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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 11, 26 May 1988

Volumes & issues:

Volume 24, Issue 11

26 May 1988

Bidirectional multichannel 1.44 Gbit/s lightwave distribution system using subcarrier multiplexing
  • Author(s): T.E. Darcie ; P.P. Iannone ; J.R. Talman ; C.A. Burrus ; T.A. Baker
  • Source: Electronics Letters, Volume 24, Issue 11, p. 649 –650
  • DOI:  10.1049/el:19880439
  • Type: Article
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  • p. 649 –650 (2)
    We demonstrate a bidirectional lightwave distribution system that uses subcarrier multiplexing to transmit data to eight nodes from a single head-end laser. Data for each node (180 Mbit/s) and return data (45 Mbit/s digital video) are transmitted as FSK subcarriers, between 2.5 and 5.0 GHz. Penalties from laser nonlinearities, interchannel interference or bidirectional transmission are negligible.
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Constructing new perfect binary arrays
Resonantly enhanced two-wave mixing via population pulsations in semiconductor laser amplifiers
Radiation characteristics of a waveguide-excited short backfire-fed parabolic reflector operating in Q-band
  • Author(s): P.S. Kooi ; M.S. Leong ; Chandra
  • Source: Electronics Letters, Volume 24, Issue 11, p. 653 –654
  • DOI:  10.1049/el:19880442
  • Type: Article
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  • p. 653 –654 (2)
    The letter presents measured results at 31–38 GHz of the radiation characteristics of a 0.252 m diameter parabolic dish fed at the prime focus by a short backfire antenna. The feed consists of an experimentally optimised design of a short backfire antenna, having a conical main reflector of 15° slant angle. The measured radiation patterns of the reflector system generally agree quite well with the prediction based on aperture field integration.
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Novel sampling technique for digital video demultiplexing, descrambling and channel selection
Gain enhancement of microstrip antennas with overlaying parasitic directors
Evaluation of scalar products of repeated integrals of a function with rational Laplace transform
New adaptive normalised lattice algorithm for recursive filters
Microwave lowpass filters using hybrid uniplanar structures
Four-port fibre-optic ring resonator
Straightforward derivation of boundary conditions on sheet simulating an anisotropic thin layer
Gabor's expansion of an aperture field in exponential elementary beams
Monolithic millimetre-wave oscillator using a transmission line periodically loaded by QWITT diodes
  • Author(s): V.P. Kesan ; A. Mortazawi ; D.P. Neikirk ; T. Itoh
  • Source: Electronics Letters, Volume 24, Issue 11, p. 666 –667
  • DOI:  10.1049/el:19880451
  • Type: Article
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  • p. 666 –667 (2)
    A small-signal analysis of a travelling-wave structure implemented by periodically loading a parallel-plate waveguide with either resonant tunnelling or QWITT diodes is presented. A small-signal equivalent circuit is used to determine the diode impedance as a function of frequency. The periodicity of the structure, i.e. the distance between adjacent diodes, determines the oscillation (resonant) frequency of the circuit. The analysis shows that change in the oscillation frequency through variation in the design width and thickness of the waveguide is minimal. The physical dimensions of the waveguide facilitate monolithic fabrication of the oscillator circuit.
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Multigigabit multiplexer design
Measurement of a modulated DFB laser spectrum using gated delayed self-homodyne technique
Blank and burst transmission of data over active speech channels
  • Author(s): W.C. Wong  and  D.J. Goodman
  • Source: Electronics Letters, Volume 24, Issue 11, p. 670 –672
  • DOI:  10.1049/el:19880454
  • Type: Article
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  • p. 670 –672 (3)
    To increase the capacity of blank and burst transmission of control information in cellular communication systems, we explore the application of a speech segment reconstruction technique. The transmitter selects a blanking interval on the basis of a segment classification measure, while the receiver replaces the missing speech with an estimate based on previously received speech. Using this approach, approximately 3.2 data bursts per second, each lasting 16 ms, may be sent without degrading speech quality.
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Novel single-mode, grating WDM device based network
Field-effect transistor with diphthalocyanine thin film
Bidirectional beam propagation method
Jitter accumulation in a simulated 591.2 Mbit/s, 6000 km optical transmission system
Image registration using Fermat transforms
  • Author(s): C. Morandi ; F. Piazza ; A. Dolcetti
  • Source: Electronics Letters, Volume 24, Issue 11, p. 678 –680
  • DOI:  10.1049/el:19880459
  • Type: Article
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  • p. 678 –680 (3)
