scholarly journals Fabrication of Silica Optical Fibers: Optimal Control Problem Solution

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 77
Author(s):  
Vladimir Pervadchuk ◽  
Daria Vladimirova ◽  
Irina Gordeeva ◽  
Alex G. Kuchumov ◽  
Dmitrij Dektyarev
Keyword(s):  
Optimal Control ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Chemical Vapor ◽  
Geometric Optimization ◽  
Hydrogen Gas ◽  
Problem Solution ◽  
Control Functions ◽  
Optical Fiber Drawing ◽  
Optimality Systems

In this work, a new approach to solving problems of optimal control of manufacture procedures for the production of silica optical fiber are proposed. The procedure of silica tubes alloying by the Modified Chemical Vapor Deposition (MCVD) method and optical fiber drawing from a preform are considered. The problems of optimal control are presented as problems of controlling distributed systems with objective functionals and controls of different types. Two problems are formulated and solved. The first of them is the problem of the temperature field optimizing in the silica tubes alloying process in controlling the consumption of the oxygen–hydrogen gas mixture (in the one- and two-dimensional statements), the second problem is the geometric optimization of fiber shape in controlling the drawing velocity of the finished fiber. In both problems, while using an analog to the method of Lagrange, the optimality systems in the form of differential problems in partial derivatives are obtained, as well as formulas for finding the optimal control functions in an explicit form. To acquire optimality systems, the qualities of lower semicontinuity, convexity, and objective functional coercivity are applied. The numerical realization of the obtained systems is conducted by using Comsol Multiphysics.

Optical Fiber Hydrogen Sensor Based on Magnetron Sputtered Pd/V2O5 Films

2010 ◽  
Vol 663-665 ◽  
pp. 898-901
Author(s):  
Ling De Zhou ◽  
Jin Shan Huang ◽  
Yong Shi ◽  
Yin Wei Wu ◽  
Hai Hu Yu
Keyword(s):  
Thin Films ◽  
Optical Fiber ◽  
Response Time ◽  
Optical Fibers ◽  
Hydrogen Sensor ◽  
Hydrogen Gas ◽  
Multimode Fibers ◽  
Glass Substrates ◽  
Reflected Light ◽  
20 Nm

Laminated thin films composed of V2O5 and Pd (or Pt-Pd) layers were deposited on glass substrates and the end faces of multimode optical fibers, and the sensitive behaviors of the thin films to hydrogen gas were studied using a UV-visible spectrophotometer and an optical fiber sensor’s experimental setup. Both the thickness of the V2O5 layer and that of the Pd layer have obvious influences on the sensitivity performance of the Pd/V2O5 films. The Pd (30 nm)/V2O5 (280 nm) film deposited on a glass substrate is sensitive to 0.1% hydrogen and the highest change in relative transmittance is about 25% when exposed to 4% hydrogen. Pd/V2O5 films were coated onto the end faces of multimode fibers to form optical fiber sensors. The response time of the Pd (20 nm)/V2O5 (280 nm) sensor is about 50 s and the change in relative reflected light intensity is about 18% upon exposure to 4% hydrogen. Deposition of Pt-Pd double layer instead of Pd signal layer over V2O5 can reduce the response time of the sensor. The response time of the Pd (20 nm)/V2O5 (280 nm) sensor is about 50 s, while that of the Pt (10 nm)-Pd (10 nm)/V2O5 (280 nm) sensor is about 25 s.

Numerical Simulation of Transport in Optical Fiber Drawing With Core-Cladding Structure

2004 ◽  
Author(s):  
Chunming Chen ◽  
Yogesh Jaluria
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Numerical Results ◽  
Fiber Drawing ◽  
Zonal Method ◽  
The Core ◽  
Optical Fiber Drawing ◽  
Cylindrical Furnace ◽  
Purge Gas ◽  
Energy Equations

Optical fibers are typically heated and drawn from silica preforms, which usually consist of two concentric cylinders called the core and the cladding, in a high-temperature furnace. For optical communication purpose, the core always has a higher refractive index than the cladding. In order to investigate the effect of core-cladding structure on the optical fiber drawing, a numerical model has been developed in this work. Axisymmetric flows of a double-layer glass and aiding purge gas in a concentric cylindrical furnace are considered. The thermal and momentum transport in both glass layers and gas are coupled at the interface boundaries. The neck-down profile is generated using an iterative scheme. The zonal method is applied to model the radiation transfer in the glass preform and the gas. Coordinate transformations are used to convert complex domains into cylinders. Stream function, vorticity and energy equations for the core, the cladding and the purge gas are solved by finite different methods using a false transient method coupled with an alternating direction implicit (ADI) method. A second order differencing scheme is used for discretization. The numerical results are validated by comparing with experimental and numerical results available in the literature.

scholarly journals Examination of the Implementation and Utilization of Optical Fibers Beams: A Review

2021 ◽  
Vol 8 (1) ◽  
pp. 201-206
Author(s):  
Mazullah Karimi
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Light Propagation ◽  
Monochromatic Light ◽  
Chemical Vapor ◽  
Refractive Index Profile ◽  
Typical Application ◽  
Processing Power ◽  
Natural Forms

