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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 6, 17 March 1988

Volumes & issues:

Volume 24, Issue 6

17 March 1988

Improved binary frame synchronisation scheme for packet transmission
Enhanced damping of laser diode relaxation oscillations from revised rate equations
  • Author(s): J. Arnaud
  • Source: Electronics Letters, Volume 24, Issue 6, p. 302 –303
  • DOI:  10.1049/el:19880203
  • Type: Article
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  • p. 302 –303 (2)
    The standard rate equations are incomplete when the optical cavity conductance depends on the optical frequency at the operating point. Corrected rate equations are given in the paper, that involve an action of frequency back on the amplitude. The number of relaxation oscillations is found to be much smaller than that calculated from standard rate equations when the optical wave is weakly index guided, as in CSP lasers. The revision of the rate equations proposed in the paper may affect most laser characteristics.
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Recovery time for a silicon waveguide all-optical switch
400 Mbit/s optical heterodyne DPSK system experiment with inline 1.5μm amplifiers
Transverse folding algorithm for PLAs
  • Author(s): C. Bhat  and  N.N. Biswas
  • Source: Electronics Letters, Volume 24, Issue 6, p. 306 –308
  • DOI:  10.1049/el:19880206
  • Type: Article
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  • p. 306 –308 (3)
    The letter reports a new concept for transverse folding of programmable logic arrays (PLAs). With the new definitions for the compatibility and foldability of rows (columns) of a column-folded (row-folded) PLA, the transverse compatibility-cum-foldability matrix (TCFM) is plotted. From the TCFM, a transverse folding matrix (TFM) is found, from which the row (column) folding pairs and the resulting ordering of rows and columns are obtained.
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Optical second harmonic generation from Langmuir-Blodgett multilayers containing preformed polymers
PVDF transducers generating Scholte waves
Tunable sandwich transducer
  • Author(s): S.K. Jain  and  B.V. Smith
  • Source: Electronics Letters, Volume 24, Issue 6, p. 311 –312
  • DOI:  10.1049/el:19880209
  • Type: Article
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  • p. 311 –312 (2)
    A tunable sandwich transducer is reported which has its fundamental resonant frequency controllable by varying a passive reactive load. The structure consists of four PZT-4 rings sandwiched between an aluminium head-mass and a brass tail-mass. The electromechanical coupling coefficient and the radiation efficiency into water of the transducer are given over the frequency range 25 to 75 kHz. A theoretical analysis based on an electromechanical equivalent circuit shows good agreement with the experimental results.
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Fused taper/filter hybrid single-mode wavelength division multi/demultiplexer
High-speed GaInAs/InP multiquantum well avalanche photodiodes grown by atmospheric-pressure MOCVD
  • Author(s): A.J. Moseley ; J. Urquhart ; J.R. Riffat
  • Source: Electronics Letters, Volume 24, Issue 6, p. 313 –315
  • DOI:  10.1049/el:19880211
  • Type: Article
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  • p. 313 –315 (3)
    We report the performance of the first high speed GaInAs/InP multi-quantum well avalanche photodiodes grown by atmospheric pressure MOCVD. The multi-quantum well avalanche region of the device consists of 50 periods of 150 Å wells and barriers forming the intrinsic region of a pin structure. Avalanche multiplication up to a factor of 25 has been measured at DC together with high-speed response giving a maximum measured RF gain of 16 and a gain-bandwidth product in excess of 25 GHz.
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Order N log2N WHT/DHT algorithm
Computer simulation of a mobile packet radio system
Flat printed reflector antenna for mm-wave applications
Heterojunction InP/GaInAs phototransistors/bipolar transistors grown by MOVPE
  • Author(s): S. Chandrasekhar ; J.C. Campbell ; A.G. Dentai ; C.H. Joyner ; G.J. Qua ; O. Sugiura
  • Source: Electronics Letters, Volume 24, Issue 6, p. 319 –320
  • DOI:  10.1049/el:19880215
  • Type: Article
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  • p. 319 –320 (2)
    Heterojunction InP/GaInAs phototransistors with base terminals have been fabricated by atmospheric pressure metal organic vapour phase epitaxy. When operated as bipolar transistors, the devices exhibit high current gain (>1600) and good junction ideality factors (1.06 for the base/emitter and 1.25 for the base/collector junction). When operated as phototransistors, the devices have large optical gain (>800) at an incident power of 1 μW, at a wavelength of 1.3μm.
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Laser emission of Er+3 in ZrF4-based fluoride glass
Resonant tunnelling in Ga0.47In0.53As/InP double-barrier structures grown by AP-MOCVD
Simplified laser to fibre coupling via optical fibre up-tapers
