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image of Volume 24, Issue 23
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 23, 10 November 1988

Volumes & issues:

Volume 24, Issue 23

10 November 1988

New data regeneration scheme for multi-Gbit/s fibre-optic links
100Gbit/s optical signal generation by time-division multiplication of modulated and compressed pulses from gain-switched distributed feedback (DFB) laser diode
1.5μm λ/4 shifted multiple quantum well distributed feedback laser diodes
New scattering matrix parameter formulas for transmission mode dielectric resonator filter networks
Quasi-optical measurement of carcinotron phase noise at 350 GHz
  • Author(s): A. van Ardenne  and  W. Melis
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1411 –1413
  • DOI:  10.1049/el:19880964
  • Type: Article
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  • p. 1411 –1413 (3)
    Phase noise of a single carcinotron operating at 350 GHz, at offset frequencies in the range 105–107Hz, from the carrier has been measured. A quasi-optical analogue of the delay line frequency discriminator method was used, demonstrating a simple method capable of measuring phase noise in the (sub)mm region. The results obtained are of practical use in the design of phase locked systems, in the wavelength region used.
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Time-multiplexed analogue circuit for implementing artificial neural networks
Method for analysing trapezoidal optical waveguides by an equivalent rectangular rib waveguide
140 Mbit/s receiver performance at 2.4μm using InAsSbP detector
Optical fibre up-taper back-reflector for laser transmitter evaluation
  • Author(s): A.F. Benner ; D.A. Fishman ; H.M. Presby
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1417 –1418
  • DOI:  10.1049/el:19880968
  • Type: Article
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  • p. 1417 –1418 (2)
    Evaluation of reflection effects on semiconductor laser transmitters is complicated by multipath interference, which causes degradations in bit-error-rate and is independent of laser isolation. We have constructed a variable back-reflector utilising optical fibre up-tapers, which eliminates multipath interference effects by reducing spurious reflection levels to below −50dB. Reflection levels of −50dB to −16.5dB into the laser cavity are possible. Results of measurements of reflection effects on several multilongitudinal mode 1.3μm lasers operating at 1.7Gbit/s are shown.
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Role of guided acoustic wave properties in single-mode optical fibre design
Raman characterisation of stress in recrystallised silicon-on-insulator
Demonstration of 3 pT/√(Hz) at 10 Hz in a fibre-optic magnetometer
Error probabilities for wavelength-shift-keyed optical communications
Low-threshold, high-power, single-longitudinal-mode operation in 1.5μm multiple-quantum-well, distributed-feedback laser diodes
All-optical timing extraction using a 1.5μm self pulsating multielectrode DFB LD
2×2 optical fibre polarisation switch and polarisation controller
Constant-temperature integrated vacuum sensor
  • Author(s): J.-B. Huang  and  Q.-Y. Tong
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1429 –1430
  • DOI:  10.1049/el:19880976
  • Type: Article
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  • p. 1429 –1430 (2)
    An integrated vacuum sensor based on heat transfer at a constant chip temperature (CCT) is introduced. It consists of a temperature-sensing stage, a CMOS op-amp and a heating branch circuit. All three parts are integrated on one chip and connected to form a negative feedback loop for CCT operation. The heating power of the sensor chip was used to indicate the vacuum which affects the heat transfer between the chip and the vacuum ambient.
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Optical samplers for gigabit cable TV receivers
Continuously tunable 1.5μm multiple-quantum-well GaInAs/GaInAsP distributed-Bragg-reflector lasers
The SSFIP: a global concept for high-performance broadband planar antennas
Simple bounds on modal propagation constant for arbitrarily shaped optical fibres
  • Author(s): I.M. Skinner  and  C. Pask
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1435 –1436
  • DOI:  10.1049/el:19880980
  • Type: Article
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  • p. 1435 –1436 (2)
    We show that, when a fibre core cross-section is distorted from circular, the fundamental mode propagation constant β always decreases. To complement the upper bound on β thus obtained, we give a second approximation to β giving a simple lower bound and which only requires computation of a geometric shape factor and results for circular cross-sections. The results hold for arbitrary shape and grading.