For light propagation purposes, the optical fibers that are known as waveguides can be applied. A glass or plastic film called cladding covers the central portion of the optical fiber, and is distinguished by a refractive index that is lower relative to the main refractive index. For the fine confines of the light inside the waveguide, the overall internal reflection phenomena are necessary. It is possible to categorize optical fibers according to shape, number of modes, refractive index profile, dispersion, signal processing power, and polarization. We are concentrating on the first three typical forms of optical fibers in this article. This may be used in fiber beams as a typical application of fibers to generate and intensify a small, powerful beam of coherent and monochromatic light. Optical fiber processing requires three steps, such as the development of performs. The process of adjusted chemical vapor deposition (MCVD) is a recognized technique that can be used to manufacture optical fibers. Optical fiber sensors are well known in optics and photonics for their large variety of applications. Optical biosensors can be developed as a sensing application focused on refractive index changes that are commonly utilized for the identification of biomolecules in their natural forms.

Numerical Simulation of Transport in Optical Fiber Drawing with Core–Cladding Structure

2006 ◽  
Vol 129 (4) ◽  
pp. 559-567 ◽  
Author(s):  
Chunming Chen ◽  
Yogesh Jaluria
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Finite Difference Methods ◽  
Initial Study ◽  
Fiber Drawing ◽  
Zonal Method ◽  
The Core ◽  
Optical Fiber Drawing ◽  
Purge Gas

Optical fibers are typically drawn from silica preforms, which usually consist of two concentric cylinders called the core and the cladding, heated in a high-temperature furnace. For optical communication purposes, the core always has a higher refractive index than the cladding to obtain total internal reflection. In order to investigate the effect of this core–cladding structure on optical fiber drawing, a numerical model has been developed in this work. Axisymmetric flows of a double-layer glass and aiding purge gas in a concentric cylindrical furnace are considered. The thermal and momentum transport in both glass layers and gas are coupled at the interface boundaries. The neck-down profile is generated using an iterative numerical scheme. The zonal method is applied to model the radiation transfer in the glass preform. The gas is taken as nonparticipating. Coordinate transformations are used to convert the resulting complex domains into cylindrical regions. The stream function, vorticity, and energy equations for the core, the cladding, and the purge gas are solved by finite difference methods, using a false transient approach coupled with the alternating direction implicit method. A second-order differencing scheme is used for discretization. The numerical results are validated by comparing with results available in the literature. The effects of changes in the refractive index and absorption coefficient due to doping on fiber drawing are investigated. This problem has received very little attention in the literature, particularly with respect to modeling, and this paper presents an initial study of the underlying transport.

A Computational Investigation of Thermal Effects on Resin Coating Flows in an Optical Fiber Drawing System

2011 ◽  
Vol 110-116 ◽  
pp. 1080-1086
Author(s):  
Kyoung Jin Kim ◽  
Ho Sang Kwak ◽  
Jin Su Choi
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Thermal Effects ◽  
Resin Flow ◽  
Fiber Drawing ◽  
Coating Flows ◽  
Drawing Speed ◽  
Drawing System ◽  
Optical Fiber Drawing ◽  
Fiber Manufacturing

In manufacturing optical fibers, there has been intense research efforts of continually increasing fiber drawing speed to improve productivity. However, higher speed fiber drawing poses new challenge in many areas of optical fiber manufacturing. In this paper, thermal effects on coating resin flow in an unpressurized coating applicator are studied numerically. Present simulation results found that higher fiber drawing speed leads to severe viscous heating in coating resin flow and significant increase of resin temperature, which in turn leads to substantial viscosity decrease. These thermal effects profoundly alter the resin flow patterns and velocity profiles in the coating die and they should be considered in controlling the final coating thickness.

Metallization of Silica Optical Fibers

1998 ◽  
Vol 531 ◽  
Author(s):  
Robert W. Filas
Keyword(s):  
Chemical Vapor Deposition ◽  
Liquid Metal ◽  
Optical Fiber ◽  
Optical Fibers ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Fatigue Data ◽  
Silica Optical Fiber ◽  
Electroless Ni

AbstractA review is presented of metallization processes of silica optical fiber. Fiber strengths and fatigue data are summarized and compared for liquid metal freezing, chemical vapor deposition, sputtering, electroless and electrolytic coatings. Both continuous in-line and termination-only processes are considered. Details of an electroless Ni-P plating process are presented which can be used to prepare fiber ends for soldering into hermetic packages.

Heating and Burning of Optical Fibers and Cables by Light Scattered from Bubble Train Formed by Optical Fiber Fuse

2012 ◽  
Vol E95.B (8) ◽  
pp. 2638-2641 ◽  
Author(s):  
Makoto YAMADA ◽  
Akisumi TOMOE ◽  
Takahiro KINOSHITA ◽  
Osanori KOYAMA ◽  
Yutaka KATUYAMA ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers
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