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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 20, Issue 4, 16 February 1984

Volumes & issues:

Volume 20, Issue 4

16 February 1984

Optical triggering of a trapped plasma
  • Author(s): H. Gottstein
  • Source: Electronics Letters, Volume 20, Issue 4, p. 149 –150
  • DOI:  10.1049/el:19840099
  • Type: Article
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  • p. 149 –150 (2)
    Dense electron-hole pairs trapped in a semiconductor p+-n-n+ structure form a trapped plasma that can conventionally be triggered by applying an overdriven electrical field to initiate impact ionisation. A new optical triggering mode is presented, which uses short light pulses at an electrical field just below the critical level. The optically generated carriers are separated by the applied electrical field and locally raise the electrical field which excites the impact ionisation. The letter describes the physical properties of the triggering process and the results of a one-dimensional computer simulation.
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Aggregation matrix for the reduced-order modified Cauer CFE model
Unity-gain frequency-independent precision phase-shifter
  • Author(s): R.G. Chambers
  • Source: Electronics Letters, Volume 20, Issue 4, p. 151 –152
  • DOI:  10.1049/el:19840101
  • Type: Article
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  • p. 151 –152 (2)
    The letter describes an operational amplifier circuit which gives a constant (±0.1°) phase shift and a constant (±0.1%) unity gain to a sinusoidal signal, over a frequency band of range ±2%. The circuit incorporates two standard phase-shifters with different characteristics, deployed so that their phase errors mutually cancel as the frequency deviates from its central value. The device has been used as a phase-shifter in a precise negative phase sequence current measurement circuit in a power system.
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‘Source-pull’ technique at microwave frequencies
High-capacity 1.3 μm unrepeatered optical fibre transmission system trials for submarine applications
94 GHz slotted waveguide array fabricated by photolithographic techniques
On solving Poisson's equation in two-dimensional semiconductor devices
InP/InGaAs buried-structure avalanche photodiodes
  • Author(s): K. Yasuda ; Y. Kishi ; T. Shirai ; T. Mikawa ; S. Yamazaki ; T. Kaneda
  • Source: Electronics Letters, Volume 20, Issue 4, p. 158 –159
  • DOI:  10.1049/el:19840106
  • Type: Article
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  • p. 158 –159 (2)
    Planar InP/InGaAs avalanche photodiodes with a new guardring structure have been designed and fabricated. The diodes had a buried n-InP layer and an n−-InP multiplication region under p-n junctions. A successful guardring effect was obtained. The diode exhibited a uniform multiplication over the active region, a maximum multiplication factor of 30, low dark currents of around 20 nA at 90% of breakdown voltage and a flat frequency response up to 1 GHz. Multiplication noise was measured up to a multiplication factor of 17.
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Practical barrier to hydrogen diffusion into optical fibres
  • Author(s): K.J. Beales ; D.M. Cooper ; W.J. Duncan ; J.D. Rush
  • Source: Electronics Letters, Volume 20, Issue 4, p. 159 –161
  • DOI:  10.1049/el:19840107
  • Type: Article
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  • p. 159 –161 (3)
    The diffusion of hydrogen (at 65 atm) into optical fibres coated with silicon oxynitride is found to be several orders of magnitude lower than that for uncoated fibres. Extrapolation of the data using a diffusion model predicts that such coatings should provide a practical and effective barrier against lower hydrogen pressures over system lifetimes. Thus all hydrogen-related optical ageing effects are significantly reduced.
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Equivalent-step-index-fibre determination from wavelength dependence of far field
  • Author(s): R. Srivastava ; J.A. Roversi ; A.C. Campos
  • Source: Electronics Letters, Volume 20, Issue 4, p. 161 –162
  • DOI:  10.1049/el:19840108
  • Type: Article
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  • p. 161 –162 (2)
    We compare two simple techniques for determination of equivalent-step-index parameters in single-mode fibres from measurement of the wavelength dependence of the far-field intensity profile. In one case the data is fitted directly by the step-index formula to yield the core radius and the v-value. In the other, wavelength dependence of the half-intensity angle is fitted to an empirical expression recently reported to give the core radius and the cutoff wavelength.