    Binary boundary maps are obtained by edge detection, then their relative translation is determined by conventional crosscorrelation computed by Fermat transform. Use of boundary maps emphasises edges and sharp discontinuities, while rejecting disturbances related to nonuniform illumination, thus avoiding the costly normalisation step. Use of integer arithmetic allows significant savings in computatio
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Improved cavity model parameters for calculation of resonant frequency of rectangular microstrip antennas
Eleven-bit parity generator with a single, vertically integrated resonant tunnelling device
  • Author(s): A.A. Lakhani ; R.C. Potter ; H.S. Hier
  • Source: Electronics Letters, Volume 24, Issue 11, p. 681 –683
  • DOI:  10.1049/el:19880461
  • Type: Article
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  • p. 681 –683 (3)
    A vertically integrated diode (VID) with five negative differential resistance regions has been developed by stacking five resonant tunnelling structures. This device can be used for processing both analogue and digital signals. An 11-bit parity checker was demonstrated using the VID. In this approach, a single device replaced a large number of exclusive-OR gates in a conventional parity checker.
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Linear resonator in photorefractive BSO with two pump beams
Effect of external cavity semiconductor laser phase noise on a DPSK heterodyne optical receiver
Ge-Si/Si infra-red, zone-folded superlattice detectors
Barrier height enhancement of InP-based n-Ga0.47In0.53As Schottky-barrier diodes grown by molecular beam epitaxy
  • Author(s): J.H. Kim ; S.S. Li ; L. Figueroa
  • Source: Electronics Letters, Volume 24, Issue 11, p. 687 –689
  • DOI:  10.1049/el:19880465
  • Type: Article
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  • p. 687 –689 (3)
    Barrier height enhancement of an InP-based p+n-Ga0.47In0.53As Schottky diode grown by MBE has been demonstrated for infra-red photodetector applications. A barrier height of 0.35eV for n-Ga0.47In0.53As Schottky barrier diodes, was increased to the effective barrier height of 0.55eV, with a p+-Ga0.47In0.53As surface layer of 30 nm thick. The results show a reverse leakage current density of 1.5 × 10−3 A/cm2 and a junction capacitance of 0.3 pF, which are comparable to those of p-Ga0.47In0.53As Schottkybarrier diodes at a reverse bias voltage of 5 V.
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Demonstration of an eight-element time-division multiplexed interferometric fibre sensor array
Silicon on quartz by solid-state diffusion bonding (SSDB) technology
  • Author(s): X.-L. Xu ; J. Zhan ; Q.-Y. Tong
  • Source: Electronics Letters, Volume 24, Issue 11, p. 691 –692
  • DOI:  10.1049/el:19880467
  • Type: Article
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  • p. 691 –692 (2)
    Silicon wafer and quartz have been successfully bonded together by a two-step thermal treatment process. SIMS measurements shows that after molecular surface activated solvent treatment, the amount of OH on the silicon or quartz surface, which is essential to the first step (low-temperature) bonding strength, is one order of magnitude higher than that on the original silicon or quartz surface. After a high-temperature (850–1250°C) solid-state diffusion process, the bonding strength between silicon and quartz is greatly increased to 150–185 kg/cm2. The material and electrical properties of the silicon on quartz substrate compares favourably with those of the bulk silicon wafer.
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Modelling of CSMA/CA protocol by simulation
Continuous multidestination ARQ schemes for high error-rate channels
High-speed 1.3 μm GaInAsP p-substrate buried-crescent lasers with semi-insulating Fe/Ti-doped InP current blocking layers
  • Author(s): C.E. Zah ; C. Caneau ; S.G. Menocal ; F. Favire ; T.P. Lee ; A.G. Dentai ; C.H. Joyner
  • Source: Electronics Letters, Volume 24, Issue 11, p. 695 –697
  • DOI:  10.1049/el:19880470
  • Type: Article
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  • p. 695 –697 (3)
    High-speed 1.3 μm GaInAsP buried-crescent lasers were made with a MOVPE-grown semi-insulating Fe/Ti-doped InP current-blocking layer on p-InP substrate. Ti, a deeplevel donor, was used to compensate Zn outdiffusion from the buffer layer during the LPE regrowth. Devices with broad area contacts had a modulation bandwidth of 11 GHz, a low threshold current of 11 mA, and an output power of 23 mW per facet.
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High-frequency (>1 MHz) convertors for induction heating applications
Reproducible fabrication of AlGaAs/GaAs circular buried heterostructure (CBH) surface-emitting lasers with low thresholds
Performance of a voice/data multiplexer with ARQ schemes
DC and microwave characteristics of modulation doped Ga0.47In0.53As/InP HFET
  • Author(s): A. Shahar ; M.D. Feuer ; U. Koren ; B.I. Miller
  • Source: Electronics Letters, Volume 24, Issue 11, p. 702 –703
  • DOI:  10.1049/el:19880474
  • Type: Article
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  • p. 702 –703 (2)
