Losses In Tapes Research Articles

Low-loss C-band all-fiber FIFO device by novel bridge fiber

Multi-core fibers (MCF) technology is the feasible path to extend the capacity of optical fiber communication systems. However, there is a lack of low-loss and low-crosstalk multi-core fan-in and fan-out (FIFO) devices for MCF communication in the C-band. In this paper, we proposed all-fiber FIFO devices with seven trench-assisted bridge fibers (TABFs). The special structure of the TABFs could facilitate the matching of single-core fiber with MCF during the tapering progress. By using the TABFs, the average taper loss was less than 0.06 dB. The novel method can reduce the insertion loss of FIFO devices. The experiments indicated that the fabricated FIFO devices exhibited lower than 0.50 dB insertion loss and less than −55.2 dB crosstalk in the C-band. This work provides novel TABFs and an efficient way to fabricate low-loss low-crosstalk FIFO devices for MCF communication systems.

Myosin VI Haploinsufficiency Reduced Hearing Ability in Mice

In human, myosin VI (MYO6) haploinsufficiency causes postlingual progressive hearing loss. Because the usefulness of mouse models remains unclear, we produced novel Myo6 null (−/−) mutant mice and analyzed the hearing phenotypes of Myo6+/− (+/−) heterozygous mutants. We first recorded and compared the auditory brainstem responses and distortion product otoacoustic emissions in control Myo6+/+ (+/+) wild-type and +/− mice. These hearing phenotypes of +/− mice were mild; however, we confirmed that +/− mice developed progressive hearing loss. In particular, the hearing loss of female +/− mice progressed faster than that of male +/− mice. The stereocilia bundles of +/− mice exhibited progressive taper loss in cochlear inner hair cells (IHCs) and outer hair cells (OHCs). The loss of OHCs in +/− heterozygotes occurred at an earlier age than in +/+ mice. In particular, the OHCs at the basal area of the cochlea were decreased in +/− mice. IHC ribbon synapses from the area at the base of the cochlea were significantly reduced in +/− mice. Thus, our study indicated that MYO6 haploinsufficiency affected the detection of sounds in mice, and we suggest that +/− mice with Myo6 null alleles are useful animal models for gene therapy and drug treatment in patients with progressive hearing loss due to MYO6 haploinsufficiency.

Intelligent Surface-Aided Transmitter Architectures for Millimeter-Wave Ultra Massive MIMO Systems

In this paper, we study two novel massive multiple-input multiple-output (MIMO) transmitter architectures for millimeter wave (mmWave) communications which comprise few active antennas, each equipped with a dedicated radio frequency (RF) chain, that illuminate a nearby large intelligent reflecting/transmitting surface (IRS/ITS). The IRS (ITS) consists of a large number of low-cost and energy-efficient passive antenna elements which are able to reflect (transmit) a phase-shifted version of the incident electromagnetic field. Similar to lens array (LA) antennas, IRS/ITS-aided antenna architectures are energy efficient due to the almost lossless over-the-air connection between the active antennas and the intelligent surface. However, unlike for LA antennas, for which the number of active antennas has to linearly grow with the number of passive elements (i.e., the lens aperture) due to the non-reconfigurablility (i.e., non-intelligence) of the lens, for IRS/ITS-aided antennas, the reconfigurablility of the IRS/ITS facilitates scaling up the number of radiating passive elements without increasing the number of costly and bulky active antennas. We show that the constraints that the precoders for IRS/ITS-aided antennas have to meet differ from those of conventional MIMO architectures. Taking these constraints into account and exploiting the sparsity of mmWave channels, we design two efficient precoders; one based on maximizing the mutual information and one based on approximating the optimal unconstrained fully digital (FD) precoder via the orthogonal matching pursuit algorithm. Furthermore, we develop a power consumption model for IRS/ITS-aided antennas that takes into account the impacts of the IRS/ITS imperfections, namely the spillover loss, taper loss, aperture loss, and phase shifter loss.