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Subnanosecond pulse propagation in a Goubau line immersed in a lossy dielectric medium
100 Mbit/s ASK heterodyne detection experiment using 1.3 μm DFB-laser diodes
Liquid-phase-epitaxial growth of Inp/InGaAsP/InGaAs buried-structure avalanche photodiodes
  • Author(s): Y. Kishi ; K. Yasuda ; S. Yamazaki ; K. Nakajima ; I. Umebu
  • Source: Electronics Letters, Volume 20, Issue 4, p. 165 –167
  • DOI:  10.1049/el:19840111
  • Type: Article
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  • p. 165 –167 (3)
    An InP/InGaAsP/InGaAs avalanche photodiode with an effective guard-ring structure has been successfully fabricated. The diode has a planar structure with an n-InP layer buried by n−-InP in the multiplication region The structure has been grown on a (111)A-oriented InP substrate by two-step growth of liquid-phase epitaxy. Prior to the second growth of n−-InP a meltback technique was used to reduce dark current.
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Measurement of chromatic dispersion of long spans of single-mode fibre: a factory and field test method
Novel application of generalised current conveyor
  • Author(s): R. Senani
  • Source: Electronics Letters, Volume 20, Issue 4, p. 169 –170
  • DOI:  10.1049/el:19840113
  • Type: Article
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  • p. 169 –170 (2)
    It is shown that the generalised current conveyor (characterised by the instantaneous terminal relations iy=h12ix, vx=h21vy and iz=h32ix) in conjunction with an activc-RC network derived from a given grounded immittance simulation network (i.e. 1-port with Y11=y(s)) can be used to realise the same type of immitance function in floating form (i.e. as a 2-port characterised by y11=−y12=−y21=y22=ky(s), k being a positive scale factor) with several advantages over earlier methods of floating immittance synthesis.
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Modified algorithm for two-dimensional convolutions by polynomial transforms
  • Author(s): H. Sun
  • Source: Electronics Letters, Volume 20, Issue 4, p. 171 –172
  • DOI:  10.1049/el:19840114
  • Type: Article
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  • p. 171 –172 (2)
    Recently two new methods for computing two-dimensional convolutions by using fast polynomial transforms have been published, by Pei and Wu (1981) and Martens (1982). Analysis shows, however, that it is impossible to obtain the expected higher efficiency with the new methods as compared to the FPT-FFT-CRT algorithm presented by Truong et al. (1981). A modified method is proposed in the letter, with which a gain in efficiency of 2–5% can be achieved.
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Sample-by-sample approach to recursive noncausal filtering
Influence of growth conditions on deep levels in molecular-beam-epitaxial GaAs
  • Author(s): C. Amano ; A. Shibukawa ; K. Ando ; M. Yamaguchi
  • Source: Electronics Letters, Volume 20, Issue 4, p. 174 –175
  • DOI:  10.1049/el:19840116
  • Type: Article
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  • p. 174 –175 (2)
    Molecular-bearn-epitaxially grown undoped GaAs layers are studied with regard to the relation between growth conditions and deep-level trap generation. Both carrier concentration and electron trap density have a minimum value in samples grown at close to the minimum As/Ga flux ratio under As-stabilised conditions. Growth under these conditions leads to suppression of defect generation and unintentional impurity incorporation.
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Electron beam annealing of zinc implanted GaAs to control profile broadening
Three-channel buried-crescent InGaAsP laser with 1.51 μm wavelength on semi-insulating InP
Chlorine concentration profiles in silica fibres
Analytical formulas for coplanar lines in hybrid and monolithic MICs
Two-layer circularly polarised microstrip antenna
Raman spectra of hydrogen-treated optical fibres
Nonreciprocal phase shift in finline with layered substrate containing magnetised ferrite
Stimulated Raman crosstalk in optical transmission: effects of group velocity dispersion
Use of MOS transistor as a tunable distributed RC filter element
Composite dielectric waveguide

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