IMPACT OF FLUCTUATIONS OF GRADED-INDEX OPTICAL FIBER PARAMETERS ON PROPAGATION OF GAUSSIAN BEAMS

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Hassan Pakarzadeh ◽  
Jamshid Dousti
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Optical Communications ◽  
Spot Size ◽  
Gaussian Beams ◽  
Beam Spot ◽  
Optical Signals ◽  
Graded Index ◽  
Beam Spot Size ◽  
The Impact

In this paper, the impact of fluctuations of graded-index (GRIN) optical fiber parameters on propagation of Gaussian beams is investigated by using ABCD matrix approach and a stochastic process. Since GRIN optical fibers have many applications in the optical communications, variations of fiber parameters such as core refractive index, core-cladding index difference and core radius affect the propagation of optical signals. Results show that the variations of the mentioned parameters change the beam spot size as well as the periodicity of the beam. Also, the fluctuations of such fiber parameters increase the spot size of the output Gaussian beam in comparison with the case when the fluctuations are ignored.   

PLANAR JOSEPHSON JUNCTIONS FABRICATED BY FOCUSED-ION BEAM

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3359-3360 ◽  
Author(s):  
Hye-Won Seo ◽  
Quark Y. Chen ◽  
Chong Wang ◽  
Wei-Kan Chu ◽  
T. M. Chuang ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Josephson Junctions ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Spot Size ◽  
Physical Significance ◽  
Fabrication Technique ◽  
Beam Spot ◽  
Beam Spot Size ◽  
Current Voltage

We have fabricated nano-scaled planar superconductor-insulator-superconductor Josephson junctions using focused ion beam (FIB) with beam spot size ~5 nm . To study the effectiveness of this fabrication technique and for the purpose of comparisons, a variety of samples have been made based on high temperature superconducting (HTS) YBa2Cu3O7-δ electrodes. The insulators are either vacuum or silicon dioxide. The samples showed current-voltage (IV) characteristics typical of a resistively shunted junction (RSJ). We will discuss various aspects of the processing methods and the physical significance of the junction characteristics.

scholarly journals Damage detection in laminar thermoplastic composite materials by means of embedded optical fibers

2006 ◽  
Vol 60 (7-8) ◽  
pp. 176-179
Author(s):  
Aleksandar Kojovic ◽  
Irena Zivkovic ◽  
Ljiljana Brajovic ◽  
Dragan Mitrakovic ◽  
Radoslav Aleksic
Keyword(s):  
Composite Materials ◽  
Optical Fiber ◽  
Real Time ◽  
Optical Fibers ◽  
Impact Damage ◽  
Experimental Testing ◽  
Low Energy ◽  
Thermoplastic Composite ◽  
Woven Fabric ◽  
The Impact

This paper investigates the possibility of applying optical fibers as sensors for investigating low energy impact damage in laminar thermoplastic composite materials, in real time. Impact toughness testing by a Charpy impact pendulum with different loads was conducted in order to determine the method for comparative measurement of the resulting damage in the material. For that purpose intensity-based optical fibers were built in to specimens of composite materials with Kevlar 129 (the DuPont registered trade-mark for poly(p-phenylene terephthalamide)) woven fabric as reinforcement and thermoplastic PVB (poly(vinyl butyral)) as the matrix. In some specimens part of the layers of Kevlar was replaced with metal mesh (50% or 33% of the layers). Experimental testing was conducted in order to observe and analyze the response of the material under multiple low-energy impacts. Light from the light-emitting diode (LED) was launched to the embedded optical fiber and was propagated to the phototransistor-based photo detector. During each impact, the signal level, which is proportional to the light intensity in the optical fiber, drops and then slowly recovers. The obtained signals were analyzed to determine the appropriate method for real time damage monitoring. The major part of the damage occurs during impact. The damage reflects as a local, temporary release of strain in the optical fiber and an increase of the signal level. The obtained results show that intensity-based optical fibers could be used for measuring the damage in laminar thermoplastic composite materials. The acquired optical fiber signals depend on the type of material, but the same set of rules (relatively different, depending on the type of material) could be specified. Using real time measurement of the signal during impact and appropriate analysis enables quantitative evaluation of the impact damage in the material. Existing methods in most cases use just the intensity of the signal before and after the impact, as the measure of damage. This method could be used to monitor the damage in real time, giving warnings before fatal damage occurs.

Study on Coupling of Step and Graded Index Single Mode Optical Fiber Considering the Transverse Misalignment

2020 ◽  
Vol 8 (2) ◽  
pp. 78-82
Author(s):  
Prosenjit Roy Chowdhury ◽  
◽  
Keyword(s):  
Optical Fiber ◽  
Communication Systems ◽  
Structural Parameters ◽  
Fractional Power ◽  
Single Mode ◽  
Spot Size ◽  
Fiber Coupling ◽  
Fundamental Parameters ◽  
Graded Index ◽  
Wide Range

"Advance design and day to day up-gradation of communication system is the requirement of international telecommunication. The optical communication systems involve the effective fiber coupling or splicing to meet the need of long communication channel. When the studies on both the intensive and extensive properties of optical fiber are exploring new research horizons, the effectiveness of such systems can be calibrated with transmission parameters like transmitted fractional power, which is a function of ‘spot size’ as well. Our study of fiber junctions based on fundamental parameters like wavelength, fiber profile index etc. has touched some unrevealed areas and explored some interesting results. The profile index of optical fiber has received less attention compared to other structural parameters of optical fiber but our study at important wavelengths for different profiles has shown that the less-used fiber profiles has some interesting premier outcomes, which can introduce some significant impact on optical fiber based system design and engineering. We have observed almost frequency or wavelength independent transmitted fractional power around the most used 1.55 micrometer wavelengths at some rarely used fiber profile index. Our study predicts the best and worst fiber profiles for transmitted fractional power (T ), at the same time, we have observed the fiber profile index independent region for a band of ‘T’ values. The reporting and its approach are found to be premier in this field. So, our work is reporting a comparison of effective fiber-to-fiber coupling, based on fiber profile index of different fibers. It is also giving a clear view of the wavelength dependency of effective fiber coupling for different fibers having wide range of graded fiber profiles."

