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Showing papers on "Bend radius published in 2004"


Journal ArticleDOI
Yurii A. Vlasov1, Sharee J. McNab1
TL;DR: The fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers with record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.
Abstract: We report the fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers. Owing to the small sidewall surface roughness achieved by processing on a standard 200mm CMOS fabrication line, minimal propagation losses of 3.6+/-0.1dB/cm for the TE polarization were measured at the telecommunications wavelength of 1.5microm. Losses per 90 masculine bend are measured to be 0.086+/-0.005dB for a bending radius of 1microm and as low as 0.013+/-0.005dB for a bend radius of 2microm. These record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.

999 citations


Journal ArticleDOI
TL;DR: An easy-to-evaluate expression for the prediction of the bend-loss for a large mode area photonic crystal fiber with a triangular air-hole lattice based on a recently proposed formulation of the V-parameter for a PCF and contains no free parameters is reported.
Abstract: We report on an easy-to-evaluate expression for the prediction of the bend-loss for a large mode area photonic crystal fiber (PCF) with a triangular air-hole lattice. The expression is based on a recently proposed formulation of the V-parameter for a PCF and contains no free parameters. The validity of the expression is verified experimentally for varying fiber parameters as well as bend radius. The typical deviation between the position of the measured and the predicted bend loss edge is within measurement uncertainty.

123 citations


Patent
Thomas William Haberman1
15 Dec 2004
TL;DR: In this article, a cable guide and a cable connector are disclosed for maintaining a desired bend radius, which includes two substantially curved tube halves, each tube half comprising a curved portion having a predetermined radius, and a fastening member configured to fasten the tube halves together.
Abstract: A cable guide and system are disclosed for maintaining a desired bend radius. The cable guide includes two substantially curved tube halves, each tube half comprising a curved portion having a predetermined radius. The cable guide also includes a hinge joining the tube halves and a fastening member configured to fasten the tube halves together. A first end of each of the tube halves is shaped to adhere to a cable connector. The cable connector terminates a cable. The tube halves have an open configuration and a closed configuration. When in the closed configuration, the tube halves are fastened together by the fastening member. In the closed configuration, the tube halves form a tubular sleeve. The tubular sleeve includes a lumen through which a cable may extend.

89 citations


Patent
01 Sep 2004
TL;DR: An optical fiber cable assembly comprising an optical fiber slidably enclosed within a hollow tubing, both the fiber and the tubing having corresponding first and second ends, is described in this paper, where the cable is terminated with the first two ends of the tubing and the fiber constrained with respect to each other such that fiber and tubing are approximately the same length when the cable was at a first temperature.
Abstract: An optical fiber cable assembly comprising an optical fiber slidably enclosed within a hollow tubing, both the fiber and the tubing having corresponding first and second ends The cable is terminated with the first and second ends of the tubing and the fiber constrained with respect to each other such that fiber and the tubing are approximately the same length when the cable is at a first temperature The tubing is made of a material which contracts more than the optical fiber when the cable is exposed to temperatures below the first temperature, such that the fiber is longer than the tubing and excess fiber length is formed An intermediate portion of the tubing permits the excess fiber length to accumulate without bending in a radius smaller than a minimum bend radius

83 citations


Patent
19 Nov 2004
TL;DR: In this article, a structural member bend radius sensor apparatus consisting of three fibre Bragg grating (FBG) strain sensors and three optical fibres 14, 16, 18 is presented.
Abstract: Structural member bend radius sensor apparatus 90 comprises three fibre Bragg grating (FBG) strain sensors 102 provided within three optical fibres 14, 16, 18. The optical fibres 14, 16, 18 and the FBGs 102 are embedded within a part-cylindrical shaped carrier member 92. The fibres 14, 16, 18 are provided at three spaced locations across the shaped carrier member 92 so that, in use, the three respective FBG strain sensors will be located at three different angular positions around the circumference of the structural member (pipe) 68. Structural member shape measurement apparatus 100 comprises four bend radius sensor apparatus 90 provided at four bend radius measurement positions along the pipe 68. The four bend radius sensor apparatus 90 shown share their optical fibres 14, 16, 18, and a single shaped carrier member 92. The shape measurement apparatus 100 further comprises FBG interrogation apparatus 104.

