Showing papers on "Bend radius published in 2009"

Low loss etchless silicon photonic waveguides

Abstract: We demonstrate low loss silicon waveguides fabricated without any silicon etching. We define the waveguides by selective oxidation which produces ultra-smooth sidewalls with width variations of 0.3 nm. The waveguides have a propagation loss of 0.3 dB/cm at 1.55 μm. The waveguide geometry enables low bending loss of approximately 0.007 dB/bend for a 90° bend with a 50 μm bending radius.

Low loss etchless silicon photonic waveguides

Abstract: We demonstrate low loss silicon waveguides fabricated without silicon etching by selective oxidation. We show propagation losses of 0.3dB/cm (λ=1.55µm), roughness of 0.3nm RMS, and 0.0002dB loss for a 90° bend with 20µm bending radius.

Ultra-Low Bending Loss Single-Mode Fiber for FTTH

Abstract: A new ultra-low bending loss single-mode fiber with ring comprising nanometer sized features is designed and manufactured. Bending loss less than 0.1 dB/turn at 1550 nm and a bend radius of 5 mm is demonstrated. Other optical parameters of the fiber are fully compatible the standard telecommunications grade single-mode fibers.

Compact and low power thermo-optic switch using folded silicon waveguides

Abstract: By exploiting the small bend radius achievable using high-index-contrast silicon photonic wire waveguides, we demonstrate a new low power thermo-optic switch arranged in a dense, double spiral geometry. Such a design permits the waveguide length to be extended for increased phase shift, without the need for increased heated volume. This provides an effective means to reduce the power consumption of thermo-optic switches, as well as a compact geometry desirable for the development of switch arrays. A low switching power of 6.5 mW was obtained for a spiral-path Mach-Zehnder interferometer device having a 10% - 90% rise time of 14 micros. The switching power is shown to be reduced by more than 5 times compared to a Mach-Zehnder interferometer employing a conventional straight waveguide geometry.

Fabrication and Characterization of Small Optical Ridge Waveguides Based on SU-8 Polymer

Abstract: Small SU-8 ridge optical waveguides with an air cladding and a SiO2 buffer on Si substrate have been realized by using a direct ultraviolet (UV) photolithography technology. The propagation loss measured by the cut-back method is about 0.1 dB/mm (@1550 nm) when the core width is 2.8 ?m. The bending losses of the present SU-8 optical ridge waveguides are also characterized. The measured results show that the bending loss decreases exponentially as the bending radius increases and the total loss can be reduced effectively by introducing an appropriate offset between two connected sections with different curvatures. A small bending radius (as small as 75 ?m) is still allowed for the requirement of a small bending loss (< 0.1 dB) when an offset of 0.1 ?m is introduced. Finally, by using this kind of waveguide, a small 1 × 2 Y-branch power splitter is fabricated and characterized.

Characterization of Long-period Grating Refractive Index Sensors and Their Applications

Abstract: The influence of grating length and bend radius of long-period gratings (LPGs) on refractive index sensing was examined. Sensitivity to refractive indexes smaller than that of silica could be enhanced by bending LPGs. Bent LPGs lost sensitivity to refractive indexes higher than that of silica, whereas a 20-mm-long LPG arranged in a straight line had considerable sensitivity. These experimental results demonstrated that the sensitivity characteristics of LPGs to refractive index could be controlled by grating length and bend radius.

Fiber Optic Distribution Device and Fiber Optic Network Including the Same

Abstract: A fiber optic distribution device, comprising a housing; said housing providing an inlet opening for an fiber optic riser cable or for an fiber optic tether cable and an outlet opening for said fiber optic riser cable or for said fiber optic tether cable, whereby said inlet opening is assigned to a first side wall of the housing and said outlet opening is assigned to a second, opposite first side wall of the housing; said housing having a third side wall extending between said first side wall and said opposite second side wall, whereby outlet openings for fiber optic drop cables and/or adapters for fiber optic connectors being assigned to said third side wall; said housing further having a bottom wall, whereby at least two spaced apart lines of bend radius control elements are assigned to said bottom wall; whereby each line of bend radius control elements runs in parallel to said third side wall; and whereby in the middle between each two adjacent bend radius control elements of the first line there is positioned each one bend radius control element of the second line thereby providing each two guide channels, namely a first guide channel for guiding optical fibers from the third side wall to the first side wall and a second guide channel for guiding optical fibers from the third side wall to the second side wall.