Development of a high-current microbeam system

2014 ◽  
Vol 24 (03n04) ◽  
pp. 101-110 ◽  
Author(s):  
S. Matsuyama ◽  
K. Ishii ◽  
S. Suzuki ◽  
A. Terakawa ◽  
M. Fujiwara ◽  
...  
Keyword(s):  
Quadrupole Doublet ◽  
Spot Size ◽  
Beam Current ◽  
Chemical State ◽  
High Current ◽  
Rigid Support ◽  
Beam Spot ◽  
X Ray ◽  
Beam Spot Size

We report on the development of a high-current microbeam system for wavelength-dispersive X-ray micro particle-induced X-ray emission (WDX-[Formula: see text]-PIXE) for chemical state mapping. The microbeam system is composed of two slits and a quadrupole doublet lens mounted on a heavy rigid support. The microbeam system is installed immediately after a switching magnet. A beam brightness of [Formula: see text] is obtained at a half-divergence of 0.1 mrad. A beam current of more than 300 pA is obtained for object sizes of [Formula: see text] with a half-divergence of 0.2 mrad, which corresponds to a beam spot size of [Formula: see text]. The calculated spot size of the beam was [Formula: see text] and the measured spot size was [Formula: see text]. The WDX-[Formula: see text]-PIXE system with the microbeam system is now operational.

Push beam spot-size dependence of atom transfer in a double magneto-optical trap setup

2013 ◽  
Vol 84 (7) ◽  
pp. 073102 ◽  
Author(s):  
S. P. Ram ◽  
S. K. Tiwari ◽  
S. R. Mishra ◽  
H. S. Rawat
Keyword(s):  
Size Dependence ◽  
Optical Trap ◽  
Spot Size ◽  
Atom Transfer ◽  
Magneto Optical Trap ◽  
Beam Spot ◽  
Beam Spot Size

Defect Sizing in Pipeline Welds: What Can We Really Achieve?

2004 ◽  
Author(s):  
Michael Moles
Keyword(s):  
Fracture Mechanics ◽  
Time Of Flight ◽  
Spot Size ◽  
Height Measurement ◽  
Beam Spot ◽  
Analysis Techniques ◽  
Time Of Flight Diffraction ◽  
Beam Spot Size ◽  
Weld Inspection ◽  
Focused Transducers

Pipelines are now using Fitness-For-Service (FFS) for accept/reject of weld defects. FFS requires accurate measurement of defect height for Fracture Mechanics assessments. The standard pipeline weld inspection technique of radiography is incapable of such measurements. However, the newer technique of ultrasonics can measure defect height, in principle. Initially ultrasonic amplitude methods were used for height measurement, but these proved unreliable. Now diffraction methods, especially Time-Of-Flight-Diffraction (TOFD), are being used in conjunction. This paper reviews previous work — mainly large nuclear studies like PISC II — and published pipeline sizing studies. The best nuclear sizing was within a few millimetres, using diffraction. In contrast to nuclear, pipeline AUT uses zone discrimination, focused transducers, much thinner material and simpler analysis techniques. Current accuracies are typically ± 1 mm (terminology undefined), which correlates with the beam spot size and typical weld pass. Requests for accuracies of ± 0.3 mm are probably unachievable, though future R&D should significantly improve pipeline sizing.

SU-F-T-167: Measurement of Proton Beam Spot Size Using a 2D Ion Chamber Array for Daily QA

2016 ◽  
Vol 43 (6Part15) ◽  
pp. 3500-3500
Author(s):  
N Thorne ◽  
A Kassaee
Keyword(s):  
Proton Beam ◽  
Spot Size ◽  
Beam Spot ◽  
Ion Chamber ◽  
Beam Spot Size

Lensed Plastic Optical Fiber with a Convexo-Concave Fiber Endface for Coupling Laser Diodes With Plastic Optical Fiber

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Yih-Tun Tseng ◽  
Shu-Ming Chang ◽  
Sheng-He Huang ◽  
Wood-Hi Cheng
Keyword(s):  
Optical Fiber ◽  
Light Source ◽  
Optical Fibers ◽  
Transmission Rate ◽  
Coupling Efficiency ◽  
Small Diameter ◽  
Plastic Optical Fiber ◽  
Graded Index ◽  
Coupling Laser ◽  
Working Distance

This work presents a novel lensed plastic optical fiber (POF), efficiently coupled with a light source. A convexo-concave plastic lens (CCPL) was bound to a flat-end plastic optical fiber using laser transmission welding (LTW) to form a convexo-concave-shaped fiber endface (CCSFE). The novel lensed plastic optical fiber has a longer working distance and a higher coupling efficiency than conventional lensed plastic optical fibers. 850 nm fiber is often used in high-power 2.5 Gb/s transmission rate. Experimental POF is perfluorinated POF, 62.5–500 μm diameter, 850∼1300 μm wavelength, 10 dB/km power loss rate, 2.5 Gb/s transmission rate. Because of the small diameter of POF, it is difficult to couple between the light source and POF. Therefore, it is important to develop a lensed fiber structure to increase the coupling efficiency. Experiments indicate that the coupling efficiency between a laser diode at a wavelength of 850 nm and a graded-index POF is as high as 85% with a long working distance of 250 μm. The measured tolerance, in relation to the lateral and vertical displacements and tilt, are satisfactory for practical active alignment.

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