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Simple fibre-optic multiplexing system using pseudorandom sequence
Uniqueness of solutions of piecewise linear resistive networks with two terminal resistors
  • Author(s): V.C. Prasad  and  V.P. Prakash
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1438 –1439
  • DOI:  10.1049/el:19880982
  • Type: Article
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  • p. 1438 –1439 (2)
    Consider a network comprising two terminal linear, piecewise linear resistors and independent sources. Contrary to widely held belief, it is shown that the determinant sign condition (i.e. the Jacobian determinant is nonzero and has the same sign in all the regions) is both necessary as well as sufficient to guarantee uniqueness of solutions of these networks. For this purpose we do not require the existence of specific hybrid matrix.
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Active mode-locking of an external cavity GaInAsP laser incorporating a fibre-grating reflector
  • Author(s): D. Burns ; D.W. Crust ; J.T.K. Chang ; W. Sibbett
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1439 –1441
  • DOI:  10.1049/el:19880983
  • Type: Article
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  • p. 1439 –1441 (3)
    Active mode-locking of a GaInAsP semiconductor diode amplifier, coupled to an external cavity incorporating an optical fibre grating as a bandwidth limiting and wavelength selective mirror, is reported. The grating defined the central emission wavelength to the 1.53μm region where modelocked pulses having durations ofless than 10 ps were generated at a repetition rate of 648 MHz.
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High-speed electron beam testing using an electron-optical phase shift element
  • Author(s): J.T.L. Thong ; B.C. Breton ; W.C. Nixon
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1441 –1442
  • DOI:  10.1049/el:19880984
  • Type: Article
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  • p. 1441 –1442 (2)
    An electron-optical element has been developed which delays electron pulses with continuous phase shift resolution. The inherently jitter-free method relies on the change of beam potential over a length of the optical path to modify the electron pulse transit time. Direct pulse measurements using 5 ps pulses demonstrate subpicosecond resolved delays while waveforms have been measured on coplanar lines.
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Comparison of T0-values of bulk and quantum-well semiconductor lasers
Integrated InP/GaInAs heterojunction bipolar photoreceiver
High-power microwave generation from virtual cathode in foilless diode (vircator)
  • Author(s): N.A. Nikolov ; K.G. Kostov ; I.P. Spasovsky ; V.A. Spasov
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1445 –1446
  • DOI:  10.1049/el:19880987
  • Type: Article
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  • p. 1445 –1446 (2)
    In this letter we investigate experimentally the microwave radiation generation in a foilless diode. The source of the radiation is a virtual cathode which is formed by the injection of excess current into the drift region. The behaviour of microwave power from an external guiding magnetic field is investigated for three cathode diameters. Symmetrical and nonsymmetrical TM modes are observed, and the wavelength f radiation is measured. The peak microwave power produced was 10±5 MW, which corresponds to 1% efficiency.
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Electrical activity of Yb in InP
Further results on class of sequences with good autocorrelation and high linear complexity
  • Author(s): S. Prasad ; P.V.A. Narasimhan ; L.C. Quynh
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1447 –1449
  • DOI:  10.1049/el:19880989
  • Type: Article
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  • p. 1447 –1449 (3)
    A simple modification of the m-like sequences introduced recently is shown to lead to an interesting class of sequences. The autocorrelation function of these ‘modified m-like sequences’ is seen to have the sidelobe values of − 1 and 3, as against the uniform sidelobe level of − 1 for the m-like sequences previously given. For the price of this marginal deterioration in the ACF properties, the modified sequences are shown to provide a considerable increase in the linear complexity, particularly for long sequences.
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Large bandwidth circular slot at resonance with directional radiation
Depletion and saturation effect of stimulated Raman scattering
  • Author(s): Chen Yijiang  and  A.W. Snyder
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1450 –1452
  • DOI:  10.1049/el:19880991
  • Type: Article
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  • p. 1450 –1452 (3)
