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image of Volume 22, Issue 20
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 22, Issue 20, 25 September 1986

Volumes & issues:

Volume 22, Issue 20

25 September 1986

Security of Okamoto public-key cryptosystem
Transmission loss characteristics of fluoride glass single-mode fibre
  • Author(s): Y. Ohishi ; S. Sakaguchi ; S. Takahashi
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1034 –1035
  • DOI:  10.1049/el:19860709
  • Type: Article
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  • p. 1034 –1035 (2)
    The transmission loss spectrum of a fluoride glass single-mode fibre as obtained with a new preform fabrication technique is shown. It is clearly confirmed on the loss spectrum that the obtained fibre is a single-mode waveguide in the minimum loss wavelength range (2–4 μm). The minimum loss of this fibre is 8.5 dB/km at 2.2 μm and the OH excess loss is 15dB/km at 2.85 μm. This fabrication technique is effective in eliminating OH contamination.
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Method for traffic and blocking estimation from test-calling measurements
  • Author(s): M. Koukias  and  G. Kokkinakis
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1035 –1037
  • DOI:  10.1049/el:19860710
  • Type: Article
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  • p. 1035 –1037 (3)
    A method for the estimation of real traffic offered to a trunk from the congestion loss measured with a test-call generator is described. The method consists in simulating both kinds of traffic (real and artificial) and in extracting a relation between the above quantities. Simulations were made for several offered traffic models and test calling rates and led to the construction of tables and diagrams for practical use.
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Flicker noise in GaAs MESFET X-band amplifiers in the temperature range 300 K to 2 K
  • Author(s): L.D. Mann ; D.G. Blair ; K.J. Wellington
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1037 –1038
  • DOI:  10.1049/el:19860711
  • Type: Article
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  • p. 1037 –1038 (2)
    We report measurements of the noise temperature of small-signal, low-noise X-band GaAs MESFET amplifiers from room temperature down to 2 K, at offset frequencies of several hundred hertz from the carrier and for input carrier powers from -40 to -20dBm. We observe a dramatic increase in the level of flicker noise as these devices are cooled to liquid helium temperatures, in marked contrast to the normally observed decrease in noise temperature of an unsaturated GaAs MESFET amplifier as it is cooled.
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Two-dimensional index distribution determination from near-field measurements in single-mode fibres
Dichroic dual-band microstrip array
  • Author(s): J.R. James  and  G. Andrasic
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1040 –1042
  • DOI:  10.1049/el:19860713
  • Type: Article
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  • p. 1040 –1042 (3)
    It is demonstrated that two microstrip arrays can be superimposed in a common planar aperture to create a dual-band array. The concept relies critically on the invisibility of the uppermost array, which is constructed from a frequency-selective conducting surface (FSCS). Analysis and measurements establish the degree of invisibility obtainable in an FSCS of finite extent and indicate the likely behaviour in a composite system. Measurements for a dual-band array illustrate the findings and good future prospects for the concept, but also show that feeder line radiation, if not reduced, can constrain sidelobe levels.
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Antenna power pattern synthesis using method of successive projections
Power penalty due to decision-time jitter in receivers using avalanche photodiodes
  • Author(s): T.M. Shen
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1043 –1045
  • DOI:  10.1049/el:19860715
  • Type: Article
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  • p. 1043 –1045 (3)
    Power penalties on receiver sensitivity due to the presence of timing jitter are derived for receivers incorporated with PIN detectors and with avalanche photodiodes. It is shown that the presence of timing jitter will lower the optical gain of the avalanche photodiodes and will reduce the improvement in receiver sensitivity of using avalanche photodiodes over PIN detectors. Using computer simulation on results of transmission experiments it is shown that the receiver sensitivity can be degraded by several decibels owing to the presence of timing jitter in the Anritsu pulse pattern generator and/or error detector.
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Compact bulk optical isolator with monomode fibre pigtails for use at 1.3 μm
Complexity and autocorrelation properties of a class of de Bruijn sequences
Design of DFB lasers for high-power single-mode operation
Solution to some electromagnetic problems using fast Fourier transform with conjugate gradient method
Dispersion-determined limits on production tolerances of single-mode fibres
Measurement of direct frequency modulation characteristics of DFB-LD by delayed self-homodyne technique
  • Author(s): S. Ryu  and  S. Yamamoto
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1052 –1054
  • DOI:  10.1049/el:19860721
  • Type: Article
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  • p. 1052 –1054 (3)
