Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 18, Issue 12, 10 June 1982
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Volume 18, Issue 12
10 June 1982
Determination of structural parameter variations in single-mode optical fibres by time-domain reflectometry
- Author(s): M.P. Gold and A.H. Hartog
- Source: Electronics Letters, Volume 18, Issue 12, p. 489 –490
- DOI: 10.1049/el:19820332
- Type: Article
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–490
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Backscatter measurements on single-mode fibres reveal apparent changes in local attenuation resulting from backscatter factor variations. The detailed shape of the backscatter waveforms is compared to known variations of fibre parameters.
Low-loss fibre-coupled waveguide directional coupler modulator
- Author(s): R.C. Alferness ; L.L. Buhl ; M.D. Divino
- Source: Electronics Letters, Volume 18, Issue 12, p. 490 –491
- DOI: 10.1049/el:19820333
- Type: Article
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–491
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We report a fibre-coupled Ti: LiNbO3 directional coupler modulator with total fibre-device-fibre insertion loss as low as 1.5 dB for λ=1.32 μm. Low loss has been achieved by using diffusion parameters to give good mode match to the fibre and low propagation loss, an effective SiO2 buffer layer to eliminate electrode loading loss and a directional coupler geometry which minimises the effect of bend loss.
Six-port reflectometer circuit comprising three directional couplers
- Author(s): E.J. Griffin
- Source: Electronics Letters, Volume 18, Issue 12, p. 491 –493
- DOI: 10.1049/el:19820334
- Type: Article
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p.
491
–493
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A six-port reflectometer circuit, assembled from three directional couplers and covering a waveguide passband, is described. Experimental results obtained from a WG 22 wave-guide version show that about 1 mW source power is sufficient for thermistor detectors to be used with the circuit, a level obtainable from millimeter-wave solid-state sources.
Laser mode partition noise in optical wideband transmission links
- Author(s): G. Grosskopf ; L. Küller ; E. Patzak
- Source: Electronics Letters, Volume 18, Issue 12, p. 493 –494
- DOI: 10.1049/el:19820335
- Type: Article
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Laser mode partition noise is an important source of noise in optical transmission systems operating with multimode lasers and dispersive fibres, e.g. single-mode fibres with non-zero material dispersion. The letter describes investigations which confirm the importance of considering laser mode partition noise when practical optical systems are projected. It also gives theoretical estimations and measurement results which are in good agreement, and demonstrates the influence of laser mode partition noise on the transmission quality of an analogue optical system.
Observation of stimulated Brillouin scattering in low-loss silica fibre at 1.3 μm
- Author(s): D. Cotter
- Source: Electronics Letters, Volume 18, Issue 12, p. 495 –496
- DOI: 10.1049/el:19820336
- Type: Article
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–496
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Stimulated Brillouin scattering (SBS) in low-loss single-mode silica fibre is observed at 1.32 μm using a continuous-wave single-frequency Nd:YAG laser. The threshold for SBS is 5 mW and the transmitted power reaches a saturated maximum for launch powers exceeding about 10 mW. A conversion efficiency of 65% is observed. The Stokes frequency shift is 12.7±0.2 GHz.
Remarks on system simplification under consideration of time responses
- Author(s): N. Ashoor and V. Singh
- Source: Electronics Letters, Volume 18, Issue 12, p. 496 –497
- DOI: 10.1049/el:19820337
- Type: Article
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The letter highlights the significance of matching the terms of expansions around several points including s=0 and s=∞ in realising improved overall time-response approximation.
Low-threshold oxide stripe GaAs/GaAlAs lasers grown by MOCVD
- Author(s): C.S. Hong ; D. Kasemset ; N.B. Patel ; M.E. Kim ; P.D. Dapkus
- Source: Electronics Letters, Volume 18, Issue 12, p. 497 –499
- DOI: 10.1049/el:19820338
- Type: Article
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–499
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MOCVD-grown insulator defined stripe GaAs/GaAlAs lasers with stripe widths of 6, 10, 20 and 150 μm have been characterised. Uniform CW threshold currents as low as 45 mA, differential quantum efficiencies as high as 74%, and kink-free power levels as high as 20 mW/facet have been obtained in 160 μm long, 6 μm stripe lasers. The internal differential quantum efficiency measured from our 6 μm stripe lasers approaches one. Single longitudinal mode operation of these lasers has also been observed.
