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image of Volume 23, Issue 25
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 23, Issue 25, 3 December 1987

Volumes & issues:

Volume 23, Issue 25

3 December 1987

Optically excited resonant beam pressure sensor
Very low threshold current densities (under 100 A/cm2) in AlGaAs/GaAs single-quantum-well GRINSCH lasers grown by molecular beam epitaxy
  • Author(s): H.Z. Chen ; A. Ghaffari ; H. Morkoc ; A. Yariv
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1334 –1335
  • DOI:  10.1049/el:19870922
  • Type: Article
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  • p. 1334 –1335 (2)
    Threshold current densities as low as 80 A/cm2 for 3.3 mm-long cavity lasers, and 93 A/cm2 for 520 μm-long cavity lasers have been obtained in AlGaAs/GaAs graded-index separate-confinement heterostructure (GRINSCH) single-quantum-well lasers with quantum-well widths between 65–165 A grown by molecular beam epitaxy. The structures were prepared on (100) GaAs substrates and do not display the earlier reported dependence of lasing threshold characteristics on the quantum-well thickness in the range studied (65–165 A).
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Correlation-immunity of Boolean functions
New postdetection processing technique for frame synchronisers
  • Author(s): L.-K. Shark ; R.J. Simpson ; T.J. Terrell
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1337 –1338
  • DOI:  10.1049/el:19870924
  • Type: Article
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  • p. 1337 –1338 (2)
    A new postdetection processing technique to achieve lock-mode frame synchronisation is described. The method is based on a combination of the minimum-error principle and the conventional window technique. Compared with the performance of existing frame synchronisers the new technique is shown to produce an increased unique-word detection probability and a reduced false alarm probability.
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Novel high-speed LED transmitter for single-mode fibre and wideband loop transmission systems
Constrained l2 suboptimal model reduction
AlGaAs/GaAs visible distributed feedback laser operating at 770 nm
  • Author(s): Y. Nakano ; Y. Luo ; K. Tada
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1342 –1343
  • DOI:  10.1049/el:19870927
  • Type: Article
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  • p. 1342 –1343 (2)
    A visible-light AlGaAs/GaAs DFB laser with practical characteristics oscillating at 770 nm has been fabricated by using two-step liquid phase epitaxy for the first time. Threshold current of 90 mA measured at room temperature is satisfactorily low for its simple oxide stripe structure. The same DFB mode oscillation without mode hopping has been maintained in a considerably wide range of temperature. The results show a possibility of realising a high-performance DFB laser in the visible-wavaelength region.
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Highly efficient linearly polarised Raman generation in a germania-core optical fibre
Outage probability calculations for a mobile radio system having two log-normal interferers
Langmuir-Blodgett deposited cadmium gate inverted InP-GaInAs modulation-doped field-effect transistors
  • Author(s): W.K. Chan ; H.M. Cox ; J.H. Abeles ; S.P. Kelty
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1346 –1348
  • DOI:  10.1049/el:19870930
  • Type: Article
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  • p. 1346 –1348 (3)
    We report on the Langmuir-Blodgett film deposition and plasma etching of cadmium distearate on n-Gao.47Ino.53As to form a high-barrier-height Schottky barrier. Using this technique to form the gate electrode, we fabricated a 1μm-gate-length inverted InP-GalnAs modulation-doped field-effect transistor (MODFET) with an extrinsic transconductance of 170mS/mm and a cutoff frequencyfT of 19 GHz.
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Thermometry of impedances by correlation radiometry
  • Author(s): P. Lauer ; Y. Leroy ; J.C. van de Velde ; A. Mamouni
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1348 –1350
  • DOI:  10.1049/el:19870931
  • Type: Article
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  • p. 1348 –1350 (3)
    Theoretical considerations and experiments indicate how the temperature of an impedance Z(f) and its position on the line connected to the two inputs of a correlation radiometer can be deduced from the radiometric signals. Such a process should be considered for thermometric applications based on the analysis of the radiometric signal produced by a nonisothermal lossy line.
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GMSK frequency detection using decision feedback equalisation
  • Author(s): K. Ohno  and  F. Adachi
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1350 –1352
  • DOI:  10.1049/el:19870932
  • Type: Article
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  • p. 1350 –1352 (3)
    Frequency detection of GMSK signals using one-bit decision feedback equalisation (DFE) in conjunction with offset decision instant is presented. Experiments on a 16kbit/GMSK signal reception with a premodulation filter bandwidth-bit duration product (Bb T) of 0-25 (typical for mobile radio applications) show that, compared to MSK signal reception, a bit error rate (BER) of 10-2 is obtained with a loss of about 4dB in the signal energy per bit/noise power density ratio (Eb/N0) in the additive white Gaussian noise (AWGN) channels. In the cochannel interference limited channels, a BER of 10-2 is obtainable at a signal/interference power ratio (SIR) about 5-5 dB larger than in the case of MSK signal reception.
