Thermodynamic Properties and Optimized Fiber-Drawing Condition in Germanium Tellurite Glasses

2013 ◽  
Vol 275-277 ◽  
pp. 2002-2005
Author(s):  
Fang Fang Fu ◽  
Yu Lei ◽  
Jie Yang ◽  
Zhi Qiang Wang ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Optical Fibers ◽  
Coefficient Of Thermal Expansion ◽  
Softening Temperature ◽  
Optical Devices ◽  
Fiber Drawing ◽  
The Core ◽  
Onset Crystallization Temperature ◽  
Optical Fiber Drawing ◽  
Temperature Reference

Thermodynamic properties of the heavy metal germanium tellurite (NZPGT) core and cladding glasses have been investigated. Coefficient of thermal expansion (CTE) and softening temperature (Ts) of the Er3+⁄Yb3+ codoped NZPGT core glasses were identified to be 1.89×10–5 °C–1 and 343 °C, respectively. Glass transition temperature (Tg), onset crystallization temperature (Tx), peak temperature of crystallization (Tc), temperature difference value (ΔT) and thermal stability parameter (H) of the core glasses were solved to be 290 °C, 412 °C, 470 °C, 122 °C and 0.42, respectively, and the corresponding vaules of cladding glasses were derived to be 290 °C, 391 °C, 400 °C, 101 °C and 0.35. The investigation results indicate optical fiber drawing of Er3+⁄Yb3+ codoped medium-low phonon energy NZPGT glasses can be achieved in the temperature range 345—380 °C, which provides a valuable temperature reference for further high-quality optical fibers drawing in developing optical devices.

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.

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.

Thermodynamic Properties of Rare-Earth Ions Doped Lithium-Yttrium-Aluminium-Silicate Glasses

2013 ◽  
Vol 651 ◽  
pp. 232-236 ◽  
Author(s):  
Xiao Zhe Han ◽  
Yu Hua Li ◽  
Tie Cheng Ma ◽  
Zhi Qiang Wang ◽  
Xin Zhao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Thermodynamic Properties ◽  
Optical Fibers ◽  
Crystallization Temperature ◽  
Rare Earth Ions ◽  
Promising Candidate ◽  
Onset Crystallization Temperature ◽  
Yttrium Aluminium ◽  
Co Doped ◽  
Aluminium Silicate

hermodynamic properties including characteristic temperatures and thermal parameters of rare-earth (RE) ions doped lithium-yttrium-aluminium-silicate (LYAS) glasses have been investigated. Glass transition temperature (Tg), onset crystallization temperature (Tx), crystallization temperature (Tc), temperature difference value (DT) and Saad-Poulain criterion (S) in Tm3+/Yb3+ co-doped LYAS glasses are obtained to be 814, 1008, 1043, 194 and 8.34 °C, respectively, and the corresponding values of Sm3+ doped LYAS glasses are derived to be 825, 1002, 1053, 177 and 10.94 °C. Evaluations on thermodynamic properties indicate that LYAS glasses are a promising candidate for drawing optical fibers in the temperature range of 850−950 °C.

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.

scholarly journals Additivity of the coefficient of thermal expansion in silicate optical fibers

2017 ◽  
Vol 42 (18) ◽  
pp. 3650 ◽  
Author(s):  
M. Cavillon ◽  
P. D. Dragic ◽  
J. Ballato
Keyword(s):  
Thermal Expansion ◽  
Optical Fibers ◽  
Coefficient Of Thermal Expansion

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

Feasibility of High Speed Furnace Drawing of Optical Fibers

2004 ◽  
Vol 126 (5) ◽  
pp. 852-857 ◽  
Author(s):  
Xu Cheng ◽  
Yogesh Jaluria
Keyword(s):  
Optical Fibers ◽  
High Speed ◽  
Flow Instability ◽  
Fiber Quality ◽  
Domain Boundary ◽  
Operating Conditions ◽  
Furnace Temperature ◽  
Fiber Drawing ◽  
Heated Zone ◽  
Additional Information

The domain of operating conditions, in which the optical fiber-drawing process is successful, is an important consideration. Such a domain is mainly determined by the stresses acting on the fiber and by the stability of the process. This paper considers an electrical resistance furnace for fiber drawing and examines conditions for process feasibility. In actual practice, it is known that only certain ranges of furnace temperature and draw speed lead to successful fiber drawing. The results obtained here show that the length of the heated zone and the furnace temperature distribution are other important parameters that can be varied to obtain a feasible process. Physical behavior close to the boundary of the feasible domain is also studied. It is found that the iterative scheme for neck-down profile determination diverges rapidly when the draw temperature is lower than that at the acceptable domain boundary due to the lack of material flow. However, the divergence rate becomes much smaller as the temperature is brought close to the domain boundary. Additional information on the profile determination as one approaches the acceptable region is obtained. It is found that it is computationally expensive and time-consuming to locate the exact boundary of the feasible drawing domain. From the results obtained, along with practical considerations of material rupture, defect concentration, and flow instability, an optimum design of a fiber-drawing system can be obtained for the best fiber quality.

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