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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 13, 23 June 1988

Volumes & issues:

Volume 24, Issue 13

23 June 1988

Laser diode frequency stabilisation to Doppler-free rubidium spectra
Single-mode fibres with extremely high-Δ and small-dimension pure GeO2 core for efficient nonlinear optical applications
  • Author(s): T. Hosaka ; S. Sudo ; H. Itoh ; K. Okamoto
  • Source: Electronics Letters, Volume 24, Issue 13, p. 770 –771
  • DOI:  10.1049/el:19880522
  • Type: Article
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  • p. 770 –771 (2)
    Single-mode fibres with 8.2% Δ and a 1.4µm diameter-GeO2 core have been prepared for efficient stimulated Raman effect. When pumping a 2.7 m-long fibre by a Q-switched and mode-locked Nd:YAG laser (λ=1.064µm), the first Stokes light (λ=1.114µm) and second Stokes light (λm=1.169µm) have been observed at the input peak power levels of 24 W and 40 W, respectively. These results indicate that the above critical power levels are approximately 10−2 ∼ 10−3 smaller than those for the high-silica single-mode fibre.
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Reservation-based contention resolution mechanism for batcher-banyan packet switches
Vector quantisation of wideband transform coefficient time trajectories in speech coding
  • Author(s): T. Fjällbrant  and  F. Mekuria
  • Source: Electronics Letters, Volume 24, Issue 13, p. 773 –774
  • DOI:  10.1049/el:19880524
  • Type: Article
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  • p. 773 –774 (2)
    A number of methods to perform efficient dynamic bit allocation to perceptually important parameters in the frequency domain result from the combination of vector quantisation techniques and wideband transform coding. Time trajectories of transform coefficients and of magnitude and phasederivative coefficients are used as vectors for vector quantisation. Speech coders implementable in single DSPs with external memory, having short delay and high robustness to bit stream distortions have been developed.
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Realisation of very high transconductance GaAs MESFETs
  • Author(s): P. Godts ; J. Vanbremeersch ; E. Constant ; J. Zimmermann
  • Source: Electronics Letters, Volume 24, Issue 13, p. 775 –776
  • DOI:  10.1049/el:19880525
  • Type: Article
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  • p. 775 –776 (2)
    By using a model which considers velocity overshoot, it is shown that the performance of GaAs MESFETs in enhancement mode depends strongly on the geometrical and electrical characteristics of the access region between source and gate. The square resistance of the unrecessed epilayer, and the distance between the source-end of the recessed region and the gate, have to be as low as possible. 300 nm gate length MESFETs with very low values for these parameters were realised with an n-GaAs active layer (6 × 1017cm−3). These devices exhibit very high microwave transconductances (800mS/mm) with good cutoff frequencies (up to 55 GHz). This result suggests that very high transconductance MESFETs can be fabricated from not-too-heavily doped active layers provided that the characteristics of the source-gate access region is properly optimised.
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Voltage-controlled oscillator using dielectric resonator
Self-excited vibrations of optical microresonators
Optical receiver employing 850 nm feedback
Operational simulation of highpass RLC filters
Systolic arrays for matrix I/O format conversion
  • Author(s): N. Petkov
  • Source: Electronics Letters, Volume 24, Issue 13, p. 781 –782
  • DOI:  10.1049/el:19880530
  • Type: Article
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  • p. 781 –782 (2)
    New 1-slow and 2-slow systolic arrays for row-to-diagonal and diagonal-to-row input/output format conversion of matrices are given. For n×n matrices, the arrays consist of n2 cells. A 1-slow systolic array performs the conversion in 2n−1 periods. The arrays can be used also for column-to-diagonal, diagonal-to-column, row-to-column and column-to-row input/output format conversions. The 1-slow array performs these operations in 2n−1, 2n−1, and 3n−1 periods, respectively.
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Performance analysis of CA-CFAR in the presence of compound Gaussian clutter
Fibre-optic coriolis mass flowmeter for liquids