79 citations


Journal ArticleDOI
TL;DR: In this paper, a wrinkling wave function is proposed and a simplified wrinkling prediction model to predict the minimum bending radius for tubes is established based on thin-shell theory, forming theory, the energy principle and wave function.

75 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of air velocity, bend radius and number of repeated impacts were investigated for three commercially available feeds in a 100mm diameter pipeline, and the volume independent 37% Weibull tensile strength was used to normalise the pellet strength.

69 citations


Journal ArticleDOI
TL;DR: In this article, a single-stage S-band erbium-doped fiber amplifier is proposed, where distributed suppression of C-band amplified spontaneous emission is provided by optimized bend loss in a coaxial core fiber.
Abstract: We propose a novel compact design for a single-stage S-band erbium-doped fiber amplifier, wherein distributed suppression of C-band amplified spontaneous emission is provided by optimized bend loss in a coaxial core fiber. Simulations show that /spl sim/25-dB unsaturated gain over 30-nm bandwidth (1495-1525) nm is achievable with the designed module, using a nominal pump power of 500 mW. The noise figure of the amplifier varies between 4.5 and 8 dB from 1495 to 1525 nm. By proper designing, we have also ensured that the gain ripple over the entire 30-nm bandwidth is

62 citations


Journal ArticleDOI
TL;DR: In this paper, the propagation of surface plasmon polaritons about a metallic corner with a finite bend radius was analyzed using a one-dimensional model analogous to the scattering from a finite-depth potential well.
Abstract: We analyze theoretically the propagation of surface plasmon polaritons about a metallic corner with a finite bend radius, using a one-dimensional model analogous to the scattering from a finite-depth potential well. We obtain expressions for the energy reflection and transmission coefficients in the short wavelength limit, as well as an upper bound for the transmittance. In certain cases we find that propagation on nonplanar interfaces may result in lower losses than on flat surfaces, contrary to expectation. In addition, we also find that the maximum transmittance depends nonmonotonously on the bend radius, allowing increased transmission with decreasing radius.

32 citations


Journal ArticleDOI
TL;DR: In this article, the propagation of surface plasmon polaritons about a metallic corner with a finite bend radius was analyzed using a one-dimensional model analogous to the scattering from a finite-depth potential well.
Abstract: We analyze theoretically the propagation of surface plasmon polaritons about a metallic corner with a finite bend radius, using a one-dimensional model analogous to the scattering from a finite-depth potential well. We obtain expressions for the energy reflection and transmission coefficients in the short wavelength limit, as well as an upper bound for the transmittance. In certain cases we find that propagation on non-planar interfaces may result in lower losses than on flat surfaces, contrary to expectation. In addition, we also find that the maximum transmittance depends non-monotonously on the bend radius, allowing increased transmission with decreasing radius.

27 citations


Proceedings ArticleDOI
30 Nov 2004
TL;DR: In this paper, the authors measured the damage threshold of 8 μm and 22 μm-core diameter hollow-core photonic band gap (PBG) fibres with a 1.06 μm Nd:YAG laser (30 nsec pulses at 10 Hz).
Abstract: Laser damage thresholds of 8 μm- and 22 μm-core diameter solid-core photonic crystal fibres (PCF) and hollow-core photonic band gap (PBG) fibres have been measured. The studies were carried out using a 1.06 μm Nd:YAG laser (30 nsec pulses at 10 Hz), which is optimally coupled into these fibres by careful mode matching, providing a coupling efficiency greater than 90%. It has been shown that the damage threshold of the 8 μm core PBG fibre occurs at pulse energies close to 1 mJ, equivalent to a fluence well in excess of 1 kJ/cm 2 propagating down the fibre. This is a factor of 4 larger than the damage threshold of a solid-core PCF of similar core diameter. In comparison, the damage threshold of the large-core PBG is smaller than that of the equivalent PCF. Theoretical modelling based only on the optical modal properties of the single-mode PBG fibre shows that an enhancement by a factor of 25 should be obtainable. Thus there are different damage mechanisms potentially responsible for the fragility of larger-core PBG fibres. In an experimental study of bend losses it has been found that it is possible to bend the 8 μm PBG fibre up to the breaking point bend radius (<1 mm). The critical bend radius for the 22 μm core PBG is close to 2 mm, which is 50 times smaller than the critical bend radius of a 20 μm core PCF.

