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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 26, Issue 9, 26 April 1990

Volumes & issues:

Volume 26, Issue 9

26 April 1990

Switched-capacitor lowpass filters based on recursive running sum cells
ATM access through a passive optical network
Impedance of TEM cells with equipment under test
Effective mapping of continuous-time controllers to their discrete equivalents
Suppression of InP substrate degradation by hydrogen plasma caused by the presence of phosphorus vapour
  • Author(s): R. Schütz ; K. Matsushita ; H.L. Hartnagel ; J.Y. Longere ; S.K. Krawczyk
  • Source: Electronics Letters, Volume 26, Issue 9, p. 564 –566
  • DOI:  10.1049/el:19900369
  • Type: Article
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  • p. 564 –566 (3)
    It is demonstrated that the degradation of InP substrates in a hydrogen plasma can be prevented by the introduction of phosphorus vapour into the reaction chamber. The results obtained, using standard surface analysis techniques and photoluminescence depth profiling, indicate that the stoichiometry of the InP surface region can be preserved and the number of P-vacancies which diffuse into the bulk drastically reduced.
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2.488 Gbit/s transmission experiment at 1550 nm over 153 km standard single-mode fibre
600 μm/min laser-induced nonthermal etching of GaAs in an HF solution
  • Author(s): A.E. Willner ; D.V. Podlesnik ; R.M. Osgood
  • Source: Electronics Letters, Volume 26, Issue 9, p. 568 –569
  • DOI:  10.1049/el:19900371
  • Type: Article
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  • p. 568 –569 (2)
    600 μm/min room-temperature photochemical aqueous etching of n-type GaAs in an HF acid based solution is reported. This rapid etch rate is achieved under UV illumination and represents more than an order of magnitude enhancement over previously reported results for solutions containing no HF acid. The process is used to fabricate deep, large-area structures such as trench formations and through-wafer via holes which would otherwise be impractical with slower direct-write techniques.
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Linewidth enhancement in distributed-feedback semiconductor lasers
Perturbation analysis of finlines containing anisotropic media
  • Author(s): P.V. Ramakrishna  and  D. Chadha
  • Source: Electronics Letters, Volume 26, Issue 9, p. 571 –572
  • DOI:  10.1049/el:19900373
  • Type: Article
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  • p. 571 –572 (2)
    The simple perturbation method is applied to obtain the propagation characteristics of finlines loaded with anisotropic material. Starting from the analysis of a finline on isotropic dielectric substrate, we obtain the propagation constants of finlines having dielectric anisotropy in the substrate and finlines containing magnetised ferrite. The main feature of the perturbation method is its simplicity. Since the anisotropies encountered in practice are small deviations about some mean isotropic value, the results obtained show good agreement with those obtained using the rigorous methods reported in the literature.
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Towards a coherent optical free-space communication system
High performance single mode OTDR using coherent detection and fibre amplifiers
  • Author(s): Y. Koyamada  and  H. Nakamoto
  • Source: Electronics Letters, Volume 26, Issue 9, p. 573 –575
  • DOI:  10.1049/el:19900375
  • Type: Article
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  • p. 573 –575 (3)
    A high performance single mode OTDR has been constructed at 1.55 μm using a DFB laser diode, laser diode pumped fibre amplifiers and a coherent detector, all suited to integration into a robust and portable instrument. A dynamic range of 33 dB has been attained with 1 μs launch pulses, 1 MHz receiver bandwidth and 104 integrations. This result represents an increase of about 13 dB in performance over the standard version of the OTDR using a laser diode as a light source. It is comparable to the best previously reported value attained using a high power glass laser and a cooled detector.
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Motion compensated sequence coding using image pyramids
Integrated dielectric wavelength filters on InGaAs PIN photodetectors
High resolution laser LIDAR utilising two-section distributed feedback semiconductor laser as a coherent source
  • Author(s): E.C. Burrows  and  K.-Y. Liou
  • Source: Electronics Letters, Volume 26, Issue 9, p. 577 –579
  • DOI:  10.1049/el:19900378
  • Type: Article
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  • p. 577 –579 (3)
    An air-spaced coherent LIDAR (light detection and ranging) employing a two-section distributed feedback (DFB) injection laser is demonstrated. The relative distance of a mirror target was detected with 0.1 μm resolution. The absolute distance of a diffuse target was measured with 1 cm accuracy. These results indicate that semiconductor lasers developed for communication systems may be useful for sensing applications such as robotic vision, surface profiling and automated fabrication.
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Tunable CW fibre Raman ring laser centred at 1.41 μm
Dependence of propagation loss of magnetostatic forward volume waves on device parameters
  • Author(s): M. Yamaguchi ; K. Hashimoto ; H. Kaneda
  • Source: Electronics Letters, Volume 26, Issue 9, p. 581 –582
  • DOI:  10.1049/el:19900380
  • Type: Article
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  • p. 581 –582 (2)
    It is shown that for magnctostatic forward volume waves (MSFVW) the propagation loss depends on device parameters such as thickness of magnetic film, MSFVW wavelength, a static magnetic field, etc. The result suggests that when the film thickness is about a quarter of the wavelength and the effective internal field is comparable to or larger than the saturation magnetisation of the film, the propagation loss per wavelength is minimised. Experimental results were in good agreement with this theoretical prediction.
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Novel pipelined serial/parallel multiplier
Reduction of internal current measurements within the failure bounds analogue diagnosis scheme
2.55 μm, 400 Mbit/s transmission experiment with single-mode fluoride optical fibre