New optical fibre fabrication method
- Author(s): K. Susa ; I. Matsuyama ; S. Satoh ; T. Suganuma
- Source: Electronics Letters, Volume 18, Issue 12, p. 499 –500
- DOI: 10.1049/el:19820339
- Type: Article
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A new method for optical fibre fabrication has been found. The method is based on the so-called ‘sol-gel process’, which enables one to produce a core rod for optical fibre. Pure silica core fibre fabricated using this method exhibits an optical attenuation characteristic as low as 6 dB/km at a wavelength of 0.85 μm.
Two fast algorithms to compute the discrete receding horizon control gains
- Author(s): E. Yaz
- Source: Electronics Letters, Volume 18, Issue 12, p. 500 –501
- DOI: 10.1049/el:19820340
- Type: Article
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Two fast algorithms are proposed to calculate the feedback gains of the receding horizon method to suboptimally control linear time-invariant multi-input, multi-output discrete systems.
Output power saturation of BH laser under high current operation
- Author(s): Y. Nakano ; K. Takahei ; Y. Noguchi ; Y. Suzuki ; H. Nagai
- Source: Electronics Letters, Volume 18, Issue 12, p. 501 –502
- DOI: 10.1049/el:19820341
- Type: Article
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–502
(2)
Output power saturation of BH lasers under high current operation is analysed and it is concluded that such saturation is due to increase of leakage current through the burying layers. The mechanism of such leakage can be explained by a turn-on model of the bipolar transistor around the active region.
z-plane analysis of networks of distributed and discrete systems
- Author(s): W.D. Humpage and K.P. Wong
- Source: Electronics Letters, Volume 18, Issue 12, p. 502 –504
- DOI: 10.1049/el:19820342
- Type: Article
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502
–504
(3)
A general electromagnetic transient analysis method is given for networks of distributed and discrete systems in any combination and interconnection. The principal properties of the method derive primarily from an initial equation-system formulation in the z-plane.
Transient stimulated Brillouin scattering in long single-mode fibres
- Author(s): D. Cotter
- Source: Electronics Letters, Volume 18, Issue 12, p. 504 –506
- DOI: 10.1049/el:19820343
- Type: Article
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p.
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–506
(3)
Recent experiments show that stimulated Brillouin scattering (SBS) in low-loss fibres could place a severe limitation on optical power levels for coherent optical transmission. The letter analyses the transient stimulated scattering produced when the laser is modulated, and it is concluded that the limitations due to SBS could be circumvented by using particular modulation techniques.
Packet radio in a Rayleigh channel
- Author(s): F. Kuperus and J. Arnbak
- Source: Electronics Letters, Volume 18, Issue 12, p. 506 –507
- DOI: 10.1049/el:19820344
- Type: Article
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–507
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Statistical multiple access is analysed for a number of independent transmitter-receiver pairs exchanging data packets over a shared mobile-radio channel. Rayleigh fading ‘softens’ the channel, resulting in less packet contentions and higher traffic capacity than for the standard Aloha channel.
CW room-temperature visible single quantum well Ga0.73Al0.27As diode lasers grown by metalorganic chemical vapour deposition
- Author(s): R.D. Burnham ; D.R. Scifres ; W. Streifer
- Source: Electronics Letters, Volume 18, Issue 12, p. 507 –509
- DOI: 10.1049/el:19820345
- Type: Article
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–509
(3)
Room-temperature CW laser operation at 7125 Å has been achieved in a (Ga1−xAlxAs, x̃0.27) single quantum well double heterostructure (SQW-DH) diode laser. The laser consists of a 9 μm-wide delineated shallow proton stripe. The pulsed threshold current for a 250 μm long device is 115 mA whereas the CW threshold current is 140 mA. The CW external differential quantum efficiency is 60%.
