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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 27, Issue 8, 11 April 1991

Volumes & issues:

Volume 27, Issue 8

11 April 1991

Year-to-year variability and worst-month statistics of long-term rain rate measurements in Germany
AlGaInAs/AlGaAs SSQW GRINSCH lasers for the wavelength region between 800 and 870 nm
  • Author(s): L. Buydens ; P. Demeester ; M. van ackere ; P. van daele
  • Source: Electronics Letters, Volume 27, Issue 8, p. 618 –620
  • DOI:  10.1049/el:19910388
  • Type: Article
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  • p. 618 –620 (3)
    A semiconductor laser is proposed which has an optical active region consisting of an 8 nm thick Al0.20 Ga0.65 In0.15As/Al0.20Ga0.30As strained single quantum well. The spectral emission peak of this quantum well is situated between 814 and 818 nm. The optical confinement is achieved using a standard graded refractive index separate confinement heterostructure optimised for the emission wavelength of the quantum well. Preliminary results show these lasers to have a threshold current of 18 mA.
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Carrier-induced group-velocity dispersion and pulse compression in semiconductor laser amplifiers
  • Author(s): G.P. Agrawal
  • Source: Electronics Letters, Volume 27, Issue 8, p. 620 –621
  • DOI:  10.1049/el:19910389
  • Type: Article
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  • p. 620 –621 (2)
    The effect of gain dispersion on pulse amplification in semiconductor laser amplifiers is investigated theoretically. A novel phenomenon, referred to as carrier-induced group-velocity dispersion, is shown to influence considerably the amplified pulse. Chirped input pulses are predicted to be compressed in the presence of carrier-induced dispersion even when the amplifier operates far below saturation. The dependence of the compression factor on device parameters such as the pulse width, the amplifier gain, and the linewidth enhancement factor are studied using a simple analytic model. The results are important for optical communication systems as they imply that semiconductor laser amplifiers can be used to compensate simultaneously for the effects of both fibre loss and fibre dispersion when used as in-line amplifiers.
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Polarisation-induced visibility limits in interferometric fibre-optic sensor arrays
  • Author(s): Y.S. Boger  and  M. Tur
  • Source: Electronics Letters, Volume 27, Issue 8, p. 622 –623
  • DOI:  10.1049/el:19910390
  • Type: Article
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  • p. 622 –623 (2)
    Polarisation-induced fading is analysed in Mach–Zehnder type interferometric fibre-optic sensor arrays. Given a sensor array configuration and the polarisation properties of individual elements, a procedure is presented to find an optimal input state of polarisation which maximises overall sensor visibility. It is shown that for both serial and parallel arrays with N sensor elements, the visibility of the worst-case sensor configuration can be maximised to a value of sin (π/2N).
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Coherent detection of multiamplitude MSK under imperfect phase synchronisation
  • Author(s): V. Gonçalves ; A. Gusmão ; N. Esteves
  • Source: Electronics Letters, Volume 27, Issue 8, p. 623 –625
  • DOI:  10.1049/el:19910391
  • Type: Article
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  • p. 623 –625 (3)
    Simple formulas for the BER performance achieved through coherent detection of MAMSK signals, under a carrier phase error, are presented. It is shown that MAMSK schemes are much less sensitive to imperfect carrier recovery than the corresponding QAM schemes, this advantage being especially clear when serial detection is employed. Possible applications to future TDMA satellite systems are emphasised.
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Hidden Markov models with duration-dependent state transition probabilities
  • Author(s): S.V. Vaseghi
  • Source: Electronics Letters, Volume 27, Issue 8, p. 625 –626
  • DOI:  10.1049/el:19910392
  • Type: Article
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  • p. 625 –626 (2)
    A new method is proposed for incorporation of duration knowledge in the form of duration-dependent state transition probabilities in a left-right hidden Markov model. Duration-dependent transition probabilities are derived from integration of histograms of the state durations. The model re-estimation process becomes one of obtaining a new segmentation from which a new set of state and observation probabilities are derived.
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Amplification and lasing at 1.3 μm in praseodymium-doped fluorozirconate fibres
  • Author(s): Y. Durteste ; M. Monerie ; J.Y. Allain ; H. Poignant
  • Source: Electronics Letters, Volume 27, Issue 8, p. 626 –628
  • DOI:  10.1049/el:19910393
  • Type: Article
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  • p. 626 –628 (3)
    Light emission from the 1G4 → 3H5 transition around 1.3 μm of Pr3+ has been studied in fluoride glass (ZBLAN) fibres. Pumping at 1064 nm yields extracted laser power of a few mW at 1.294 μm. Gain curves centred at 1.295 μm have been obtained, with gross gains of more than 15dB at 1.319 μm. Changes of the output ASE with pumping conditions are explained by excited state absorption or energy transfer from the 1G4 upper level of the transition.