Spring-back deformation in tube bending

Abstract: The spring-back of a bending metal tube was studied through extensive experiments and finite element method (FEM) analysis. An approximate equation for the spring-back angle of bending was deduced. It is noted that the mechanical properties of the material (in a tubular form) are quite different from those found in the standard tensile tests (when the materials are in bar forms). This is one of the major reasons that result in the discrepancies in the outcomes of experimental study, FEM calculations, and spring-back analysis. It is therefore of crucial importance to study the mechanical properties of the materials in their tubular forms. The experiments and FEM simulations prove that the spring-back angle is significantly affected by the mechanical properties of the materials. The angle decreases accordingly with plastic modulus, but changes inversely with the hardening index and elastic modulus. The spring-back angle is also affected by the conditions of tube deformation: it increases accordingly with the relative bending radius but changes inversely with the relative wall thickness. In addition, the spring-back angle increases nonlinearly with the bending angle.

Comparative Study of Losses in Ultrasharp Silicon-on-Insulator Nanowire Bends

Abstract: Ultrasharp silicon-on-insulator (SOI) nanowire bends (with a bending radius of R < 2 mu m) are analyzed numerically. It is shown that the calculated bending losses for ultrasharp bends are overestimated when using a modal analysis method based on finite-difference method. In this case, reliable estimation of the bending loss can be made with a 3-D finite-difference time-domain (3-D-FDTD) method. By using 3-D-FDTD simulation, the losses in SOI nanowire bends with different structures and parameters are studied. By increasing the core width or height of the waveguide, one can reduce the bending loss at longer wavelengths for TE mode while the bending performance at shorter wavelengths degrades due to the multimode effect. Increasing the core height is much more effective to reduce the bending loss of TM mode than increasing core width. The relationship between the intrinsic Q-factor of a microring resonator and the bending radius is also obtained.

Vertically integrated As2S3 ring resonator on LiNbO3.

Abstract: Titanium-diffused lithium niobate (Ti:LiNbO(3)) waveguides are widely used in current fiber optic networks because of their high-speed, electro-optic modulation, and low-loss integration with standard single-mode fibers. However, they cannot achieve small ring resonators owing to their lack of a high core-to-cladding index contrast. To overcome this challenge, we vertically integrate an emerging chalcogenide glass waveguide technology on well-established Ti:LiNbO(3) waveguides. We present, to our knowledge, the first arsenic trisulfide (As(2)S(3)) race-track ring resonator with a 290.8 microm bend radius in an all-pass filter configuration, integrated on a Ti:LiNbO(3) waveguide. Vertical coupling is achieved using a unique taper design. Experimental results are shown for 10.6% coupling, 2.08 dB roundtrip loss, and a 25.4 GHz free-spectral range.

Numerical analysis of index-guiding photonic crystal fibers with low confinement loss and ultra-flattened dispersion by fdfd method

Abstract: In this article, perfectly matched layer (PML) for the boundary treatment and an efficient compact two dimensional finite-difference frequency-domain (2-D FDFD) method were combined to model photonic crystal fibers (PCF). For photonic crystal fibers, if we assume that the propagation constant along the propagation direction is fixed, three- dimensional hybrid guided modes can be calculated by using only a two-dimensional mesh. An index-guiding PCF with an array of air-holes surrounding the silica core region has special characteristics compared with conventional single-mode fibers (SMFs). Using this model, the fundamental characteristics of single mode photonic crystal fibers (SMPCFs) such as confinement loss, bending loss, effective mode area and chromatic dispersion are numerically investigated. The results revealed that low confinement loss and zero-flattened chromatic dispersion can be obtained by varying the air-holes diameter of each ring along the PCF radius. In this work, an especial PCF with nearly zero-flattened dispersion (1.3 ps/nm/km) over a wide wavelength range which covers O, E, S, C, L and U telecommunication wavelength bands and low confinement loss (0.06 dB/km at 1.55μm) is designed. Macro-bending loss performance of the designed PCF is also studied and it is found that the fiber shows low bending losses for the smallest feasible bending radius of 5 mm. Also, it is revealed that the temperature sensitivity of PCFs is very low in compared with the conventional fibers.

