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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 20, Issue 3, 2 February 1984

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Volume 20, Issue 3

2 February 1984

Core alignment procedure for single-mode-fibre jointing
  • Author(s): C.M. de Blok  and  P. Matthijsse
  • Source: Electronics Letters, Volume 20, Issue 3, p. 109 –110
  • DOI:  10.1049/el:19840074
  • Type: Article
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  • p. 109 –110 (2)
    An auxiliary optical system is described which will enable the core alignment of single-mode fibres in a jointing location without use of far-end apparatus. The system is based on the launching of an optical signal into the core of the first fibre and the detection of this signal from the core of the second fibre by bending of the fibres and without removal of the coating. A two-step experimental alignment procedure is described consisting of a visual coarse alignment followed by a fine alignment by means of a simple piezo-electric fibre translator.
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Video transmission over cabled monomode fibre at 1.523 μm using PFM with 2-PSK heterodyne detection
Birefringence calculations in elliptical-core optical fibres
Scanning acoustic interference microscope with wedge delay line
  • Author(s): N. Chubachi  and  H. Okazaki
  • Source: Electronics Letters, Volume 20, Issue 3, p. 113 –115
  • DOI:  10.1049/el:19840077
  • Type: Article
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  • p. 113 –115 (3)
    The variable acoustic delay line employing a wedge can be successfully introduced to accomplish a novel interference microscope. This interference microscope can be easily established only by substituting a wedge for the specimen mount in the conventional scanning acoustic microscope. The acoustic velocity of as-sputtered ZnO film is measured with this microscope at a frequency of 150 MHz. The acoustic velocity of a longitudinal wave along the c-axis in the ZnO film is determined to be 6.3 km/s.
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Dopant effect on transmission loss increase due to hydrogen permeation
Analysis of a microstrip dipole antenna
Loss spectra of optical fibres under hydrogen and deuterium
  • Author(s): K. Mochizuki ; Y. Namihira ; M. Kuwazuru ; M. Nunokawa ; Y. Iwamoto
  • Source: Electronics Letters, Volume 20, Issue 3, p. 118 –119
  • DOI:  10.1049/el:19840080
  • Type: Article
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  • p. 118 –119 (2)
    Assignment of the frequencies at the loss peaks due to hydrogen permeation is clarified on the basis of the loss spectra in silica glass fibre under deuterium. As a result, it is concluded that the loss peaks due to hydrogen permeation in silica glass fibre are related to the combinational vibrations of hydrogen molecular vibration and SiO4 tetrahedral vibrations.
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Measurement of spatial distributions of mode coupling in polarisation-maintaining fibres
Dynamic linewidth of amplitude-modulated single-longitudinal-mode semiconductor lasers operating at 1.5 μm wavelength
  • Author(s): N.A. Olsson ; N.K. Dutta ; K.-Y. Liou
  • Source: Electronics Letters, Volume 20, Issue 3, p. 121 –122
  • DOI:  10.1049/el:19840082
  • Type: Article
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  • p. 121 –122 (2)
    We have measured the frequency chirp characteristics of single-longitudinal-mode semiconductor lasers operating at 1.5 μm wavelength and subject to large signal amplitude modulation in the 50 to 800 MHz range. Measurements on cleaved-coupled-cavity (C3) and GRIN-rod external cavity lasers show that the wavelength chirp is large enough to cause a penalty in ultra-high-bit-rate long-haul optical-fibre systems.
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The problem of a conducting sphere resting on an earthed plane in a uniform perpendicular field and its applications
Halogen lamp annealing of GaAs for MESFET fabrication
  • Author(s): M.H. Badawi  and  J. Mun
  • Source: Electronics Letters, Volume 20, Issue 3, p. 125 –126
  • DOI:  10.1049/el:19840084
  • Type: Article
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  • p. 125 –126 (2)
    Incoherent light from high-intensity halogen lamps was used for capless annealing of 2-inch GaAs wafers following silicon ion implantation. Fabrication of depletion mode MESFETs on the annealed wafers was used to study the DC characteristics and uniformity achieved with this annealing method. An average mutual transconductance of 110 mS/mm was obtained with MESFET fabricated wafers which were uniformly implanted at 5 × 1012 cm−2 with Si+ at 80 keV and subsequently annealed at 900°C for 2 s. The carrier concentration profiles obtained with this method are shown to be sharper than those obtained with furnace annealed wafers, which in turn results in a sharper device pinch-off voltage.
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Sidelobe reduction for a microstrip travelling-wave antenna array using partially random weighting
  • Author(s): W.L. Wang  and  M.S. Smith
  • Source: Electronics Letters, Volume 20, Issue 3, p. 126 –128
  • DOI:  10.1049/el:19840085
  • Type: Article
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  • p. 126 –128 (3)