Efficient TE/TM spot-size converter for broadband coupling to single mode fibers

We present the novel design of a spot-size converter (SSC) for high efficiency coupling between a conventional single-mode fiber (SMF) and a standard silicon nanowire. Our design involves evanescent coupling between a stack of Si3N4/SiO2 alternating layers and a standard silicon nanowire. The proposed SSC coupler demonstrates highly broadband performance with a polarization dependence of less than 0.62 dB and an expected taper loss of less than 1.0 dB, over 100 nm bandwidth ranging from 1.5 to 1.6 µm. To the best of our knowledge, the proposed SSC achieves the highest broadband coupling for both polarizations between a fiber with a large mode-field diameter (i.e., SMF-28) and a standard silicon nanowire.

Retrieval Analysis And Principal Variable Analysis Of 127 M2a-38 Mm™ Metal On Metal Hip Replacements

BackgroundThe objective of this study was to investigate the factors which affected the material loss from 127 M2a-38 mm™ hip replacements. MethodsThe alignment and patient data was obtained for 127 patients. The explants bearings and tapers were measured to determine the level of material loss and their geometry. Results87 joints were edge wearing (EW), 28 normally wearing (NW) and 12 had edge interaction (EI). The NW joints were wearing at a mean bearing combined rate of 0.34 mm3/yr. For the NW joints, bearing clearance was linked to the bearing combined volumetric loss rate (r = 0.446). The rates of loss from the head's taper was 0.21 mm3/yr. Lower wearing and lower clearance joints had higher values of loss from the tapers. The taper loss from joints with a positive clearance were significantly higher (p = .026) than those with a negative clearance. ConclusionsThe results demonstrate that bearing loss rates for NW joints was as expected. The high number of joints showing signs of edge wearing resulted from low clearances and a low cup articular arc angle. The taper loss was lower than other similar joint designs with positive clearances resulting in greater loss.

Side Lobe Suppression and Gain Retaining of Practical Space-Borne Active Phased Antenna Array With Triangular Grids

In a practical space-borne active phased antenna array (APAA), main beam scanning angle (MBSA)-dependent low side lobe level (SLL) and taper loss are the ultimate and most critical performances. At some MBSA, extremely SLL in some local space is needed. The harsh limitation on APAA taper loss further complicates the problem seriously. In this paper, the main beam scanning space (MBSS) was divided into several subspaces. Instead of applying a single set of weights regardless of the MBSA, a separate set of weights is implemented independently in each subspace. This transforms the nearly unsolvable problem into multiple solvable problems. An array-decomposition approach is proposed to further reduce the number of synthesis parameters for each subspace. The entire array is simplified as an assembly of multiple sub-arrays. Each and every sub-array shares the same set of weights. The number of synthesis parameters is therefore reduced to the order of the subarray that the synthesis is much easier to solve without sacrificing too much synthesis performance. The proposed approach has been applied to solve concerned practical problem successfully.

Comparative study of material loss at the taper interface in retrieved metal-on-polyethylene and metal-on-metal femoral components from a single manufacturer

There have been a number of reports on the occurrence of taper corrosion and/or fretting and some have speculated on a link to the occurrence of adverse local tissue reaction specifically in relation to total hip replacement which have a metal-on-metal bearing. As such a study was carried out to compare the magnitude of material loss at the taper in a series of retrieved femoral heads used in metal-on-polyethylene bearings with that in a series of retrieved heads used in metal-on-metal bearings. A total of 36 metal-on-polyethylene and 21 metal-on-metal femoral components were included in the study all of which were received from a customer complaint database. Furthermore, a total of nine as-manufactured femoral components were included to provide a baseline for characterisation. All taper surfaces were assessed using an established corrosion scoring method and measurements were taken of the female taper surface using a contact profilometry. In the case of metal-on-metal components, the bearing wear was also assessed using coordinate metrology to determine whether or not there was a relationship between bearing and taper material loss in these cases. The study found that in this cohort the median value of metal-on-polyethylene taper loss was 1.25 mm3 with the consequent median value for metal-on-metal taper loss being 1.75 mm3. This study also suggests that manufacturing form can result in an apparent loss of material from the taper surface determined to have a median value of 0.59 mm3. Therefore, it is clear that form variability is a significant confounding factor in the measurement of material loss from the tapers of femoral heads retrieved following revision surgery.

Heterogeneous lasers and coupling to Si₃N₄ near 1060 nm.