    The depletion and saturation effect of stimulated Raman scattering in optical fibres has been investigated. Nonlinear energy coupled equations are solved analytically. Our study reveals that the Raman gain saturation effect caused by the generation of the second Stokes has to be taken into account in light amplification by stimulated Raman scattering although it can be ignored in spontaneous stimulated Raman scattering. We also show that it is advantageous to feed the fibre with small low Stokes signals in amplifying high-order Stokes signals, for easing the requirement of high pump power and long fibre length.
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New-type phase-locked loop using travelling-wave laser-diode optical amplifier for very high-speed optical transmission
Liquid crystal all-fibre optical polariser
1 Gbit/s zero-IF DPSK coherent optical system using a single photodetector
Balanced dual photodiodes integrated with a 3 dB directional coupler for coherent lightwave receivers
  • Author(s): S. Chandrasekhar ; J.C. Campbell ; F.G. Storz ; A.G. Dentai ; C.H. Joyner ; G.J. Qua
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1457 –1458
  • DOI:  10.1049/el:19880995
  • Type: Article
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  • p. 1457 –1458 (2)
    A photonic integrated circuit consisting of a 3 dB directional coupler and two GaInAs pin photodiodes connected in series at the output of the coupler has been fabricated. The photodiodes have typical dark currents of approximately 3 nA at a reverse bias of 8 V, with more than 1 MΩ isolation. Symmetrical operating characteristics with respect to the launching direction have been achieved.
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Intense and sharply structured 1.54μm room-temperature luminescence of Er-doped GaAs/AlGaAs structures grown by MBE
  • Author(s): M.N. Charasse ; P. Galtier ; A.M. Huber ; C. Grattepain ; J. Chazelas ; J.P. Hirtz
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1458 –1460
  • DOI:  10.1049/el:19880996
  • Type: Article
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  • p. 1458 –1460 (3)
    Er doping of GaAs, AlGaAs and quantum wells (QW) has been achieved by MBE. A new type of Er3+ centre is observed in AlGaAs and QW structures, which is characterised by a main peak at 1.565μ at 4.5 K. At 300 K, the main peak is always at 1.54μ. In the case of QW structures, its linewidth goes down to only 1 meV and it is surrounded by up to 16 less intense peaks.
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State of polarisation and phase noise independent coherent optical transmission system based on Stokes parameter detection
1 Gbit/s RZ zero-bias modulation of extremely low-threshold GaInAsP/InP DFB PPIBH laser
Tunable continuous-wave, room-temperature Er3+-doped ZrF4-based glass laser between 2.69 and 2.78μm
Modelling of microstrip antenna with dielectric protective layer for lossy medium
  • Author(s): J. Pribetich ; R. Ledee ; P. Kennis ; P. Pribetich ; M. Chive
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1464 –1465
  • DOI:  10.1049/el:19881000
  • Type: Article
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  • p. 1464 –1465 (2)
    Microstrip antennas are used for biomedical applications; however, their modelling is not easy. We present an approach to simulating a microstrip antenna with a dielectric protective layer radiating into a lossy medium. Using a classical spectral domain approach (SDA) model, calculations of the resonant frequency have been performed, and compared with experimental measurements for simple structures of microstrip antenna with different geometric parameters.
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One-sided switching networks composed of partial access switching blocks
Approximate theory for radiation from mesh reflectors
  • Author(s): G.T. Poulton ; H. Zhou ; P.J.B. Clarricoats
  • Source: Electronics Letters, Volume 24, Issue 23, p. 1467 –1468
  • DOI:  10.1049/el:19881002
  • Type: Article
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  • p. 1467 –1468 (2)
    Reconfigurable shaped reflector antennas have potential applications in satellite communications and satellite broadcasting. When a metallic mesh is employed pillowing occurs between the points at which the reflector is constrained. The letter describes an approximate theory to explain the behaviour, and results are obtained which are in good agreement with exact analysis. The new theory allows key features to be identified which show that the principal effect is to produce gain loss, and furthermore that for an isotropic mesh tension does not influence this loss.
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Full two-dimensional modelling of broadband SAW filters
Optical chemical sensing employing surface plasmon resonance

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