Characterization and prediction of meandering channel migration in the GIS environment: A case study of the Sabine River in the USA

Abstract: This study focused on the prediction of a 22 km meandering channel migration of the Sabine River between the states of Texas and Louisiana. The meander characteristics of 12 bends, identified from seven orthophotos taken between 1974 and 2004, were acquired in a GIS environment. Based on that earlier years’ data acquisition, channel prediction was performed for the two years 1996 and 2004 using least squares estimation and linear extrapolations, yielding a satisfactory agreement with the observations (the median predicted and observed migration rates were 3.1 and 3.6 [m/year], respectively). The best-predicted migration rate was found to be associated with the longest orthophoto-recorded interval. The study confirmed that channel migration is strongly correlated with bend curvature and that the maximum migration rate of the bend corresponded to a radius of curvature [bend radius (RC)/channel width (WC)] of 2.5. In tight bends of a smaller radius of curvature than 1.6, secondary flow scouring near the bend apex increases bend curvature. The stability index of the dimensionless bend radius was determined to be 2.45. Overall, this study proves the effectiveness of least squares estimation with historical orthophotography for characterization of meandering channel migration.

Three-dimensional modelling of scattering loss in InGaAsP/InP and silica-on-silicon bent waveguides

Abstract: A three-dimensional (3D) method for the estimation of scattering loss due to sidewalls roughness in bent optical waveguides is proposed and validated. The approach, based on Volume Current Method (VCM), has been pointed out to accurately calculate the scattering loss as dependent on curvature radius and wavelength. An exponential model has been employed to analytically describe the sidewalls roughness and a 3D mode solver based on mode-matching method has been used to calculate optical field distribution in the bent waveguide cross-section. Scattering loss suffered by two low index contrast waveguides has been investigated by the developed algorithm. For a buried InGaAsP/InP waveguide and a 6 μm x 6 μm Silica-on-Silicon guiding structure scattering loss dependence on bending radius, wavelength, roughness, correlation length and standard deviation has been investigated and discussed. Because of the different index contrast values, InGaAsP/InP waveguide exhibits a scattering loss which is quite six times larger than in Silica-on-Silicon. For both guiding structures, quasi-TM mode shows a larger scattering loss than quasi-TE one.

Mid-plane mounted optical communications system and method for providing high-density mid-plane mounting of parallel optical communications modules

Abstract: An optical communications system and method are provided in which multiple parallel optical communications modules are mid-plane mounted on a PCB motherboard. Each module is connected to an optical fiber ribbon cable. The modules are configured to have very low profiles and/or to provide an angular coupling of the ribbon cable to the module. In both cases, the module configurations obviate the need to leave a significant amount of space between a module and the one behind it for the purpose of providing room for the ribbon cable to exit the module without the cable being bent beyond its minimum bend radius. This feature allows the module mounting density on the motherboard PCB to be very high and allows the modules to be mounted closer to their respective hub ICs, which increases mounting density and allows the modules to be mounted closer to their respective hub ICs.

Fabrication and characterization of straight and compact S-bend optical waveguides on a silicon-on-insulator platform.

Abstract: Straight and S-bend rib waveguide structures with a novel design have been fabricated and characterized on a silicon-on-insulator (SOI) platform. For a typical straight rib waveguide, the single-mode waveguide at λ~1550 nm has been verified by measuring the near-field output with an IR camera, and a nearly polarization-independent mode size is found to be ~10 μm×4.5 μm. The waveguide loss has been estimated from low-finesse Fabry-Perot transmission characteristics, and a typical value of ~0.5 dB/cm is obtained. It is also shown experimentally that the bending radius of an asymmetrically etched S-bend waveguide can be ten times smaller than that of conventional symmetrically etched S-bend waveguides for similar optical losses. These bend waveguides (bending radii of ~1500 μm) are found to be low loss (<2.5 dB) and nearly polarization independent.