Simplified numerical approach to Mueller's design of optimum linear phase pulse shaping filter
High-power AlGaInP three-ridge type laser diode array
Frequency-diversity improvement in n/1 high-capacity digital microwave radio
Computation of large-signal S-parameters by harmonic-balance techniques
Measurement of excess sensitivity penalty of a four-diode polarisation diversity coherent receiver
  • Author(s): L.D. Tzeng ; T.W. Cline ; A.A.M. Saleh
  • Source: Electronics Letters, Volume 24, Issue 6, p. 330 –332
  • DOI:  10.1049/el:19880223
  • Type: Article
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  • p. 330 –332 (3)
    A novel optical polarisation-diversity coherent receiver is described and demonstrated. The receiver optical hybrid consists of three polarising beam splitters and four pin diodes, interconnected with polarisation maintaining fibres. Measurements over arbitrary input polarisations show a receiver sensitivity of −63±0.5dBm for BER of 10−9 in a 40Mbit/s DPSK self-heterodyne system. This receiver sensitivity is within 1±0.5 dB of the sensitivity of a single-channel receiver with matched signal and local oscillator polarisation.
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Local field in a bent step index fibre
Linear unequal error-protection array codes
Effective recursive algorithm for computing multiplicative inverses in GF(2m)
Monolithically integrated laser/photodetector
  • Author(s): N.K. Dutta ; T. Cella ; J.L. Zilko ; A.B. Piccirilli ; R.L. Brown
  • Source: Electronics Letters, Volume 24, Issue 6, p. 335 –336
  • DOI:  10.1049/el:19880227
  • Type: Article
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  • p. 335 –336 (2)
    The fabrication and performance characteristics of a laser structure with monolithically integrated monitoring photodiode are described. The structure utilises semi-insulating Fe doped InP layers for confinement of the current to the active region of the laser and for the separation of the laser and the photodetector sections. The lasers have threshold currents in the range 30–40 mA and emit in a single frequency by virtue of frequency selective feedback, provided by a grating etched on the substrate. The photodetector provides ⋍300/μA of photocurrent per mW of laser power which is comparable to the value for a large area Ge photodiode generally used to monitor laser power. The new structure also minimises the unwanted reflection effects on laser performance caused by light reflected from the photodiode interface.
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Some experiments on speech vector quantisation at variable low bit rate
Distortion of the frequency modulation spectra of semiconductor lasers by weak optical feedback
4×4 all-fibre optical switching matrix
  • Author(s): A. El Fatatry ; S.P. Shipley ; R. Tyson
  • Source: Electronics Letters, Volume 24, Issue 6, p. 339 –340
  • DOI:  10.1049/el:19880230
  • Type: Article
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  • p. 339 –340 (2)
    This letter describes the fabrication and performance of a 4×4 nonblocking optical switching matrix for use with single-mode optical fibre systems. The configuration adopted uses individual 2×2 all-fibre switching units interconnected by fusion splices to form a 4×4 nonblocking matrix with a mean path insertion loss of 2.3 dB and a channel isolation better than −15 dB when operating at a wavelength of 1300nm.
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Demonstration of the optical Kerr effect in an all-fibre Mach-Zehnder interferometer at laser diode powers
Dc magnetron sputtering of Y-Ba-Cu-O on Si(100)
Low threshold current surface emitting AlGaAs/GaAs laser with 45° metallised reflector
  • Author(s): C.L. Shieh ; J. Mantz ; K. Alavi ; R.W.H. Engelmann
  • Source: Electronics Letters, Volume 24, Issue 6, p. 343 –344
  • DOI:  10.1049/el:19880233
  • Type: Article
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  • p. 343 –344 (2)
    A surface emitting AlGaAs/GaAs DH laser having one etched facet integrated with a 45° metallised reflector is demonstrated with a threshold current as low as 70 mA for a 6 μm (gain-guided) shallow mesa stripe geometry. The etched facet/45° mirror combination was fabricated by tilted ion beam milling through the p-metallisation of the processed wafer. A surface emitter with power as high as 70 mW is achieved with a 50μm stripe.
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Experimental demonstration of a passive optical subscriber loop architecture
  • Author(s): S.S. Wagner ; H. Kobrinski ; T.J. Robe ; H.L. Lemberg ; L.S. Smoot
  • Source: Electronics Letters, Volume 24, Issue 6, p. 344 –346
  • DOI:  10.1049/el:19880234
  • Type: Article
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  • p. 344 –346 (3)
    We report the experimental demonstration of a new passive optical subscriber loop architecture employing 20 channel WDM with 2 nm channel spacings. The experiment includes the demonstration of LED transmission in a dense, multiwavelength single-mode fibre network. The experiment also features simultaneous, bidirectional transmission with both LEDs (384 kb/s) and DFB lasers (up to 1.2 Gb/s).