Dielectric-waveguide filters using parallel-coupled grating resonators
- Author(s): G.L. Matthaei ; C.E. Harris ; D.C. Park ; Y. Kim
- Source: Electronics Letters, Volume 18, Issue 12, p. 509 –510
- DOI: 10.1049/el:19820346
- Type: Article
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p.
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–510
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Results for a new class of dielectric-waveguide bandpass filters are presented. The filters use pairs of gratings on a guide to make a resonator, and the resonators are coupled by side-by-side placement. Attenuation is by reflection around the passband and by absorption elsewhere.
Speed power in planar two-dimensional electron gas FET DCFL circuit: a theoretical approach
- Author(s): D. Delagebeaudeuf and Nuyen T. Linh
- Source: Electronics Letters, Volume 18, Issue 12, p. 510 –512
- DOI: 10.1049/el:19820347
- Type: Article
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–512
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A comparative study is made on the speed power of the two-dimensional electron gas FET (TEGFET) and the conventional GaAs FET. It is shown that the TEGFET is three times faster than the GaAs FET. Propagation delay times of 10 and 6 ps are predicted at 300 and 77 K, respectively, for a gate length of about 1 μm. Effects of electron velocity and mobility are given.
ZAP! Introducing the Zero-bias Avalanche Photodiode
- Author(s): T.P. Pearsall
- Source: Electronics Letters, Volume 18, Issue 12, p. 512 –514
- DOI: 10.1049/el:19820348
- Type: Article
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512
–514
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A novel heterostructure p-n junction diode is described which provides a photocurrent gain of 2 under zero external bias conditions. The necessary energy required to produce the additional electron-hole pair would be supplied by the internal electric field associated with the heterojunction energy gap difference. The ZAP diode structure has energy conversion applications as a photovoltaic detector whose efficiency may be enhanced by as much as 25% over that obtainable using homojunction solar cells. The device has, however, yet to be built.
Special cases of Fliege's complementary transformation for active RC networks
- Author(s): J.K. Stevenson and D.G. Haigh
- Source: Electronics Letters, Volume 18, Issue 12, p. 514 –515
- DOI: 10.1049/el:19820349
- Type: Article
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A transformation is given which consists of the application of Fliege's complementary transformation in a special way to a network of restricted topology. Since the transformation is a special case of Fliege's transformation, it does not alter the denominator of the network's voltage transfer ratio. However, whereas in Fliege's general transformation the numerator has to be determined by circuit analysis, in the new transformation the numerator is given directly. The application of Hilberman's transformation to the transformed network leads to an alternative transformation with similar properties.
Relationship between path length and attenuation of radio waves transmitted in a uniform rain-filled medium
- Author(s): S.A.J. Upton ; B.G. Evans ; A.R. Holt
- Source: Electronics Letters, Volume 18, Issue 12, p. 515 –517
- DOI: 10.1049/el:19820350
- Type: Article
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It has been accepted that rain attenuation (in an environment in which the rainfall rate is assumed uniform along the whole length of the radio link) is linear with respect to path length. It is shown here that for nonspherical raindrops this is not generally the case. Results over the frequency band 3–30 GHz are presented. These demonstrate that, in certain circumstances, use of the path-length-related model for linear and circular polarisations can lead to significant errors.
High-speed low-power DCFL using planar two-dimensional electron gas FET technology
- Author(s): Pham N. Tung ; P. Delescluse ; D. Delagebeaudeuf ; M. Laviron ; J. Chaplart ; Nuyen T. Linh
- Source: Electronics Letters, Volume 18, Issue 12, p. 517 –519
- DOI: 10.1049/el:19820351
- Type: Article
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517
–519
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Planar two-dimensional electron gas FETs (TEGFETs) have been shown to have ultra-high speed and low power in DCFL circuits operating at room temperature: 18.4 ps at 900 μW and 32.5 ps at 62 μW. The latter result and the simplicity of the process involved are compatible with VLSI requirements.