    The direct frequency modulation characteristics of a DFB-LD can be simply measured by means of a delayed selfhomodyne method using a single-mode fibre delay line and a single-mode fibre coupler. This measuring method has the features of simple set-up and high resolution when narrow-linewidth optical sources are used, compared to the conventional interferometric methods. Direct frequency modulation characteristics of a DFB-LD in the 1.55 μm region are measured, and the results obtained agree well with those by a Fabry-Perot interferometer.
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Planim: a new concept in the design of MIC filters
  • Author(s): M. Salerno  and  R. Sorrentino
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1054 –1056
  • DOI:  10.1049/el:19860722
  • Type: Article
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  • p. 1054 –1056 (3)
    The planar circuit approach for the characterisation of microstrip circuits is combined with the image parameter method to give a new powerful technique for integrated circuit filter design (planim). The inclusion of two-dimensional effects in the synthesis procedure makes the planim approach particularly suited for monolithic microwave circuits. The design of microstrip filters with extremely wide stopbands is shown as an example.
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MOS SC microsystem for generating trigonometrical functions and their inverses
  • Author(s): A. Cichocki  and  R. Unbehauen
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1056 –1057
  • DOI:  10.1049/el:19860723
  • Type: Article
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  • p. 1056 –1057 (2)
    A new switched-capacitor (SC) circuit arrangement is proposed for the simultaneous generation of trigonometrical functions (sin x, cos x, tan x) and their inverses (sin-1x, cos-1x, tan-1x) in analogue form, where x(t) is the input voltage. The method is based on the sample-and-hold and time-division principles. The system possesses some attractive features, e.g. simplicity and low cost, and can be easily implemented in monolithic (IC) form using MOS technology. The performance of the system is illustrated by experimental results.
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High-performance millimetre-wave suspended stripline Gunn VCO
Feed design for a two-dimensional bootlace lens
Coherent phase-locked synchronous oscillator
  • Author(s): V. Uzunoglu
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1060 –1061
  • DOI:  10.1049/el:19860726
  • Type: Article
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  • p. 1060 –1061 (2)
    A coherent phase-locked synchronous oscillator (CPSO) is a coherent synchronisation and tracking network developed using a synchronous oscillator and a feedback network, external to the synchronous oscillator (SO). It is a unique network whose noise bandwidth is fully independent of its tracking range and has absolute coherency throughout the tracking range. It has several orders of magnitude wider tracking range for a given input signal/noise ratio than any other tracking network.
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Method to reduce the sign bit extension in a multiplier that uses the modified Booth algorithm
Mechanism of carrier lifetime increase in ion beam synthesised SOI structures
  • Author(s): W. Skorupa ; H. Oertel ; H. Bartsch
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1062 –1064
  • DOI:  10.1049/el:19860728
  • Type: Article
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  • p. 1062 –1064 (3)
    Carrier lifetimes were measured in epitaxial silicon layers which were deposited on silicon wafers implanted with different nitrogen doses at 330 keV. At doses greater than 1016 cm-2 the lifetime was more than one order of magnitude higher on the implanted part of the wafers (∼300μs). The mechanism responsible for this effect is connected with the gettering efficiency for heavy metals of a precipitation-rich dislocation network in the implanted silicon.
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Compact broadband microstrip antenna
Nondispersive delay line at microwave frequency by magnetostatic forward volume waves
Optical waveguides in In0.52Al0.48As grown on InP by MBE
Direct electro-optic sampling of a GaAs integrated circuit using a gain-switched InGaAsP injection laser
Simple formula for estimation of minimum clock-feedthrough error voltage
Novel trial field of single-mode graded-index fibres usable for non-Gaussian field distributions
  • Author(s): K. Hayata ; M. Koshiba ; M. Suzuki
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1070 –1072
  • DOI:  10.1049/el:19860734
  • Type: Article
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  • p. 1070 –1072 (3)
    A novel trial field for the variational analysis of the fundamental mode of graded-index optical fibres is proposed, which is usable for non-Gaussian field distributions and is compatible with our physical intuition. A comparison is made with results obtained using the conventional Gaussian trial field and those of a rigorous numerical method. As a result, the present method can yield satisfactorily accurate results even in the region where the conventional method fails to be applied, without involving much computational effort.
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Calculation of bit error rate in ASK heterodyne systems with envelope detection influenced by laser phase noise
Random test length with and without replacement
  • Author(s): W.H. Debany ; P.K. Varshney ; C.R.P. Hartmann
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1074 –1075
  • DOI:  10.1049/el:19860736
  • Type: Article
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  • p. 1074 –1075 (2)