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Amplification at 1.3 μm in a Pr3+-doped single-mode fluorozirconate fibre
BER performance owing to random FM noise for QDPSK mobile radio with diversity reception
DC and RF characteristics of InAlAs/InGaAs dual-gate TEGFETs
  • Author(s): F. Gueissaz ; R. Houdré ; M. Ilegems
  • Source: Electronics Letters, Volume 27, Issue 8, p. 631 –632
  • DOI:  10.1049/el:19910396
  • Type: Article
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  • p. 631 –632 (2)
    DC and microwave measurements on 0.7 μm single-gate (SG) and dual-gate (DG) In0.52Al0.48As/In0.53Ga0.47As planar doped two-dimensional electron gas field-effect transistors (TEGFETs) are reported. The DG devices show a large increase of the gm to gD ratios, which are as high as 100 at gm = 380mS/mm, compared with 12 at 420mS/mm for the single gate (SG) devices on the same chip, as well as 6dB improvement in the RF power gain compared with their SG counterparts.
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Analysis of simultaneous digital and analogue signal transmissions in a coherent optical subcarrier multiplexed system
  • Author(s): J. Wu ; H.-W. Tsao ; K.-P. Ho ; Y.-H. Lee
  • Source: Electronics Letters, Volume 27, Issue 8, p. 632 –634
  • DOI:  10.1049/el:19910397
  • Type: Article
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  • p. 632 –634 (3)
    The performance of the coherent subcarrier multiplexed system with mixed digital and analogue signals is analysed. The result shows that the performance of the digital channels in this system may be better than the pure digital system if the modulation index of the analogue channel is less than half of the modulation index of the digital channel. It is predicted that the system will have a 14dB improvement over the corresponding intensity modulation/direct detection system.
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Product and interleaving of anticodes
  • Author(s): V.C. Da Rocha  and  M.M. Campello de Souza
  • Source: Electronics Letters, Volume 27, Issue 8, p. 634 –636
  • DOI:  10.1049/el:19910398
  • Type: Article
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  • p. 634 –636 (3)
    Two techniques are presented for constructing new anticodes from known anticodes, namely the product and interleaving of anticodes. The product of anticodes (m1, k1, δ1,) and (m2, k2, δ2) produces an (m1m2, k1k2, δ) anticode, where δ1δ2 ≤ δ≤ min [m1δ2, m2δ1]. Interleaving of degree λ of an (m, k, δ) anticode produces an (mλ, kλ, δλ) anticode. The efficiency of these constructions is examined in terms of the Griesmer bound for the binary case. As a result a rule is derived for selecting anticodes which can be efficiently combined either by product or interleaving.
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28 Gbit/s selector IC using AlGaAs/GaAs HBTs
Nearly bird's beak-free local oxidation technology for controlled dielectric formation in deep silicon trenches
  • Author(s): K. Shenai
  • Source: Electronics Letters, Volume 27, Issue 8, p. 637 –639
  • DOI:  10.1049/el:19910400
  • Type: Article
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  • p. 637 –639 (3)
    Silicon deep trench isolation technology using local oxidation is reported. Scaled, high-density trench capacitors were fabricated with varying trench aspect ratios. Nearly bird's beak-free local oxidation resulted in a controlled growth of silicon dioxide on the trench bottom surfaces and significantly improved the trench gate MOS isolation characteristics. Detailed MOS capacitance measurements were performed and wafer yield in excess of 90% was demonstrated across 4 inch diameter silicon wafers.