Journal ArticleDOI
TL;DR: In this paper, a plasma enhanced chemical vapor deposition process was developed to deposit SiO 2 -GeO 2 films suitable for high index contrast planar waveguides, and the films were deposited in a standard parallel plate reactor from silane, germane, nitrous oxide, and a nitrogen carrier.
Abstract: A plasma enhanced chemical vapor deposition process was developed to deposit SiO 2 -GeO 2 films suitable for high index contrast planar waveguides. These films were deposited in a standard parallel plate reactor from silane, germane, nitrous oxide, and a nitrogen carrier. The germania content of the film was equal to the mole fraction germane of the hydride precursors in the gas stream, and the refractive index of the film varied linearly with the mole fraction of germania. Low loss guides ranging from 1.5-4.0% Δ were fabricated. With standard photolithographic patterning, a 0.05 dB/cm propagation loss and minimum bend radius of 1.5 mm were measured for 2.0% A. Improvements to the photolithographic patterning to reduce sidewall roughness were required to achieve low propagation loss at higher Δ. This reduced the propagation loss for 3.5% Δ cores to 0.086 dB/cm. An average minimum bend radius of 570 μm was measured for 3.5% A, but modeling suggests the bend radius could be reduced below 500 μm with offsets to reduce transition loss. Ring resonator, fabricated from 3.5% A waveguides, exhibited a free spectral range as large as 62.7 GHz and a very low round trip insertion loss of 0.06 dB.

Journal ArticleDOI
TL;DR: In this paper, the influence of the bend radius ratio and the gas inlet velocity in a U-bend is investigated for single-phase and multiphase isothermal flow.
Abstract: The incompressible, single-phase and multiphase, isothermal and steady-state flows in a U-bend are studied numerically using FLUENT 6.0. A basic understanding of gas–solid flow and pressure behavior in a U-bend is frequently required to obtain better U-bend design, for example, in pneumatic conveying dryers. Fyhr and Rasmuson found that U-bends significantly influence the drying behavior in such a dryer since they enhance velocity differences (slip) between suspended material and the drying medium. For single-phase flow, influences of the gas inlet velocity and the bend radius ratio on the velocity and pressure profiles in a U-bend are studied. The numerical calculations were validated against experimental data from the literature. The gas inlet velocity varies from 5 up to 25 m s−1 while the bend radius ratio varies from 2 up to 8 m m−1, The gas inlet velocity has a strong influence on the total pressure drop of the system and the bend radius ratio strongly affects the velocity and pressure profiles in a U-bend. For multiphase flow, the bend radius ratio was varied from 3 up to 8 with constant gas velocity of 15 m s−1. There are three important effects of the U-bend: increase in slip velocity; an accumulation of particles along the outer walls of the U-bend and the beginning of downstream pipe; and an increase in pressure drop. A higher slip velocity and a better dispersion of particles are desired for a pneumatic conveying drying system while an increase in pressure drop is not favorable. Choice of the appropriate velocity and bend shape can, therefore, be utilized in the overall optimization of the operating conditions of pneumatic conveying systems.

Journal ArticleDOI
TL;DR: In this paper, an incremental in-plane bending machine for short production runs in a variety of sizes and shapes is described, where a strip of sheet metal is bent incrementally by an inclined punch beating according to the control program.