    We compare the effectiveness of two methods of random test generation: with and without replacement of test patterns. Expressions for test length and test confidence for both methods are given. Determination of random test length is simpler when tests are generated with replacement, yet most practical random test methods produce tests without replacement. The conditions are obtained such that testing without replacement can be approximated using the simpler approach.
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Ultrahigh-strength fibre splices by modified H2/O2 flame fusion
  • Author(s): J.T. Krause
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1075 –1077
  • DOI:  10.1049/el:19860737
  • Type: Article
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  • p. 1075 –1077 (3)
    Although original fibre strength can be retained in fibre splices by fusing with an H2/O2 flame incorporating Cl2, there are often circumstances where the use of Cl2 is not always convenient or possible. The present effort to optimise splice strengths in the absence of Cl2 has resulted in average splice strengths of ∼690 ksi (∼4.8 GPa), values double those by conventional flame fusion or are fusion methods. This is of major advantage for all fusion splicing applications requiring high strength and long-term reliability.
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Adaptive correlation diversity for a CD900-like system in an urban mobile radio environment
Impact of coherence length on the amplitude variations of the delay power profile in a mobile environment
Linear imaging in scanning polarisation/interference contrast microscopy
  • Author(s): C.W. See  and  M. Vaez Iravani
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1079 –1081
  • DOI:  10.1049/el:19860740
  • Type: Article
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  • p. 1079 –1081 (3)
    The theory and design of a linear polarisation/interference contrast microscope are described. The operation of the technique is based on the use of a sinusoidally driven electro-optic phase modulator. The expected sensitivity of the system in detecting phase variations is 5 × 10-7 rad, in a 10Hz bandwidth. Experimental results are presented on the imaging of magnetic domains, which clearly demonstrate the sensitivity superiority of linear operation.
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High-power ridge-waveguide AlGaAs GRIN-SCH laser diode
  • Author(s): C. Harder ; P. Buchmann ; H. Meier
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1081 –1082
  • DOI:  10.1049/el:19860741
  • Type: Article
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  • p. 1081 –1082 (2)
    AlGaAs ridge single-quantum-well graded-index separate confinement heterostructure (SQW GRIN-SCH) lasers with typical threshold currents of 9 mA and differential quantum efficiencies between 80% and 85% for 0.4 mm-long cavities have been fabricated with molecular beam epitaxy. Continuous-wave light output increases linearly with the drive current up to approximately 15 times the threshold current. The lasers fail catastrophically at power levels between 65 mW/facet and 85 mW/facet, corresponding to power densities between 2.6 MW/cm2 and 3.4 MW/cm2.
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Large optical cavity (LOC) semiconductor laser arrays
  • Author(s): M. Jansen ; S.S. Ou ; J.J. Yang ; J. Wilcox ; M. Sergant ; L. Eaton ; W. Simmons
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1083 –1084
  • DOI:  10.1049/el:19860742
  • Type: Article
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  • p. 1083 –1084 (2)
    Schottky barrier and oxide-restricted ridge-waveguide large optical cavity (LOC) arrays were fabricated and tested. Both evanescently coupled and diffraction-coupled array geometries were evaluated in terms of lateral and transverse mode behaviour. The array stripes were 3 μm wide, with a separation of 4.5, 6, 7.5 and 9 μm from centre to centre. Peak powers of over 2W were obtained for 11-element devices, with typical threshold currents in the range of 20–25 mA/ stripe and differential quantum efficiencies of more than 60%. Single-lobe lateral far-field patterns were obtained for evanescently coupled arrays with a centre-to-centre stripe spacing of 4.5 μm and for diffraction-coupled arrays with a centre-to-centre stripe spacing of 6 μm and with 30 μm-long diffraction regions. The transverse-mode behaviour was investigated as a function of the guiding layer width.
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Narrowband tunable optical filter for channel selection in densely packed WDM systems
Parasitic-insensitive realisation of switched-capacitor leapfrog ladder filters with reduced number of operational amplifiers
Importance of rapid damping of relaxation oscillations for high-performance optical communication systems
  • Author(s): G.P. Agrawal  and  T.M. Shen
  • Source: Electronics Letters, Volume 22, Issue 20, p. 1087 –1088
  • DOI:  10.1049/el:19860745
  • Type: Article
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  • p. 1087 –1088 (2)
    The performance of a 1.55 μm lightwave transmission system employing directly modulated single-frequency semiconductor lasers depends on the dynamic characteristics such as the wavelength chirp and the damping of relaxation oscillations. Numerical simulations which include the effect of fibre dispersion and decision-time jitter on the detected power show that rapid damping of relaxation oscillations is critically important for high-bit-rate systems. We discuss how the system performance can be improved by optimising certain laser parameters.
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InGaAs/InAlAs heterojunction Schottky transistors grown by MBE
Erratum: Fast convergence method for Lloyd-Max quantiser design
Erratum: Spontaneous Brillouin scattering for single-mode optical-fibre characterisation

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