Optical pulse compression in 1.5µm wavelength region using large-positive-dispersion fibre and grating pair
Reduced spontaneous emission factor in quantum-well lasers
Normally off GaAs DC-8 GHz amplifier
Study of microdefects in near-surface and interior of III-V compound wafers by dark-field transmission microscopy
Integrated communication and sensing system using one single-mode optical fibre
Quasi-optical resonator for millimetre and sub millimetre wave solid-state sources
Electrostatic beam pumping method for intense relativistic cyclotron maser
  • Author(s): N.A. Nikolov ; I.P. Spasovsky ; J.N. Velichkov ; A.G. Shkvarunets ; I.P. Trifonov ; V.A. Spasov
  • Source: Electronics Letters, Volume 24, Issue 13, p. 793 –794
  • DOI:  10.1049/el:19880539
  • Type: Article
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  • p. 793 –794 (2)
    The letter presents an electrostatic method of beam pumping for a relativistic cyclotron maser of high power output in the centimetre range by the creation of an electrostatic inhomogeneity in a foilless diode and the drift region in a spatially-homogeneous magnetic field. The experimental optimisation of this method has given the following results: single-mode microwave radiation with power 60±10 MW and electronic efficiency 10% at wavelength λ=2.4±0.1 cm.
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1.55 µm wavelength region high-stability optical fibre loss variation measurement using fibre coupler
Three-view co-ordinate computation
New experimental results of millimetre-wave whispering gallery mode dielectric resonators excited by microstrip lines
Reactive ion etching of III-V compounds using C2H6/H2
All-optical flip-flop operations in a coupled element bistable device
Dispersion-flattened single-mode fibres with minimised dopant expenditure
Illuminated ballistic camel diode: a new optoelectronic negative resistance device
Frequency stabilisation of a 1.3 μm DFB laser to an argon line using optogalvanic effect
Optical fibre polishing with a motor-driven polishing wheel
New boundary integral equation for CAD of waveguide circuit
  • Author(s): K. Tanaka  and  M. Kojima
  • Source: Electronics Letters, Volume 24, Issue 13, p. 807 –808
  • DOI:  10.1049/el:19880549
  • Type: Article
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  • p. 807 –808 (2)
    A new type of boundary integral equation is proposed which is suitable for the CAD of waveguidecircuits. The new integral equation can be obtained by considering specific conditions at points far away from the discontinuity. The new boundary integral equation is derived for the scattering problem of a corner bend. Numerical solution by the conventional boundary element method establishes the validity of the new boundary integral equation.
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Optical detection up to 2.5 Gbit/s with a standard high-speed self-aligned silicon bipolar transistor
Numerical implementation of the Gabor representation
Prediction of circular array phase mode characteristics
Minimum switches for varying connections on eight telephone lines
Coupling among waveguides of small spacing
Double-interdigitated (TIL) bipolar transistor with heavily doped base wells
  • Author(s): A.P. Silard  and  G. Nani
  • Source: Electronics Letters, Volume 24, Issue 13, p. 815 –817
  • DOI:  10.1049/el:19880555
  • Type: Article
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  • p. 815 –817 (3)
    The letter reports the development of two interdigitation level (TIL) bipolar transistors with heavily-doped base wells (BW), having the following advantages in comparison with identical conventional devices: (a) an ∼18% and ∼23% increase of voltages VCEO(SUS) and VCBO, respectively; (b) a reduction of the turn-on delay (td)and rise (tr) times by a factor of ∼20; (c) a two-fold decrease of the fall time tf.
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Monte Carlo simulations of repeated velocity overshoot structures
  • Author(s): P.H. Beton ; A.P. Long ; M.J. Kelly ; P.M. Matthews
  • Source: Electronics Letters, Volume 24, Issue 13, p. 817 –818
  • DOI:  10.1049/el:19880556
  • Type: Article
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  • p. 817 –818 (2)