Patent
27 Aug 2004
TL;DR: In this paper, a structural member bend radius sensor apparatus consisting of three fibre Bragg grating (FBG) strain sensors and three optical fibres 14, 16, 18 is presented.
Abstract: Structural member bend radius sensor apparatus 90 comprises three fibre Bragg grating (FBG) strain sensors 102 provided within three optical fibres 14, 16, 18. The optical fibres 14, 16, 18 and the FBGs 102 are embedded within a part-cylindrical shaped carrier member 92. The fibres 14, 16, 18 are provided at three spaced locations across the shaped carrier member 92 so that, in use, the three respective FBG strain sensors will be located at three different angular positions around the circumference of the structural member (pipe) 68. Structural member shape measurement apparatus 100 comprises four bend radius sensor apparatus 90 provided at four bend radius measurement positions along the pipe 68. The four bend radius sensor apparatus 90 shown share their optical fibres 14, 16, 18, and a single shaped carrier member 92. The shape measurement apparatus 100 further comprises FBG interrogation apparatus 104.

Patent
28 Dec 2004
TL;DR: In this paper, a single-mode optical fiber that propagates an optical signal at a wavelength of 1310 nm, in singlemode operation, has a mode field diameter of 6.6 μm or more at the wavelength of 1410 nm; and a macro bending loss of at most 0.1 dB/10 turns with a bending radius of 7.5 mm at a length of 1650 nm.
Abstract: Provided is a single-mode optical fiber that propagates an optical signal at a wavelength of 1310 nm, in single-mode operation; has a mode field diameter of 6.6 μm or more at the wavelength of 1310 nm; and a macro bending loss of at most 0.1 dB/10 turns with a bending radius of 7.5 mm at a wavelength of 1650 nm.

Patent
12 Jul 2004
TL;DR: A cover fitting for connecting more than one raceway includes an L-shaped top having first and second curved grooves extending along the inner surface of the top and a plurality of hooks extending outwardly from the inner surfaces for engaging a portion of each raceway base as mentioned in this paper.
Abstract: A cover fitting for connecting more than one raceway includes an L-shaped top having first and second curved grooves extending along the inner surface of the top and a plurality of hooks extending outwardly from the inner surface for engaging a portion of each raceway base. The cover fitting further includes first and second opposing sides extending from the inner surface of the top. The cover fitting can be used with a fitting base received in first and second grooves for situations requiring a specific bend radius, or in applications without a fitting base, where there are no bend radius requirements.

Patent
01 Jul 2004
TL;DR: In this article, a machine is used for continuous bending of long products to a predetermined radius by using three parallel contact-free distance meters (laser transmitters) and measuring the distances to the bent surface on the product, by calculating the actual bending radius based on the fixed distances between the meters and the measured distances, and controlling the adjustment of the machine in response to the relation between the calculated actual radius and the desired radius.
Abstract: A machine is process monitored and controlled for continuous bending of long products to a predetermined radius by using three parallel contact-free distance meters (laser transmitters) and by measuring the distances to the bent surface on the product, by cal­culating the actual bending radius based on the fixed distances between the meters and the measured distances, and controlling the adjustment of the machine in response to the relation between the calculated actual radius and the desired radius. The machine comprises a processor for performing said calculation and controlling the bending device.

Patent
26 Apr 2004
TL;DR: In this paper, a pull cable can restrain cable curvature by the use of cable links configured to provide a limit to a range of an angular relationship between neighboring cable links, by limiting the angular variation between links.
Abstract: A pull cable can restrain cable curvature by the use of cable links configured to provide a limit to a range of an angular relationship between neighboring cable links. By limiting the angular variation between links, a minimum radius of the pull cable can be provided. The cable links can inhibit kinking of the inner cable by restricting the cable from reaching a small radius that could induce kinking.

Journal ArticleDOI
TL;DR: In this article, numerical analysis was used to explore ways for reducing bending losses in silicon-on-insulator ridge waveguides with different sizes, and the results obtained were used in a numerical optimization of an S-bend structure.
Abstract: In this work numerical analysis was used to explore ways for reducing bending losses in silicon-on-insulator ridge waveguides. Bending losses in single-mode ridge waveguides with different sizes were calculated. The results obtained were used in a numerical optimization of an S-bend structure. Also, the loss reduction achieved by placing a groove along the side of a bend was determined. Calculations were made for both TE and TM polarizations at 1550nm wavelength. Smaller waveguides were found to cause much smaller bending losses. The groove structure allows the use of ten times smaller bending radii. With the groove, a ridge waveguide with 1.5µm thickness and 75µm bending radius was found to have only 0.7dB loss in a 90° turn, when both bending and junction losses were taken into account. The numerical path optimization of an S-bend halved the total loss in dB.