Global convergence of Newton's method in the DC analysis of single-transistor networks
- Author(s): C.P. Reames and A.N. Willson
- Source: Electronics Letters, Volume 18, Issue 12, p. 519 –520
- DOI: 10.1049/el:19820352
- Type: Article
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Global convergence of Newton's method is proved for the DC equations of a one-transistor network. Sufficient conditions are also given for global convergence in networks of n transistors.
Mutual coupling between microstrip patch antennas
- Author(s): M. Malkomes
- Source: Electronics Letters, Volume 18, Issue 12, p. 520 –522
- DOI: 10.1049/el:19820353
- Type: Article
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A theoretical approach to the mutual coupling phenomenon between microstrip patch antennas of arbitrary geometry and alignment is presented. The theory employs an equivalent magnetic wall model for each single radiator, a series expansion in resonant modes in connection with a reaction concept treatment of antenna interaction. Good agreement of theoretical and experimental data is observed in a wide frequency range for various element spacings.
Intermittent fault coverage during test of electronic components and systems
- Author(s): J. Bicknell
- Source: Electronics Letters, Volume 18, Issue 12, p. 522 –523
- DOI: 10.1049/el:19820354
- Type: Article
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–523
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Fault-detection experiments for electronic components and systems are usually designed for the detection of permanent or data-dependent faults. Treatment of intermittent faults in the literature has been restricted to the use of Markov models for the design of fault experiments capable of detecting intermittent faults having specified transition probabilities. In the letter a transformation has been introduced allowing an estimation of the fault coverage of a particular test strategy to be made without assumptions about the characteristics of likely faults.
Experimental assessment of a 140 Mbit/s coherent optical receiver at 1.52 μm
- Author(s): T.G. Hodgkinson ; R. Wyatt ; D.W. Smith
- Source: Electronics Letters, Volume 18, Issue 12, p. 523 –525
- DOI: 10.1049/el:19820355
- Type: Article
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Homodyne detection has given a 10 dB improvement in receiver sensitivity over direct detection at a wavelength of 1.52 μm and a data rate of 140 Mbit/s. This result was achieved with a local oscillator power of only −32 dBm.
Resistive multiport scattering matrix realisation using operational amplifiers
- Author(s): J. Pospíšil
- Source: Electronics Letters, Volume 18, Issue 12, p. 525 –527
- DOI: 10.1049/el:19820356
- Type: Article
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A new structure realising the voltage-scattering matrix of resistive n-port networks using resistors and operational amplifiers is proposed. The effect of a finite gain-bandwidth product of operational amplifiers is discussed.
Pressure dependence of threshold current in GaxIn1−xAsyP1−y lasers
- Author(s): D. Patel ; A.R. Adams ; P.D. Greene ; G.D. Henshall
- Source: Electronics Letters, Volume 18, Issue 12, p. 527 –528
- DOI: 10.1049/el:19820357
- Type: Article
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The threshold current in 20 μm stripe GaxIn1−xAsyP1−y lasers operating at 1.3 μm wavelength decreases with increasing pressure, whereas the opposite effect occurs in lasers made of Ga1−xAlxAs The magnitude of the change observed in quaternary lasers is consistent with the presence of intervalence band absorption or Auger recombination, but not with the other mechanisms considered.
State-sequenced polarity crosscorrelator
- Author(s): M.A. Browne ; R.J. Deloughry ; R.G. Green ; R. Thorn
- Source: Electronics Letters, Volume 18, Issue 12, p. 528 –530
- DOI: 10.1049/el:19820358
- Type: Article
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A state-sequenced polarity crosscorrelator is described which is controlled by a flexible ROM sequencing unit and uses overflow peak detection. Delay resolution from <38 μs down to any desired value can be accommodated. Calibration using a CCD delay line indicates delay time measurements with an accuracy of better than 2% of the reading.