    We have performed self-consistent Monte Carlo simulations on repeated velocity overshoot structures. From our calculations, we may assess the potential of such structures to enhance the average drift velocity of electrons. We find that there is no enhancement for uniformly doped structures. For spike-doped structures there is a small enhancement, but this is gained at the expense of a drop in current density. In both structures the velocity enhancement is limited by intervalley scattering.
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Direct observation of optical wave breaking of picosecond pulses in nonlinear single-mode optical fibres
Rigorous analysis of triple-ridge waveguides
  • Author(s): J.W. Tao  and  H. Baudrand
  • Source: Electronics Letters, Volume 24, Issue 13, p. 820 –821
  • DOI:  10.1049/el:19880558
  • Type: Article
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  • p. 820 –821 (2)
    A complete eigenvalue solution is presented for a triple-ridge waveguide which yields the cut-off frequencies of dominant and higher-order modes as a function of the geometrical parameters of the guide. The electromagnetic field distribution is determined in the waveguide cross-section allowing the calculation of the dominant mode impedance. The Ritz-Galerkin method is used for the numerical calculations, and edge effects are taken into account in the basis functions toaccelerate the convergence. This method can be applied to multiridge waveguides with an arbitrary disposition of ridges.
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Measurement of line width enhancement factor of semiconductor lasers by modified direct frequency-modulation method
  • Author(s): K. Kikuchi  and  H. Iwasawa
  • Source: Electronics Letters, Volume 24, Issue 13, p. 821 –822
  • DOI:  10.1049/el:19880559
  • Type: Article
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  • p. 821 –822 (2)
    The frequency modulation characteristics of 1.3 μm DFB lasers below the relaxation resonancereveal two different types of response: the in-phase response between the frequency modulation (FM) and the amplitude modulation (AM), and the out-of-phase response between them. In both cases, the ratio of the FM index to the AM index is strongly dependent on the modulation frequency; however, when the modulation frequency is increased beyond the relaxation resonance, this value approaches the linewidth enhancement factor. On the basis of this result, the linewidth enhancement factors of 1.3 μm DFB lasers with different amounts of wavelength detuning are determined.
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Wavelength uniformity of 1.3 μm GaInAsP/InP distributed Bragg reflector lasers with hybrid beam/vapour epitaxial growth
  • Author(s): T.L. Koch ; P.J. Corvini ; U. Koren ; W.T. Tsang
  • Source: Electronics Letters, Volume 24, Issue 13, p. 822 –824
  • DOI:  10.1049/el:19880560
  • Type: Article
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  • p. 822 –824 (3)
    We report 1.3 μm distributed Bragg reflector (DBR) lasers with a hybrid growth employing base wafers grown by chemical beam epitaxy (CBE), and Fe-doped InP lateral current blocking grown by metal-organic chemical vapour deposition (MOCVD). These lasers display exceptional wavelength uniformity (σ ∼ 27 Å) across the wafer, and suggest that DBR lasers and vapour/beam growth techniques may be suitable for advanced WDM applications.
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GaInAsP/InP single-quantum-well (SQW) laser with wire-like active region towards quantum wire laser
  • Author(s): M. Cao ; P. Daste ; Y. Miyamoto ; Y. Miyake ; S. Nogiwa ; S. Arai ; K. Furuya ; Y. Suematsu
  • Source: Electronics Letters, Volume 24, Issue 13, p. 824 –825
  • DOI:  10.1049/el:19880561
  • Type: Article
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  • p. 824 –825 (2)
    Lasing operation of a GaInAsP/InP single-quantum-well laser with very narrow (0.12 μm) wire-likeactive region was obtained for the first time under CW condition at 77 K. It was fabricated by a two-step organometallic vapour phase epitaxy (OMVPE) and wet chemical etching process. The threshold current density of the laser was 810 A/cm2. This lasing operation with such a narrow active region indicates that the technique employed here would be suitable for realising a higher-dimensional quantum-well laser, such as quantum wire and box lasers.
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Erratum: Performance of mean-level detector in presence of multiple-tone interference plus noise

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