Journal ArticleDOI
TL;DR: In this article, a qualitative three-level model of the attrition process, involving stress mode, material-specific attrition mechanisms and basic (microscopic) attrition mechanisms, was developed.

Proceedings ArticleDOI
25 Oct 2004
TL;DR: In this paper, the authors proposed using Bragg reflectors surrounding the microring to reduce loss for improved performance, and simulation shows feasibility of this approach and provides evaluation of the trade-offs.
Abstract: A microring resonator, a circular waveguide adjacent to a straight waveguide, performs selective band-stop filtering for optical telecommunications. Small size and versatility of functionality allow many microrings to be incorporated into a single integrated optic circuit. We desire small size, less than 20 micron radius; low insertion loss in band-stop outside resonance; perfect cancellation to zero in band-stop at resonance; and low refractive index difference between core and cladding. These requirements are conflicting: conventional silicon waveguides cannot achieve low enough loss at the desired bend radius. Current approaches use different materials with higher refractive index differences. Analysis and simulation provide evaluation of the trade-offs. Further, we propose, for the first time, conventional waveguides using Bragg reflectors surrounding the microring to reduce loss for improved performance. Simulation shows feasibility of this approach.

Journal ArticleDOI
TL;DR: In this paper, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated, and different buckling modes are also considered.
Abstract: This paper discusses the stability of underground pipelines with preformed vertical bends buried in sandy soil. More specifically, the minimum cover height required to prevent the pipe from bowing under the action of forces due to temperature change and internal pressure is estimated. The variables considered include the pipe and soil materials, diameter, thickness, overburden height, bend radius, bend angle, internal pressure, fluid specific weight, and temperature variation. A comprehensive three-dimensional finite element analysis is carried out. The results are extracted from the output obtained. These results are put in a database which is used to develop general regression models to determine the relationships among the different variables. Different buckling modes are also considered. All of these results and models are entered into a computer software program for ready access.

Patent
20 Jan 2004
TL;DR: In this article, a cable clip includes a housing defining an open space and outer grooves about the housing for mounting the cable clip into a mounting opening, the inner edge of the housing including trumpet flares around the edges of the ends and side to provide bend radius protection for cables passing through the clip and a gate closing off the open sided space.
Abstract: A cable clip includes a housing defining an open space and outer grooves about the housing for mounting the cable clip into a mounting opening, the inner edge of the housing including trumpet flares around the edges of the ends and side to provide bend radius protection for cables passing through the clip and a gate closing off the open sided space. The gate may be attached to the housing by a living hinge.

Proceedings ArticleDOI
16 Jul 2004
TL;DR: A 10 T racetrack magnet (HFDB•03) wound with pre-reacted Nb3Sn Rutherford cable has been fabricated and tested at Fermilab as discussed by the authors.
Abstract: A 10 T racetrack magnet (HFDB‐03) wound with pre‐reacted Nb3Sn Rutherford cable has been fabricated and tested at Fermilab. This magnet is the third one in a proof‐of‐principle series for the use of the React‐and‐Wind technology in common‐coil dipole magnets for future accelerators. It consists of two flat racetrack coils (28 turns each) separated by 5 mm. The maximum field on the coil, at the short sample limit of 16530 A, is 10 tesla. The cable has 41 strands with 0.7 mm diameter and the minimum bend radius in the magnet ends is 90 mm. The predecessor of this magnet (HFDB‐02) reached 78 % of the short sample limit at 7.7 T. The mechanical design was improved and the fabrication procedure was slightly modified in order to address possible causes of limitation. In this paper we present the mechanical design and analysis of HFDB‐03, the modifications to the fabrication procedure and the test results.

