field of DSCs still lacks a complete model able to simulate the entire device over a general domain including all its components. In our model a drift-diffusion set of equations for the different charge carriers coupled to Poisson equation has been implemented within finite element method. The model takes into account also trap assisted transport for electrons in the mesoporous titanium dioxide with a phenomenological model derived from multi-trapping model.
Three different applications of the code in 1, 2 and 3D are presented. The first 1D simulation is a study of correlation between physical parameters of the cell and energy conversion efficiency. A second application, 2D, discusses the effect on density and current distributions for different contacting of the cell and loss induced by the shadowing of metallic fingers. Finally, the third case, 3D, presents two different and innovative topologies for a DSC. A cell where contacts and illumination surface are completely decoupled and a DSC wrapped around an optical fiber.
Journal Article
Image Improvement from a Sodium-Layer Laser Guide Star Adaptive Optics System
A sodium-layer laser guide star beacon with high-order adaptive optics at Lick Observatory (Mount Hamilton, California) produced a factor of 2.4 intensity increase and a factor of 2 decrease in full width at half maximum for an astronomical point source, compared with image motion compensation alone. The image full widths at half maximum were identical for laser and natural guide stars (0.3 arc second). The Strehl ratio with the laser guide star was 65 percent of that with a natural guide star. This technique should allow ground-based telescopes to attain the diffraction limit, by correcting for atmospheric distortions.
Journal Article
New high fill-factor triangular microlens array fabrication method using UV proximity printing
A simple and effective method for fabricating a high fill-factor triangular microlens array using the proximity printing in lithography process is reported. The technology utilizes the UV proximity printing by controlling the printing gap between the mask and substrate. The designed approximate triangle microlens array pattern can be fabricated in photoresist. This is because to the UV light diffraction deflects away from the aperture edges and produces a certain exposure in photoresist material outside the aperture edges. This method can precisely control the geometric profile of a high fill-factor triangular microlens array. The experimental results showed that the triangular photoresist microlens array could be formed automatically when the printing gap ranged from 240 to 840 μm. The gapless triangular microlens array will be used to increase the luminance for the backlight module of liquid crystal displays.
Journal Article
Simulation of the flow in a coating applicator for optical fiber manufacture
A detailed numerical study is carried out on the flow field generated in an open-cup coating applicator during the coating process in the manufacture of optical fibers. This is a critical problem in the manufacture of optical fibers and poses several challenges to numerical modeling. A finite volume numerical model, using multiple domains to represent the fluid chamber and the die, is employed to obtain results on the flow. A coordinate transformation is used to model the complex geometry of the flow region. Fairly generic configurations are considered and a wide range of fiber drawing speeds, ranging up to 15 m/s, is investigated. Different boundary conditions, such as free and solid surface, at the entrance of the moving fiber are considered. Several coating materials are simulated, along with wide ranges of operating conditions and geometric designs. Though different temperatures are considered for the coating material, to obtain different fluid viscosities, the flow is considered to be isothermal. The focus is on the flow pattern and on the velocity fields in the fluid chamber and the die. Also, of interest are the resulting mass flow rate, which yields the final coating thickness, and the effects of the inlet conditions. The characteristics of the recirculating flow that arises in many cases are investigated in detail. The results are presented in terms of streamlines, velocity distributions and flow rates. The effects of geometry, coating material and die shape are investigated in detail. This is the first part of an on-going detailed study on the simulation of coating applicators for the manufacture of optical fibers in order to improve uniformity, consistency, and quality of the coating.
Journal Article
Kinematics of fibre optics sensory systems for control of a natural gas engine
Abstract
A fibre optics combustion intensity detection sensor is developed for the purpose of monitoring and controlling natural gas engines. The sensory system, which is based on the detection of the intensity of the combustion event, is mounted on the top of the engine block. Prior to implementation of the detection system, the accurate kinematics of the sensor probe within the combustion chamber needs to be identified while taking account of the geometric complexity of the engine design. This requires the understanding of the kinematics of probe position within the spatial relations of the engine block geometry that is likely to give a good coverage of the combustion processes. This paper therefore presents a new model that was implemented on natural gas engines but could also be used for identifying the appropriate location within the combustion chamber of any modern engine. An application example using the model is presented. The model provides the ability to monitor completely the stages of combustion within the cycle-to-cycle operation of the engine and use the signal thereof for management and control of the engine. Experience gained from the application of the model resulted in the development of the probe deployment rule discussed in this paper.
Journal Article
Design of the wavefront sensor unit of ARGOS, the LBT laser guide star system
ARGOS is the laser guide star ground layer adaptive optics system of the LBT. ARGOS is designed to bring a moderate but uniform reduction of the PSF size over a FoV as large as 4x4arcmin, allowing a significative increase of the science throughput of LUCI, the LBT NIR imager and MOS. ARGOS relays on 3 Rayleigh beacons to sense the lower layers of the atmosphere achieving almost 100% sky coverage. The ground layer AO correction is allowed by the 2 adaptive secondaries of the LBT. This PhD thesis first discusses a study based on numerical simulations and aimed to evaluate the performance of ARGOS. This work has been carried out using CAOS and representing in the code most of the features that characterize the system itself: as the laser beacon propagation in the atmosphere, the SH type wavefront sensing, the AO reconstruction and closed loop delays and the atmosphere tip-tilt sensing done using a NGS and a quad-cell type sensor. The results obtained in this study are in agreement and definitively confirm the performance evaluated in the phase studies of the project. This study shows that ARGOS is able to produce a reduction of a factor 2 of the seeing bringing to a gain of a factor 4 in the integration time required by LUCI. This PhD thesis reports also the optical design and optimization of both the ARGOS dichroic window, used to separate the laser light from the science light, and the LGS WFS, that evaluates the ground layer aberrations averaging the SH measurements in the direction of the 3 LGS. For both of the subsystems the optimization process is analyzed. Then are evaluated the tolerances and specifications for the production and coating of the optics. Finally are evaluated the stability requirement for the mechanical design and the degrees of freedom needed for the alignment purposes.
Paper