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1 Gbit/s automatic-power-control-free zero-bias modulation of very-low threshold MQW laser diodes
  • Author(s): M. Nakamura ; H. Furuyama ; A. Kurobe
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1352 –1353
  • DOI:  10.1049/el:19870933
  • Type: Article
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  • p. 1352 –1353 (2)
    The first 1 Gbit/s, automatic-power-control-free zero-bias modulation has been successfully demonstrated using very low-threshold GaAs/AlGaAs MQW lasers. A stable multi-longitudinal mode oscillation due to zero-bias modulation was also observed. This result simplifies driving circuitry and is an important step towards realisation of high-speed and high-density optoelectronic integrated circuits.
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Influence of raypath parameters on digital radio outage
Equivalent circuit modelling and derivative characterisation of 1.3μm injection lasers
  • Author(s): D.E. Ackley
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1354 –1356
  • DOI:  10.1049/el:19870935
  • Type: Article
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  • p. 1354 –1356 (3)
    An equivalent circuit model has been developed to describe the CW output characteristics of 1.3 μm injection lasers. Using the model, full derivative characteristics can be generated to emulate the operation of the devices. The model has been specifically applied to optimise the operation of 1.3μm DCPBH lasers by identifying the dominant leakage paths and suggesting structural improvements which minimise the leakage contribution.
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Hot electron degradation in the source of asymmetrical LDD structures
Depolarisation in Ti:LiNbO3 waveguides and its effect on circuit design
Performance of an 8×8 LiNbO3switch matrix as a gigahertz self-routing switching node
  • Author(s): D.J. Blumenthal ; P.R. Prucnal ; L. Thylen ; P. Granestrand
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1359 –1360
  • DOI:  10.1049/el:19870938
  • Type: Article
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  • p. 1359 –1360 (2)
    The performance of an LiNbO3 integrated-optic crossbar switch as a node in a gigahertz self-routing network is measured. Switch throughput supports 12.5 Gbit/s signals with a measured switching speed of 1.33 GHz. Crosstalk due to RF/ acousto-optic coupling and modulation depth are reported at 1.33 GHz. Optical self-routing of l00 Mbit/s information using the 8×8 switch is demonstrated.
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Multichannel intermodulation distortion in high-speed GaInAsP lasers
  • Author(s): P. Iannone  and  T.E. Darcie
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1361 –1362
  • DOI:  10.1049/el:19870939
  • Type: Article
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  • p. 1361 –1362 (2)
    We present an experimental study of intermodulation distortion (IMD) in high-speed, long-wavelength GaInAsP lasers modulated up to 8 GHz. It is found that three-tone distortion products are the dominant contribution to IMD interference when the number of subcarriers is large. These distortion data are used with a simple theory to predict accurately the measured signal/noise ratio for each channel of a multichannel subcarrier system.
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Threshold selection algorithm for extracting a uniform colour region in an image
  • Author(s): Byung-Hwa Chang ; Seong-Dae Kim ; Jae-Kyoon Kim
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1362 –1363
  • DOI:  10.1049/el:19870940
  • Type: Article
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  • p. 1362 –1363 (2)
    A new threshold selection algorithm for multidimensional feature space is proposed, and its applications to colour images are shown. This algorithm is based on tho recursive application of a simple 1-D threshold selection method (valley detection) to the conditional 1-D histograms. Although the performance of the algorithm such as convergence rate etc. is not yet evaluated, uniform colour regions are successfully extracted by the proposed algorithm for several colour images.
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MOVPE studies for the development of GaInAsP/InP lasers with semi-insulating InP blocking layers
Preservation of polarisation orthogonality through a linear optical system
  • Author(s): L.J. Cimini ; I.M.I. Habbab ; R.K. John ; A.A.M. Saleh
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1365 –1366
  • DOI:  10.1049/el:19870942
  • Type: Article
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  • p. 1365 –1366 (2)
    It is well known that when two orthogonally polarised optical waves are launched into an optical medium they may experience a loss in orthogonality. In the letter we derive a simple bound on this loss. Our result predicts that orthogonality is virtually preserved for many common single-mode optical components (for example, long lengths of fibres, directional couplers and filters).
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Effect of the non-Lorentzian lineshape of semiconductor laser on a PSK coherent heterodyne optical receiver
Gunn diode oscillator constructed in nonradiative dielectric waveguide
Polarisation-diversity receiver for coherent FSK communications
  • Author(s): T.E. Darcie ; B. Glance ; K. Gayliard ; J.R. Talman ; B.L. Kasper ; C.A. Burrus
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1369 –1371
  • DOI:  10.1049/el:19870945
  • Type: Article
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  • p. 1369 –1371 (3)
    A polarisation-insensitive optical heterodyne receiver, in which two signals with orthogonal polarisations are independently detected and demodulated, and subsequently combined, has been demonstrated for FSK-modulated signals at 50 Mbit/s with a sensitivity of −55.5 dBm (Pe=10−9). The receiver uses the entire received signal and local oscillator signal with only one photodiode in each branch. Differences between the two PINFET detectors result in a ±ldBm sensitivity variation for all polarisation states of the received signal.