    The DC and microwave performance of modulation doped GaInAs/InP HFETs (heterostructure FET), grown by atmospheric pressure organometallic vapour phase epitaxy is reported. An extrinsic transconductance of 300 mS/mm and a best value of the cutoff frequency, Fr = 14.1 GHz in a 1.5 μm gate device was measured at room temperature. Improved performance of the Schottky gate device is obtained using an Au gate on the InP/GaInAs heterostructure layers. A low access resistance of 3 Ωmm is obtained using a self-aligned technique with high conductivity n+-GaInAs top layers. ty n+-GaInAs top layers.
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Seasonal variation of crosspolarisation statistics observed at CS-2 experimental Earth station
4.8 kbit/s data transmission over 16 kbit/s digital mobile radio channel
Fast CELP coder using Givens bidiagonalisation
GaAs MESFETs with nonalloyed ohmic contacts: technology and performance
Samarium3+-doped glass laser operating at 651 nm
  • Author(s): M.C. Farries ; P.R. Morkel ; J.E. Townsend
  • Source: Electronics Letters, Volume 24, Issue 11, p. 709 –711
  • DOI:  10.1049/el:19880479
  • Type: Article
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  • p. 709 –711 (3)
    Laser emission has been observed in a samarium3+-doped silica optical fibre in a Fabry-Perot-type laser cavity. The emission is centred on 651 nm and corresponds to stimulated transitions from the 4G5/2 level to the 6H9/2 level. The fluorescence and absorption associated with the metastable level are seen to be unusually narrow (3nm FWHM) for a trivalent rare earth in a disordered glass structure. The laser has operated in CW and Q-switched modes when pumped with 488 nm light at room temperature.
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Automatic edge extraction using locally adaptive threshold
  • Author(s): G.S. Jung  and  R.-H. Park
  • Source: Electronics Letters, Volume 24, Issue 11, p. 711 –712
  • DOI:  10.1049/el:19880480
  • Type: Article
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  • p. 711 –712 (2)
    We describe an automatic edge extraction algorithm using a new edge operator called the EK edge operator, and a locally adaptive threshold subject to brightness and gradient value in a picture. The proposed algorithm is capable of extracting one-pixel-thick edges and giving a rather pleasing representation of the original grey-level picture. This algorithm is compared to the well known Sobel gradient operator and Keskes' zero-crossing operator.
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Performance analysis of a voice/data multiplexer for a nonfixed number of voice calls
Comment: Existence of one-dimensional perfect binary arrays
Through-wafer optical interconnection coupling characteristics
  • Author(s): L.A. Hornak
  • Source: Electronics Letters, Volume 24, Issue 11, p. 714 –715
  • DOI:  10.1049/el:19880483
  • Type: Article
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  • p. 714 –715 (2)
    Both the optical coupling and resulting optical crosstalk characteristics for LED-based through-wafer optical interconnections have been measured within a simulated stacked wafer environment. Using integrated SiO2 Fresnel phase plate lens arrays, a nearly 4:1 improvement in received signal was noted over the configuration without lenses. Interchannel crosstalk measurements indicate that from an optical standpoint, high interconnect densities (250 μm pitch) are obtainable with reasonable noise margins over a range of distances of interest for stacked wafer architectures.
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CPFSK coherent optical receivers: impact of IF bandwidth and laser phase noise
  • Author(s): G. Jacobsen  and  L.G. Kazovsky
  • Source: Electronics Letters, Volume 24, Issue 11, p. 715 –717
  • DOI:  10.1049/el:19880484
  • Type: Article
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  • p. 715 –717 (3)
    A detailed theoretical model for narrowband CPFSK receivers is presented. It accounts for the influence of IF bandwidth on the signal voltage, non-Gaussian statistics of the output noise, correlation between noise samples stemming from limited IF bandwidth, and the impact of laser phase noise. It is found that the IF bandwidth needed to avoid intersymbol interference is 2.2 times the bit rate for a modulation index of 1; it is higher for other modulation index values. The bit error ratio is within 1 dB of the shot noise limit for the modulation index of 1.
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High-current, planar-doped pseudomorphic hemts Ga0.4In0.6As/Al0.48In0.52As HEMTs
  • Author(s): A. Fathimulla ; H. Hier ; J. Abrahams
  • Source: Electronics Letters, Volume 24, Issue 11, p. 717 –718
  • DOI:  10.1049/el:19880485
  • Type: Article
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  • p. 717 –718 (2)
    The letter reports the first successful growth and fabrication of high-performance, planar-doped pseudomorphic GaInAs/AlInAs HEMTs. Hall mobilities as high as 11900cm2/Vs (300 K) with sheet-electron concentrations of 2.4 × 1012cm−2 were measured for the heterostructures. A drain-saturation current of 1 A/mm, a transconductance of 420mS/mm, and an extrapolated f1 of 64 GHz were achieved in a 0.5 μm gate-length HEMT.
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Comment: Fundamental error of recent coupled mode formulations
Reply: Coupled mode theory neglects polarisation phenomena

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