Finite-element analysis of flat overlay waveguides for acoustic surface waves using acoustic surface impedance
- Author(s): M. Koshiba ; K. Hayata ; M. Suzuki
- Source: Electronics Letters, Volume 18, Issue 12, p. 530 –531
- DOI: 10.1049/el:19820359
- Type: Article
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An efficient finite-element program utilising acoustic surface impedance is described for the analysis of flat overlay wave-guides for acoustic surface waves. The results obtained agree well with the earlier theoretical and experimental results.
Parasitic-compensated second-order switched-capacitor filters
- Author(s): P.V. Ananda Mohan ; V. Ramachandran ; M.N.S. Swamy
- Source: Electronics Letters, Volume 18, Issue 12, p. 531 –533
- DOI: 10.1049/el:19820360
- Type: Article
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A method, for compensating the effect of top-plate parasitic capacitances (otherwise unavoidable) in certain recently described second-order lowpass, highpass and bandpass switched-capacitor filters, is described.
Be-implanted p-n junctions in Ga0.47In0.53As
- Author(s): L. Vescan ; J. Selders ; H. Kräutle ; W. Kütt ; H. Beneking
- Source: Electronics Letters, Volume 18, Issue 12, p. 533 –534
- DOI: 10.1049/el:19820361
- Type: Article
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The fabrication of Be-implanated Ga0.47In0.53As p-n diodes is described. After annealing the diodes exhibit saturation current densities of 1.5×10−4 A/cm−2 and an ideality factor of 1.6. The built-in voltage of ̃0.7 V demonstrates the feasibility of their application to electronic devices. SIMS and C/V measurements are consistent with theoretical data.
Planar self-aligned ion-implanted InP MOSFET
- Author(s): D.C. Cameron ; L.D. Irving ; C.R. Whitehouse ; J. Woodward
- Source: Electronics Letters, Volume 18, Issue 12, p. 534 –536
- DOI: 10.1049/el:19820362
- Type: Article
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n-channel enhancement-mode InP MOSFETs have been fabricated on Fe-doped semi-insulating material using a planar self-aligned Mo gate process with ion-implanted source and drain contact regions. These devices showed high mobilities up to 2400 cm2/Vs and excellent uniformity and stability.
Dispersion characteristics of slot lines on a ferrite substrate by a mode-matching technique
- Author(s): G. Böck
- Source: Electronics Letters, Volume 18, Issue 12, p. 536 –537
- DOI: 10.1049/el:19820363
- Type: Article
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A mode-matching technique for analysis of slot lines on a ferrite substrate with a finite or infinite thin metal coating is investigated. The method is exact apart from numerical evaluation, where the infinite series have to be approximated. It is shown that accurate numerical results can be obtained with even a 4×4 matrix.
C-2C ladder voltage dividers for application in all-MOS A/D convertors
- Author(s): S.P. Singh ; A. Prabhakar ; A.B. Bhattacharyya
- Source: Electronics Letters, Volume 18, Issue 12, page: 537 –537
- DOI: 10.1049/el:19820364
- Type: Article
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C-2C ladders for A/D conversion (analogous to the conventional R-2R ladders) are reported which use only 22 elementary capacitors for 8-bit conversion and 34 elementary capacitors for 10-bit conversion. The nonlinearity contributed by the parasitic capacitances is within ±0.15 LSB.
Analysis of conductor-backed coplanar waveguide
- Author(s): Y.C. Shih and T. Itoh
- Source: Electronics Letters, Volume 18, Issue 12, p. 538 –440
- DOI: 10.1049/el:19820365
- Type: Article
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The transmission properties of a coplanar waveguide printed on conductor-backed substrates are analysed using the spectral-domain technique. For a fixed substrate thickness, the characteristic impedance and the phase constant may be varied independently by simply adjusting the widths of the centre strip and the slots in the transmission line.
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