A III-V/Si₃N₄ platform on silicon is presented capable of broad-spectral performance with initial heterogeneous lasers near 1060 nm. Continuous wave Fabry-Perot laser results for heterogeneous InGaAs/GaAs multiple quantum well (MQW) laser with output power approaching 0.25 mW on Si is demonstrated. Taper transmission loss measurements from III-V to Si₃N₄ are measured to be 2.5±0.75 dB.

Characterization of Insertion Loss and Back Reflection in Passive Hybrid Silicon Tapers

The optical properties of two hybrid silicon taper designs are investigated. These tapers convert the optical mode from a silicon waveguide to a hybrid silicon III/V waveguide. A passive chip was fabricated with an epitaxial layer similar to those used in hybrid silicon lasers. To separate optical scattering and mode mismatch from quantum-well absorption, the active layer in this paper was designed to be at 1410 nm, to allow measurements at 1550 nm. Using cutback structures, the taper loss and the taper reflection are quantified. Taper losses between 0.2 and 0.6 dB per taper and reflections below -41 dB are measured.

SU8 3D prisms with ultra small inclined angle for low-insertion-loss fiber/waveguide interconnection

This paper presents a simple method for fabricating SU8 three dimensional (3D) prisms with very small inclined-angles for optical-fiber/planar-waveguide interconnection with low insertion-loss by combining self-filling, molding and nano-lithography processes on plane surface. The prisms possess ultra low 3D inclined angle of 0.6° and a small surface roughness of 3.5 nm. It is demonstrated that the transmission efficiency of SOI waveguides improved about 4.6 times at the presence of SU8 prisms with a coupling loss of 11 dB per taper and radiation loss of 2.4 dB per taper.

Tapered silicon optical fibers

The tapering of silicon optical fibers is demonstrated using a fusion splicer. The silicon fibers are fabricated using a high pressure chemical deposition technique to deposit an amorphous silicon core inside a silica capillary and the tapering is performed in a separate post-process. Optical and material characterization has revealed a smooth transition region leading to a uniform tapered waist that are both simultaneously crystallized to yield a solid polysilicon core. The strong mode confinement and low taper loss measured in the silicon fibers verifies this tapering approach for the fabrication of structures with nanoscale core dimensions.

Effect of the Stack in HTS Tapes Exposed to External Magnetic Field

For large power applications, such as, HTS transformer, HTS motor and HTS power cable, stacked HTS tapes should be used because single HTS tape is limited in flowing of demanded current. Besides, insulation between layers is need for safe operation because high voltages are applied in those applications. The stacked HTS tapes have different characteristics compared with the single HTS tape because of screening effect. In this paper, we measured the magnetization losses in stacked HTS tapes of several samples having the various insulation thickness and various packing numbers of tape at 77 K. Properties of three different types of the stacks which consisted of 2, 3, and 4 tapes were measured and compared with that of single HTS tape. Also, numerical calculation by finite element method was done to compare with experimented data. Perpendicular magnetic fields were applied to the HTS stacks as external magnetic field. Results of measurement and calculation showed that magnetization loss of a stacked tape divided by stacking number of tape was smaller than the single tape's loss. This tendency was distinct as the distance between the tapes became closer and stacking number of tapes increased.

AC Transport Current Loss of Horizontally Attached Bi-2223/Ag Tapes

In this paper we investigate AC-transport current loss and current distribution of Bi-2223/Ag tapes which are arranged in edge-to-edge configuration. A numerical code was developed to estimate the transport current loss and the current distribution across the tapes. AC-loss measurements were also performed and the coincidence between the calculated and measured values is excellent. AC losses of the horizontally-attached tapes were larger than just a simple summation of each tape's loss but not as large as the loss from Norris equation. Discussions on these results are addressed using the current distribution obtained from numerical analysis.