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Effect of paramagnetic impurities on frequency of sapphire-loaded superconducting cavity resonators
Feedback induced microwave signal dropout in 0.83μm fibre-optic links
Performance studies of some microstrip structures using superconducting materials
  • Author(s): R.D. Standley  and  N.K. Cheung
  • Source: Electronics Letters, Volume 24, Issue 6, p. 349 –350
  • DOI:  10.1049/el:19880237
  • Type: Article
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  • p. 349 –350 (2)
    High-temperature superconducting materials can be used to fabricate microwave circuits with very low insertion loss and high Q values. Using computer simulation, we have shown that the loaded Q for certain microstrip configurations, which can be readily fabricated with simple lithographic techniques, can be made as high as the more difficult to produce dielectric resonator filters or surface acoustic wave (SAW) filters.
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Limitation of transmission distance and capacity due to polarisation dispersion in a lightwave system
  • Author(s): M. Tsubokawa  and  Y. Sasaki
  • Source: Electronics Letters, Volume 24, Issue 6, p. 350 –352
  • DOI:  10.1049/el:19880238
  • Type: Article
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  • p. 350 –352 (3)
    The length dependence of group delay differences between orthogonally polarised modes has been investigated experimentally for real single-mode fibres ranging from 0.1 km to 100 km. The mean group delay difference is a constant value of 0.67 ps, over a length of more than 1 km. The mode coupling coefficient of random mode mixing which causes pulse broadening has been estimated to be 6.3 × 10−3m−1. A light pulse will broaden by 17 ps after traversing a 100 km-long fibre. This may restrict single-mode fibre systems to a bit rate of 10 GHz for lengths over 150 km.
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Stability requirements for multiple laser diode extended range interferometry
Novel iron phosphate optical waveguides fabricated by a low temperature process
Field behaviour near a conducting edge embedded in an inhomogeneous anisotropic medium
  • Author(s): C.-H. Chan ; Z. Pantic-Tanner ; R. Mittra
  • Source: Electronics Letters, Volume 24, Issue 6, p. 355 –356
  • DOI:  10.1049/el:19880241
  • Type: Article
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  • p. 355 –356 (2)
    In this letter we consider the field behaviour in the neighbourhood of a conducting edge embedded in an inhomogeneous anistroptic medium which is described by arbitrary permittivity and permeability tensors. We derive an eigenequation, whose minimum root governs the behaviour of each of the field components in the vicinity of the edge. Numerical examples are given for some typical geometries encountered in waveguiding structures.
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Effects of dielectric superstrate on patch antennas
Polarisation-insensitive coherent lightwave system using wide-deviation FSK and data-induced polarisation switching
  • Author(s): L.J. Cimini ; I.M.I. Habbab ; S. Yang ; A.J. Rustako ; K.Y. Liou ; C.A. Burrus
  • Source: Electronics Letters, Volume 24, Issue 6, p. 358 –360
  • DOI:  10.1049/el:19880243
  • Type: Article
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  • p. 358 –360 (3)
    We present a technique wherein polarisation-insensitive heterodyne detection is achieved through data-induced polarisation switching. The polarisation switching is brought about by inserting a passive, birefringent optical device in the path of the transmitted FSK signal. The experimental results show that this technique suffers a power penalty of 3–4 dB when compared with a conventional FSK system with perfectly matched polarisations. This compares well with the expected penalty of 3 dB. This approach uses a single optical receiver and no additional receiver electronics, which could be a significant advantage for local area networks.
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Optical signal amplification at 1.3 μm by two-wave mixing in InP:Fe
Two-stage nonblocking bidirectional switch networks
Effects of feed wire on radiation characteristics of a dual spiral antenna
0.1 μm gate length MODFETs with unity current gain cutoff frequency above 110 GHz
  • Author(s): A.N. Lepore ; H.M. Levy ; R.C. Tiberio ; P.J. Tasker ; H. Lee ; E.D. Wolf ; L.F. Eastman ; E. Kohn
  • Source: Electronics Letters, Volume 24, Issue 6, p. 364 –366
  • DOI:  10.1049/el:19880247
  • Type: Article
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  • p. 364 –366 (3)
    AlGaAs/GaAs modulation-doped field-effect transistors (MODFETs) have been fabricated with ‘T’ cross-section 0.1 μm gates using electron-beam lithography. A unity current gain cutoff frequency fT of 113 GHz has been measured for a spike-doped MODFET with a GaAs buffer. This is the highest measured fT reported to date for FETs of any kind.
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Erratum: Definition of artificially soft and hard surfaces for electromagnetic waves

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