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Stray-insensitive switched-capacitor sample-delay-hold buffers for video frequency applications
Error probability of coherent PSK and FSK systems with multiple cochannel interferences
Modelling of sinusoidal function for nonlinear signal processing applications
Design of fibre-matched InP waveguides by scalar transverse field formulation
Narrow-linewidth strained-layer 1.5 μm multiquantum well distributed feedback lasers
  • Author(s): S.J. Wang ; Y. Twu ; T. Tanbun-Ek ; R.A. Logan ; N.K. Dutta ; A.B. Piccirilli
  • Source: Electronics Letters, Volume 27, Issue 8, p. 645 –647
  • DOI:  10.1049/el:19910405
  • Type: Article
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  • p. 645 –647 (3)
    The performance characteristics of narrow-linewidth strained-layer 1.5 μm multi-quantum-well distributed feedback (MQW-DFB) lasers are presented. Measured linewidth as low as 3.5 MHz has been observed for one of the 250 μm long devices at 14.4 mW output. Under 1.7 Gbit/s 1.0, 1.0, … pattern signal modulation, the lasers have 20 dB down full width chirp in the range of 5–6 Å for the off state at 0.8Ith. The chirp widths are about half of those of bulk-active DFB lasers. A 1.7Gbit/s amplitude-shift-keying transmission experiment using one of the low-chirp lasers has been demonstrated. The transmission over 60 km of standard fibre only result in a 0.8 dB dispersion power penalty and has a receiver sensitivity of −36.2 dBm at BER = 10-9.
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Resonant-tunnelling diode oscillator using a slot-coupled quasioptical open resonator
  • Author(s): K.D. Stephan ; E.R. Brown ; C.D. Parker ; W.D. Goodhue ; C.L. Chen ; T.C.L.G. Sollner
  • Source: Electronics Letters, Volume 27, Issue 8, p. 647 –649
  • DOI:  10.1049/el:19910406
  • Type: Article
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  • p. 647 –649 (3)
    A resonant-tunnelling diode has oscillated at X-band frequencies in a microwave circuit consisting of a slot antenna coupled to a semiconfocal open resonator. Coupling between the open resonator and the slot oscillator improves the noise-to-carrier ratio by about 36 dB relative to that of the slot oscillator alone in the 100–200 kHz range. A circuit operating near 10GHz has been designed as a scale model for millimetre- and submillimetre-wave applications.
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Chirp compensation capability of a semiconductor laser amplifier
  • Author(s): C.R. Medeiros  and  J.J. O'Reilly
  • Source: Electronics Letters, Volume 27, Issue 8, p. 649 –650
  • DOI:  10.1049/el:19910407
  • Type: Article
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  • p. 649 –650 (2)
    Performance improvement is reported resulting from incorporating a semiconductor laser amplifier (SLA) as a post-transmitter-amplifier in long-haul directly modulated optical systems operating in the 1.5 μm region. This improvement arises from reduction of the chirp produced by the semiconductor laser as the signal passes through the SLA. Eye closure penalty improvements in excess of 5 dB are observed for an illustrative long-haul 4.8 Gbit/s system.
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Operational floating conveyor
  • Author(s): C. Toumazou ; A. Payne ; F.J. Lidgey
  • Source: Electronics Letters, Volume 27, Issue 8, p. 651 –652
  • DOI:  10.1049/el:19910408
  • Type: Article
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  • p. 651 –652 (2)
    A new versatile analogue building block is described, termed an operational floating conveyor (OFC). The OFC has similar transmission properties to the current conveyor and current-feedback operational amplifier, but with a differential current output which allows accurate output current sampling. This feature improves circuit building block versatility and allows accurate closed loop current amplifiers and current convenors to be realised, including a closed loop current conveyor.
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New technique for estimation of farfield from near-zone phaseless data
  • Author(s): T. Isernia ; R. Pierri ; G. Leone
  • Source: Electronics Letters, Volume 27, Issue 8, p. 652 –654
  • DOI:  10.1049/el:19910409
  • Type: Article
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  • p. 652 –654 (3)
    A new method for the estimation of the far field from two amplitude distributions in near zone is presented. The crucial point of the proposed approach relies on the choice of an appropriate function of the data, which is minimised in order to find the solution. It turns out that, although the problem is nonlinear, the global minimum can be found efficiently by a Newton-like minimisation procedure.
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Vectorial beam-propagation method for integrated optics
Linear tunable resistance circuit using gallium arsenide MESFETs
Fabrication and assessment of a D-fibre polarisation splitter
Optical switching in an asymmetric Fabry–Perot with high contrast ratio and very low insertion loss
High-power operation of 630 nm-band transverse-mode stabilised AlGaInP laser diodes with current-blocking region near facets
  • Author(s): H. Hamada ; M. Shono ; S. Honda ; R. Hiroyama ; K. Matsukawa ; K. Yodoshi ; T. Yamaguchi
  • Source: Electronics Letters, Volume 27, Issue 8, p. 661 –662
  • DOI:  10.1049/el:19910414
  • Type: Article
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  • p. 661 –662 (2)
    High-power type AlGaInP laser diodes (λL = 635 nm) with the current-blocking region near the facets have been successfully fabricated for the first time, by MOCVD using the (100) GaAs substrates with a misorientation of 5° towards the (100) direction. The maximum continuous wave output power was achieved with about 33 mW at 20°C. Fundamental transverse-mode operation was obtained up to 20 mW.