Wide-scan spherical-lens antennas for automotive radars

A new approach to wide scan-angle antennas at millimeter-wave frequencies is introduced with special focus on ease of manufacturing and reliability. The system is composed of planar feed antennas (tapered-slot antennas), which are positioned around a homogeneous spherical Teflon lens. Beam scanning can be achieved by switching between the antenna elements. The spherical-lens system is analyzed through a combined ray-optics/diffraction method. It is found that a maximum efficiency of 50%-55% can be achieved using Teflon, Rexolite, or quartz lenses. The efficiency includes taper, spillover, and reflection loss. Calculations also indicate that the maximum lens diameter is 30-40 /spl lambda//sub 0/, which results in a maximum directivity of 39.5-42 dB. Measurements done on a single-element feed and a 5-cm Teflon lens agree very well with theory and result in a 3-dB beamwidth of 5.5/spl deg/ and better than -20-dB sidelobe levels at 77 GHz. Absolute gain measurements show a system efficiency of 46%-48% (including dielectric loss). A 23- and 33-element antenna array with a scan angle of /spl plusmn/90/spl deg/ and a -3.5- and -6-dB crossover, respectively, in the far-field patterns was also demonstrated. The 23-element array resulted in virtually no gain loss over the entire 90/spl deg/ scan angle. This represents, to our knowledge, the first wide scan-angle antenna at millimeter-wave frequencies.

1.3-μm large spot size laser for efficient fiber coupling

Taper and truncation loss calculations, experimental internal reflections, and far-field characteristics and coupling efficiencies into single-mode fiber are reported for a 1.3-?m large spot laser design with laterally tapered active region and a weakly guiding passive waveguide underneath. In the front passive section, the taper is truncated. Modeled taper loss and truncation loss at the end of the taper are compared. It is shown that for taper lengths exceeding 125 ?m, truncation loss dominates taper loss unless the truncated active width is smaller than ~ 0.2 mm. Reflectometer experiments show that for a truncated active width of 0.2 ?m, reflections at the truncation point are negligible, in agreement with modeling results. Experimental far fields are shown to become narrower and smoother as the taper length or the passive section length is increased. Coupling efficiencies into a single-mode fiber are reported. Up to 56% butt-coupling is achieved, with 1 dB lateral fiber positional tolerance of up to 2.4 ?m horizontally and 2.3 ?m vertically.

Dynamic etch mask technique for fabricating tapered semiconductor optical waveguides and other structures

Using a novel dynamic etch mask technique and wet chemical etchants, we have produced semiconductor structures with tapered thicknesses, with horizontal slope angles as small as 0.9°. With this technique we have fabricated GaAs/GaAlAs rib optical waveguides in which the etch depth tapered from 0.2 to 1.0 μm over a distance of 50 μm, resulting in a 2× change in mode size, with an excess taper loss of less than 0.2 dB. The technique is capable of producing tapers in different orientations, at arbitrary locations on a sample, and appears to be useful for a wide variety of materials systems and devices.

Taper splice method for single-mode fibers

A low-loss splice method which processes a splice point to a taper shape is investigated for use in subscriber single-mode fiber cables. An average splice loss, taking into account the fiber parameter deviations and radiation loss in the taper portion, is estimated statistically and experimentally. The optimum value of the taper ratio is determined to be 0.55. A new processing method for gradual tapers, by pulling fibers and moving a pair of discharged electrodes, is presented. It is clear that radiation loss due to waveguide metamorphosis is the dominant cause of taper loss, which is influenced by fiber structures. It is also clear that the quick fusion method, with a discharge duration of 1 s, is desirable for the taper splice method. Furthermore, it is confirmed that for splicing two fibers having core eccentricities of 1.5 and ≃0 μm, splice loss can be improved from 0.4 to 0.25 dB by processing the splice point to a taper shape.

Analysis of single-mode fused tapered fibre couplers

A fabrication technique for fused taper couplers is described. Coupling coefficients are calculated for fibres with raised, depressed and matched refractive-index profiles, and optimum V-values for coupling are found. These suggest a shorter coupler geometry differing from the biconical taper. The high taper loss in depressed cladding fibres is shown to correspond to the presence of the leaky LP01-mode. The wavelength response has been measured for various couplers and fitted theoretically. Coupling periods as small as 12 nm demonstrate potential use for couplers as wavelength-division multiplexers. The dependence of coupling on the refractive index of the surrounding medium has been measured. Thus couplers have also demonstrated potential as temperature sensors and optical switches.

Measurement and utilization of in vivo blood-pressure transfer functions of dog and chicken aortas.

A method for determining the essential parameters of the aorta, namely the geometric taper, area, hoop elasticity, and effective loss factor, from in vivo pressure measurements is presented. A nonuniform hybrid model, having both geometric and elastic taper and terminated in a reflectionless impedance at the femoral bifurcation, is utilized.