Proceedings ArticleDOI
14 Jun 2004
TL;DR: In this article, the design of small waveguide modulators (of the order of ~1 micron) together with a presentation of preliminary experimental results are discussed, based on injection of free carriers via a p-i-n device, and via thermal modulation of a ring resonator.
Abstract: In silicon based photonic circuits, optical modulation is usually performed via the plasma dispersion effect or via the thermo-optic effect, both of which are relatively slow processes. Until relatively recently, the majority of the work in Silicon-on-Insulator (SOI) was based upon waveguides with cross sectional dimensions of several microns. This limits the speed of devices based on the plasma dispersion effect due to the finite transit time of charge carriers, and on the thermo-optic effect due to the volume of the silicon device. Consequently moving to smaller dimensions will increase device speed, as well as providing other advantages of closer packing density, smaller bend radius, and cost effective fabrication. As a result, the trend in recent years has been a move to smaller waveguides, of the order of 1 micron in cross sectional dimensions. In this paper we discuss both the design of small waveguide modulators (of the order of ~1 micron) together with a presentation of preliminary experimental results. In particular two approaches to modulation are discussed, based on injection of free carriers via a p-i-n device, and via thermal modulation of a ring resonator.

Patent
17 Nov 2004
TL;DR: In this article, a manufacturing method for reinforcement twisted wire of glass fiber and carbon fiber, the product is made up of a centre silk material and several glass fibers and carbon fibers which are twisted, the invention uses I-shaped plate whose radius is 20 mm bigger than the minimal bending radius as draw drum, the inner radius of the take-up plate is at least bigger than a minimal bend radius of reinforcement twisted wires about 50mm.
Abstract: The invention is a manufacturing method for reinforcement twisted wire of glass fiber and carbon fiber, the product is made up of a centre silk material and several glass fiber and carbon fiber which are twisted, the invention uses I-shaped plate whose radius is 20 mm bigger than the minimal bending radius as draw drum, the inner radius of the take-up plate is at least bigger than the minimal bending radius of reinforcement twisted wire about 50mm; the bending radius in process of extracting can't be less than the inner radius of the I-shaped plate. The adhesive is painted on the centre silk material, then heating and solidifying them. The invention absorbs the forming theory of steel twisted wire, combines with the character of FRP silk material.

Proceedings ArticleDOI
28 May 2004
TL;DR: In this article, an air trench bend consists of cladding tapers to avoid junction loss, providing adiabatic mode shaping between low and high index contrast regions, and a simple, compact waveguide and T-splitter are fabricated and evaluated.
Abstract: Air trench structure for reduced-size bends in low (Δn=0.01-0.1) and medium (Δn=0.1-0.3) index contrast waveguides is proposed. Local high index contrast at bends is achieved by introducing air trenches. An air trench bend consists of cladding tapers to avoid junction loss, providing adiabatic mode shaping between low and high index contrast regions. Drastic reduction in effective bend radius is achieved. We present FDTD simulations of bends in representative silica index contrasts, fabrication scheme and waveguide loss measurement results using Fabry-Perot loss measurement technique. We employed CMOS compatible processes to realize air trench bends and T-splitters to achieve low production cost and high yield. A simple, compact waveguide and T-splitter are fabricated and evaluated. The loss measurement results show that losses are consistent with theoretical simulations. By using air trench waveguides, other applications such as BioMEMS (e.g. Evanescent-field sensor) or EDWA can be realized.

Patent
23 Dec 2004
TL;DR: In this paper, a production apparatus for bending a multi-channel tube having an outer tube and a partition partitioning an interior of the outer tube into two or more channel holes is provided.
Abstract: A production apparatus for bending a multi-channel tube having an outer tube and a partition partitioning an interior of the outer tube into two or more channel holes is provided with a bending mold configured to bend the multi-channel tube in a bend radius; a pressure mold configured to press the multi-channel tube toward the bending mold; a chuck portion configured to hold and draw the multi-channel tube along the bending mold; and mandrels respectively inserted into the channel holes, each of the mandrels including; a mandrel body configured to support inner surfaces of each channel hole; a support device rotatably and movably supporting the mandrel body.

Patent
20 Feb 2004