    The sidelobe performance of a microstrip travelling-wave antenna array is limited by the crosspolarised lobes produced if a comb-line is used with a large range of stub widths.1.2 The amplitude taper which can be applied is thereby limited to ≃6–7.5 dB, so that very low sidelobes (< −30 dB) cannot readily be achieved. Here a technique is described which offers copolar sidelobe reduction without excessive crosspolarisation, with calculated sidelobes <30 dB for a 32-element array. An amplitude taper of 20 dB is achieved using a split comb-line (giving 12–15 dB taper) plus partially random weighting.
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Single-mode transmission selective integrated-optical polarisers in LiNbO3
Fibre-optic cable for CO laser power transmission
  • Author(s): E.M. Dianov ; V.J. Masychev ; V.G. Plotnichenko ; V.K. Sysoev ; P.J. Baikalov ; G.G. Devjatykh ; A.S. Konov ; J.V. Schipachev ; M.F. Churbanov
  • Source: Electronics Letters, Volume 20, Issue 3, p. 129 –130
  • DOI:  10.1049/el:19840087
  • Type: Article
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  • p. 129 –130 (2)
    The description of the experimental fibre-optic cable on the base of chalcogenide glass IR fibre, which can be used for medical and technological purposes, is cited in the letter. The cable length is 1–1.5 m, the fibre diameter is 0.5–0.8 mm and the total cable diameter is 10 mm. The transmission of 7 W continuous CO laser radiation power for a few hours is realised through the cable.
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Increasing IATO in TIL GTO thyristors
14 Gbit/s optical signal encoding for λ = 1.32 μm with double pulse drive of a Ti:LiNbO3 waveguide modulator
Effect of processor perturbations on an adaptive beamformer
Multi-combline warped-mode directional couplers
  • Author(s): B.A. Herscher  and  J.E. Carroll
  • Source: Electronics Letters, Volume 20, Issue 3, p. 134 –136
  • DOI:  10.1049/el:19840091
  • Type: Article
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  • p. 134 –136 (3)
    A first report of multi-combline warped-mode directional couplers using three lines is presented. The technique outlined can be extended to many different designs and additional lines. The specific example given has been designed as a 3-way equal power splitter with a phase difference of 180° and 0° between the two outer lines and the central line. The coupler is fed from the central line at the input. The device exhibits significant coupling over the range 0.7 to 9 GHz, but with ripples at the lower frequencies and loss at the higher frequencies the most useful range is about 3 to 8 GHz.
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Dual-mode optical-fibre interferometric sensor
  • Author(s): J.L. McMillan  and  S.C. Robertson
  • Source: Electronics Letters, Volume 20, Issue 3, p. 136 –137
  • DOI:  10.1049/el:19840092
  • Type: Article
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  • p. 136 –137 (2)
    The letter describes how a dual-mode optical fibre can be used as an interferometric temperature sensor either by fringe counting or, more importantly, by analysis of the change in chromatic transmission spectrum with temperature. Such a sensor has the geometric flexibility of an all-fibre interferometric sensor as well as the advantages of a wavelength modulating device, i.e. high accuracy, noise immunity, absolute measurement capability and no need for intensity calibration.
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Chip area estimation method for VLSI chip floor plan
Temperature regulator for irradiation systems designed for evaluation of microwave bioeffects
Chemical change from diffused hydrogen gas to hydroxyl ion in silica glass optical fibres
  • Author(s): H. Itoh ; Y. Ohmori ; M. Nakahara
  • Source: Electronics Letters, Volume 20, Issue 3, p. 140 –142
  • DOI:  10.1049/el:19840095
  • Type: Article
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  • p. 140 –142 (3)
    The chemical change from hydrogen gas that diffuses into silica glass for optical fibres to hydroxyl function has been investigated. Hydrogen molecules that diffuse into GeO2-doped silica glass at 500°C easily change into OH ions by thermal energy, while this chemical change does not occur in pure silica glass at 500°C. Also, germanium-doped silica fibre, in which hydrogen gas is dissolved at room temperature, shows OH ion absorption loss increase with chemical change by heat treatment at above 100°C, while pure silica core fibre shows no OH ion absorption loss increase by the same treatment.
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Evidence of bandgap-narrowing in the space-charge layer of heavily doped silicon diodes
  • Author(s): J.R. Lowney  and  W.R. Thurber
  • Source: Electronics Letters, Volume 20, Issue 3, p. 142 –143
  • DOI:  10.1049/el:19840096
  • Type: Article
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  • p. 142 –143 (2)
    The gradient voltage has been measured for seven heavily doped, graded-junction silicon diodes at 300 K. Experimental values up to nearly 0.5 V lower than conventional theoretical predictions have been observed. The lowering is attributed to bandgap-narrowing in the space-charge region. This narrowing is expected to be much larger than in neutral material of the same doping density because of the absence of free-carrier screening.
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Physical interpretation of Petermann's strange spot size for single-mode fibres
Vertical electron transistor (VET) in GaAs with a heterojunction (AlGaAs-GaAs) cathode

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