Optical fiber cable and optical fiber tape

Abstract: Provided is a single-core coated optical fiber (11) having such a curve loss characteristic that an optical loss increase at a bending radius 13 mm is 0.2 dB/10 turn or below. An optical fiber tape conductor includes two-dimensionally arranged resin portions (18) for bonding each two adjacent single-core coated optical fibers (11). The resin portions (18) are arranged apart from one another in the longitudinal direction of the optical fiber tape conductor. An optical fiber cable includes a cable core unit for containing a plurality of sets of the single-core coated optical fibers (11) constituting the optical fiber tape conductor which are twisted together.

High tensile and bend resistant movables cable conductor

Abstract: The invention discloses a high tensile and bend resistant movable cable conductor. The cable conductor comprises a tensile wire layer positioned in an inner layer and formed by adopting a plurality of strands of aramid silk fiber strands and multiple strands and a conductor layer formed by respectively enwinding a plurality of homocentric tinning annealed copper wires or annealed bare copper wires on the tensile wire layer. The enwinding directions of each layer of tinning annealed copper wires or annealed base copper wires are opposite from inside to outside. The invention can be taken as the conductor of various movable cables; the cables can freely move, have smaller bending radius, and can freely move along with a movable device, and the conductor service life thereof can be improved to tens of times.

Compact Microracetrack Resonator Devices Based on Small SU-8 Polymer Strip Waveguides

Abstract: Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n~1.573) , a SiO2 buffer (n~1.445), and an air cladding. The fabricated straight waveguide has a low propagation loss of about 0.1 dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (~150 mum) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.

All-solid G.652.D fiber with ultra low bend losses down to 5 mm bend radius

Abstract: We demonstrate the feasibility of all-solid G.652.D fibers that exhibit bend losses 10 times lower than ITU-T recommendation G.657.B and 0.05 dB/turn at 5 mm bend radius at 1550 nm.

Smooth and flexible clean room hose

Abstract: A hose suited for use in clean rooms has a Minimum Bend Radius (MBR) that is flexible without kinking. The hose includes a germ and bacteria resistant smooth outer surface and is constructed form a low modulus rubber type matrix with primary reinforcement layers laid at optimal opposing angles around a thin walled thermoplastic liner and similarly a secondary reinforcement layer of wire is utilized.

Bend insensitive fiber for FTTX applications

Abstract: FTTH applications require advanced fibers insensitive to stapling and tight bends. We demonstrate resonance-assisted fibers made with standard solid-fiber fabrication, achieving ≪0.1dB/turn loss down to 3mm fiber bend radius and compatibility with standard SMF.

Arc welding robot

Abstract: An arc welding robot having a welding wire conduit which has a bend radius above a certain level and arranged so that disadvantageous stress is not applied to the conduit by the motion of the robot arm. A conduit for a welding wire is inserted through a hole of a robot pedestal from the rear side of the robot, is supported by a second support member arranged on the pedestal, extends near the front side of a rotating body of the robot, and is supported by a first support member on the upper part of the rotating body while having a required minimum bend radius. The conduit after passing through the first support member is introduced to the rear side of the upper arm and is connected to a connector at the rear side of a wire feeder while having the required minimum radius, whereby the conduit presents a generally S-shape.

Investigations on Three-Roll Bending of Plain Tubular Components

Abstract: Bent metal tubes find a widespread application in many industrial sectors. Among different bending processes developed for the manufacturing of these components, three-roll bending is characterized by a high flexibility, as only one toolkit per tube diameter is necessary to form the required bending radius. In this type of forming process the part geometry is obtained by means of a relative movement of the die (setting roll) towards the fixed tools (bending and holding roll) with simultaneous feeding of the tube. This study describes the FE-model developed for the three-roll bending and presents first results of numerical investigations conducted on steel tubes made of carbon steel St37. By the FE-analysis great attention is paid on the modeling of the stiffness of the tool, on the description of the kinematics of the setting roll as well as on the characterization of the material behavior for the simulation. The results of the numerical investigations are compared with experiments conducted with a CNC-bending machine available at the Chair of Manufacturing Technology of the University of Erlangen. As a main criterion for the validation of the FE-model the radius of the tube at the extrados and the bending angle are chosen. The geometry of the part is measured by means of both optical and tactile measuring devices.