Frequency-hopping radio filter design using the DSP16 processor
Error surface analysis of adaptive comb filter
  • Author(s): J.F. Chicharo
  • Source: Electronics Letters, Volume 26, Issue 9, p. 587 –589
  • DOI:  10.1049/el:19900385
  • Type: Article
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  • p. 587 –589 (3)
    A minimal parameter infinite-impulse-resonse (IIR) adaptive comb filter model is presented for use in eliminating or retrieving a harmonic series buried in a broadband signal. The adaptive comb filter estimates and tracks the fundamental frequency of the harmonic series. Error surface analysis is carried out to obtain the convergence characteristics of the proposed comb filter. Special pole and zero constraints are introduced which enhance the filter performance. Results show that although the error surface is multimodal its performance is excellent for a certain class of filtering applications.
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Autocorrelation at 1.3–1.5 μm using POM crystal
Double-heterostructure AlGaAs/GaAs lasers grown on the mesas of trenched Si substrate by molecular beam epitaxy
  • Author(s): X. Liu ; H.P. Lee ; S. Wang
  • Source: Electronics Letters, Volume 26, Issue 9, p. 590 –592
  • DOI:  10.1049/el:19900387
  • Type: Article
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  • p. 590 –592 (3)
    The growth and device characteristics of stripe Al0.26Ga0.74As/GaAs double-heterostructure lasers grown on mesas of trenched Si by MBE is reported. The TE and TM modes lase at different injection levels depending on the laser stripe width. This behaviour is attributed to the variation of the residual thermal stress present in the laser structures as a function of stripe width. By comparing the polarisations of the laser radiations from a narrow and broad stripe laser, it is found that a narrow mesa is effective in reducing the residual thermal stress.
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Medium access control protocol for the integration of voice/data on a local area network
Comment: Slotted ALOHA radio networks with PSK modulation in Rayleigh fading channels
Reply: Slotted ALOHA radio networks with PSK modulation in Rayleigh fading channels
Balanced 3×3 port phase diversity receiver with reduced impact of thermal noise
Rain rate measurements in Indonesia
Simple method for calibration of stress-induced birefringence in fibres with arbitrary structures
CW diode-pumped operation of 1.97 μm thulium-doped fluorozirconate fibre laser
Delta doped tunnel diode: a new negative differential resistance device
  • Author(s): J.M.A. Gilman  and  A.G. O'Neill
  • Source: Electronics Letters, Volume 26, Issue 9, p. 601 –602
  • DOI:  10.1049/el:19900395
  • Type: Article
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  • p. 601 –602 (2)
    A novel tunnel diode is proposed. Modulation doping is used to define a two dimensional electron or hole gas on either side of a p–n junction tunnelling barrier. The additional parameter of doping spike separation enables a wide range of I–V characteristics to be selected. This leads to a decoupling of the current peak and corresponding voltage. Improvements in current density and speed are predicted.
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9.5 GHz bandwidth HBT gain controllable amplifier IC with an amplitude detection circuit
Radio propagation over trapezoidal plateau with sloping front face
7203-user WDM broadcast network employing one erbium-doped fibre power amplifier
  • Author(s): A.M. Hill ; D.B. Payne ; K.J. Blyth ; D.S. Forrester ; J.W. Arkwright ; R Wyatt ; J.F. Massicott ; R.A. Lobbett ; P. Smith ; T.G. Hodgkinson
  • Source: Electronics Letters, Volume 26, Issue 9, p. 605 –607
  • DOI:  10.1049/el:19900398
  • Type: Article
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  • p. 605 –607 (3)
    The broadcasting of 10 wavelength channels over 29.6 km of fibre in a passive splitting network to 7203 potential user terminals, using a single broadband Er-doped fibre power amplifier is reported. Wavelength selection was achieved by a tunable grating filter. A total broadcast network capacity of 2560 Tbit/s km user has been achieved with a single amplifier providing all the required power.
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Calculation of phase shift sensitivity in polarimetric fibre sensors
Measurement and theory of mode hopping in external cavity lasers
AC Josephson effect in superconducting niobium nitride tunnel junctions at up to 2.5 THz
  • Author(s): M.C. Wicks ; P.R. Haycocks ; T. Hori
  • Source: Electronics Letters, Volume 26, Issue 9, p. 610 –612
  • DOI:  10.1049/el:19900401
  • Type: Article
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  • p. 610 –612 (3)
    Shapiro steps have been observed in the I–V characteristics of an NbN tunnel junction illuminated with radiation from an optically pumped far infrared laser. The maximum operating frequency which produced an observable Shapiro step was 2.53 THz. This is a four-fold increase over that previously reported for a thin film Josephson junction. Clear steps were also produced by various laser lines in the frequency range 0.6–1.8 THz.
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Noise behaviour of InAlAs/GaInAs MSM photodetectors
  • Author(s): H. Schumacher ; J.B.D. Soole ; H.P. Leblanc ; R. Bhat ; M.A. Koza
  • Source: Electronics Letters, Volume 26, Issue 9, p. 612 –614
  • DOI:  10.1049/el:19900402
  • Type: Article
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  • p. 612 –614 (3)
    Planar metal-semiconductor-metal (MSM) photodetectors are becoming increasingly popular for use in optoelectronic integrated circuits. A GalnAs absorption layer is used with a thin surface layer of a semiconductor and a higher Schottky barrier to limit the dark current for applications in the 1.3 – 1.6 μm fibre bands. Planar photodetectors are prone to lowfrequency noise because of traps at interfaces, and this may deteriorate the optical receiver performance. We have investigated the noise in low-leakage AlInAs/GaInAs detectors and find that the excess low frequency noise is limited to frequencies < 1 MHz under normal operating conditions.
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Fabrication and optical characterisation of first order DFB GaInP/AlGaInP laser structures at 639 nm

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