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20 Gbit/s AlGaAs/GaAs-HBT 2:1 selector and decision ICs
Excitation characteristics of fundamental mode in tapered slab waveguides with nonlinear cladding
Efficient systolic implementation of complex digital filters
Accurate charge control model for MODFET including subthreshold region
Reduction of distortion in analogue modulated semiconductor lasers by feedforward compensation
Buffer requirements for ATM switches with multiserver output queues
  • Author(s): H. Bruneel  and  B. Steyaert
  • Source: Electronics Letters, Volume 27, Issue 8, p. 671 –673
  • DOI:  10.1049/el:19910420
  • Type: Article
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  • p. 671 –673 (3)
    A fast packet switch with shared-memory output queueing is considered, in which each destination group contains multiple-output links. An approximate calculation technique is presented to determine the overflow probability of the shared buffer of such a switch. Exact analytic results are also obtained for the mean buffer contents. Using the results of the analysis, a comparison of the buffer requirements for various switch structures is made, showing that grouping the output links may be quite advantageous.
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Models of round-off noise in second-order sigma–delta modulators
  • Author(s): J.H. Blythe
  • Source: Electronics Letters, Volume 27, Issue 8, p. 673 –675
  • DOI:  10.1049/el:19910421
  • Type: Article
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  • p. 673 –675 (3)
    Current theories of quantisation noise are approximate for second-order sigma–delta modulators which contain a one-bit A/D. A method is suggested which gives a better approximation, based on the behaviour of the system in the absence of an input. In discrete variable systems, the output can follow one of a set of closed cycles, and the suggestion is that the average behaviour of the set of closed cycles is the required approximation. A two-dimensional invariant form is found for continuous variable systems, which gives the corresponding approximation.
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Maximum flat digital differentiator
Two-dimensional addressing scheme for digital signal processors
  • Author(s): S. Srinivasan ; A. Singh ; S.S. Gill
  • Source: Electronics Letters, Volume 27, Issue 8, p. 677 –679
  • DOI:  10.1049/el:19910423
  • Type: Article
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  • p. 677 –679 (3)
    Accessing two-dimensional data is an important requirement in many digital-signal-processing algorithms. Examples are matrix operations and two-dimensional fillers. Existing DSP implementations do not address this problem adequately. In this letter, a two-dimensional addressing scheme is proposed for DSPs to simplify the programming effort for two-dimensional algorithms and to speed up the memory access of two-dimensional data.
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Modelling degeneracy for Monte-Carlo simulation of electron transport in GaAs
Performance characteristics of GaInAs/GaAs large optical cavity quantum well lasers
  • Author(s): N.K. Dutta ; J. Lopata ; P.R. Berger ; D.L. Sivco ; A.Y. Cho
  • Source: Electronics Letters, Volume 27, Issue 8, p. 680 –682
  • DOI:  10.1049/el:19910425
  • Type: Article
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  • p. 680 –682 (3)
    The fabrication and performance characteristics of ridge-waveguide GaInAs/GaAs quantum-well lasers with large optical cavity (LOC) designs are reported. As expected, lasers with very large optical cavity have narrow far-field width (22°) perpendicular to the junction. However, due to small confinement factor, they also have higher threshold current (36 mA). The LOC design has been optimised to produce lasers with low threshold current (12 mA), high efficiency (0.45 mW/mA/facet) and narrow far field divergence (32° × 12°). These lasers operate in the fundamental transverse mode to output powers of 130mW/facet.
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Efficient, narrowband LP01↔LP02 mode convertors fabricated in photosensitive fibre: spectral response
Phase noise insensitive coherent optical heterodyne CPFSK receiver with limiter discriminator detector
  • Author(s): X. Zhang  and  P. Jiang
  • Source: Electronics Letters, Volume 27, Issue 8, p. 684 –685
  • DOI:  10.1049/el:19910427
  • Type: Article
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  • p. 684 –685 (2)
    A coherent optical heterodyne CPFSK receiver with a limiter discriminator (LD) detector, which cannot be degraded by the quantum phase noise of lasers when the frequency deviation ratio h is equal to unity is proposed. The receiver can give the same bit error rate as the ideal digital DPSK system. The expression ½ exp (–SNR) can be considered the upper bound of the minimum error rate of CPFSK-LD detector.
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Erratum: Constant beamwidth IIR lowpass filter for data sampled at nonuniform rate

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