Radio frequency coaxial electric cable for mobile communication and method for manufacturing

Abstract: The invention relates to the improvement of a RF coaxial cable which is used for mobile communication. The invention is characterized in that the wall thickness of the inner conductor of a copper tube is 0.1-0.25mm, and the inner conductor of the copper tube has a filling supporting body. The cable of the invention not only can retain the electrical property of the coaxial cable of the original thick conductor, but also can greatly reduce the copper use amount of the inner conductor; the coaxial cable with the same specification can save 40-60% of copper used by the inner conductor, can make up the cost increase which is brought by the price rise of copper, and also reduces the cable weight; in addition, as the supporting body is increased in the inner conductor tube, the deficiency of lowered pressure resistance of the copper tube which is caused by the wall thickness decrease of the copper tube can be made up, and the mechanical property of cable is ensured. Take the 1 km 7/8'' cable for example, the copper consumption cost of the inner conductor can be reduced by RMB 4940, and the total cable weight is reduced to 422.5 kilograms from 471 kilograms. In addition, the wall thickness of the copper tube is reduced, so the inner conductor tube can be changed by copper belt longitudinal package welding molding, and the cost of the copper tube is further lowered. Besides, as the wall thickness of the inner conductor copper tube is reduced and a foaming supporting body is used, the softness of the cable is improved; taking the 7/8'' cable for an example, the bend radius once can be reduced about 40%.

How small can a microring resonator be and yet be polarization independent

Abstract: There has been a recent trend to reduce the size of photonic waveguide devices to enable high-density integration in silicon photonic integrated circuits. However, this miniaturization tends to result in increased polarization dependency. Particularly challenging is designing devices based on ring waveguides with small radii, which exacerbates the polarization sensitivity. For these microring resonators, a legitimate question is then: Is it possible to simultaneously maintain the conditions of single-mode and structural polarization independence while shrinking the size of both the bend radius and the waveguide cross section, and, if so, how small can the ring resonator be? We demonstrate theoretically the feasibility of achieving this via deeply etched submicrometer silicon-on-insulator rib waveguides, and we show that, for a given cladding and core thickness, the radius of a polarization independent microring resonator can be as small as 3 microm, being limited chiefly by the residual birefringence of the resonator cavity and the bend losses.

Small Bend Structures Using Trenches Filled With Low-Refractive Index Material for Miniaturizing Silica Planar Lightwave Circuits

Abstract: We have proposed the fabrication of small bend structures using trenches along both sides of the core, filled with low-refractive index material, in order to miniaturise silica planar lightwave circuits. The minimum bending radius of a silica waveguide was reduced from 2 mm to 200 mum by filling the trenches with low-refractive index material. The local lateral relative refractive index difference (Delta) was increased to 8.64%. We fabricated cascade S-shaped waveguides to estimate a bend loss of the proposed structure. Moreover, we applied those structures to arrayed-waveguide gratings (AWG)s. Both 8-channel, 100-GHz channel-spacing and 8-channel, 12.5-GHz channel-spacing AWGs were successfully fabricated. Compared with conventional AWGs, sizes of these devices were reduced by factors of about 2 and 4, respectively.

Cabinet fiber manager

Abstract: An apparatus for storing and routing a fiber optic cable to an equipment cabinet is described. The apparatus includes a storage tray having a planar surface for accommodating the fiber optic cable. The tray is mounted to an upper end of the equipment cabinet. The tray has a plurality of routing channels extending along the planar surface and a portion thereof extending along at least one surface of the equipment cabinet generally perpendicular to the planar surface, with each of the routing channels defining a minimum bend radius to restrict over bending of the fiber optic cable. The tray has a central portion for accommodating the fiber optic cable, and the plurality of routing channels are in communication with the central portion and extending downward towards equipment supported by the equipment cabinet.

Cable routing assembly including protective cable frame

Abstract: A cable routing assembly for providing a portal for routing low voltage cables through a wall. The cable routing assembly includes a protective cable frame, a low voltage mounting bracket, and a cover plate. The low voltage mounting bracket includes two adjustable flags for attachment to a wall. The protective cable frame includes two arms with apertures therein to enable mounting directly to the low voltage mounting bracket. Bores in the arms of the protective cable frame enable receipt of fasteners for mounting the cover plate thereto. An opening in the protective cable frame is capable of receiving low voltage cables for routing through the wall and into an adjacent room. The surface of the cable frame opening includes a rounded surface to provide a gentle bend radius to any cables routed through the cable frame.