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Formulas for direct frequency modulation response of two-electrode diode lasers: proposals for improvement
Elimination of errors in absolute position encoders using m-sequences
  • Author(s): G.H. Tomlinson
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1372 –1374
  • DOI:  10.1049/el:19870947
  • Type: Article
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  • p. 1372 –1374 (3)
    The position of a linear or shaft-angle encoder can be obtained by reading r consecutive bits of an m-sequence of length L = 2r — 1, written on a single track. The errors that occur when a read is attempted during a transition between bits are considered. It is shown how the errors can be eliminated by means of additional heads. It is found that the number of extra heads required depends on the characteristic polynomial f(x) of the m-sequence and it is shown that, by correct choice of f(x), only two extra heads are required.
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Accurate prediction of radiation patterns of dielectric resonator antennas
Relationship between linewidth and chirp reductions in gain-detuned composite-cavity semiconductor lasers
Accuracy of standard patch antenna models
  • Author(s): T.M. Willis  and  D.L. Sengupta
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1376 –1378
  • DOI:  10.1049/el:19870950
  • Type: Article
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  • p. 1376 –1378 (3)
    The validity of the leaky cavity and transmission-line models to predict the far zone fields from a microstrip patch antenna is investigated. The prediction of this radiation requires a knowledge of the total current on the antenna. Since the approximate techniques utilise only the current on the bottom surface of the antenna, the relative importance of top and bottom surface currents are examined.
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Phase-matched mode convertor in LiNbO3 using near-Z-axis propagation
Design of crystal oscillators with fundamental frequencies in the uhf and microwave regions
Considerations on group delay fitting equations for dispersion-shifted fibres
  • Author(s): Y. Miyajima ; T. Kawata ; Y. Negishi
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1381 –1382
  • DOI:  10.1049/el:19870953
  • Type: Article
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  • p. 1381 –1382 (2)
    Chromatic dispersion measurement accuracy was examined experimentally for four kinds of group delay fitting equation which have been proposed to date. It was found that the five-term Sellmeier equation is appropriate for dispersion-shifted fibres with various refractive index profiles. Also, it was demonstrated that the maximum difference in zero-dispersion wavelength among the four equations is less than 0.67nm by selecting six measuring wavelengths between 1.49μm and 1.59μm using the LD phase-shift method.
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Polarisation-insensitive operation of coherent FSK transmission system using polarisation diversity
High-frequency acousto-optic deflector using ZnO thin films deposited on an amorphous substrate
Wavelength dependence of a D-fibre optical switch
Optical amplifier configurations with low polarisation sensitivity
Objective measurement of receiver sensitivity
  • Author(s): B.A. Wyndham  and  T.B. Nichols
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1388 –1389
  • DOI:  10.1049/el:19870958
  • Type: Article
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  • p. 1388 –1389 (2)
    The sensitivity of radar receivers is checked with a pulsed radio frequency signal which is adjusted until the observed magnitude is distinguishable from the background noise level as displayed on an oscilloscope. Because of the noisy nature of the display the results are highly subjective, but by eliminating the idiosyncratic element, a calibration instrument has been designed to give a rapid and accurate presentation to the operator.
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New channel routing algorithm for bit-slice applications
Comparison of phase modulation of GaAs/AlGaAs double heterostructures
  • Author(s): J. Faist ; F.K. Reinhart ; D. Martin
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1391 –1392
  • DOI:  10.1049/el:19870960
  • Type: Article
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  • p. 1391 –1392 (2)
    The performance of double-heterostructure GaAs/AlxGa1−xs phase modulators with different doping profiles are systematically compared. The largest phase modulation of l.75rad/V mm at a wavelength of 1.09μm was obtained with an active layer doped at n=3 × 1017cm−3. However, an intrinsic active layer gives the lowest characteristic modulation energy needed for high-frequency modulation.
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Intermodulation distortion in optical amplifiers from carrier-density modulation
  • Author(s): T.E. Darcie ; R.M. Jopson ; R.W. Tkach
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1392 –1394
  • DOI:  10.1049/el:19870961
  • Type: Article
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  • p. 1392 –1394 (3)
    We present a theoretical model describing the generation of intermodulation products (IMPs) in semiconductor optical amplifiers by signal-induced carrier-density modulation. The IMPs depend strongly on the linewidth-enhancement factor and the ratio of output intensity to the saturation intensity of the amplifier. Calculation of the total intermodulation penalty for multichannel amplifier applications is possible using the expressions presented.
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Measurement of carrier-density mediated intermodulation distortion in an optical amplifier
  • Author(s): R.M. Jopson ; T.E. Darcie ; K.T. Gayliard ; R.T. Ku ; R.E. Tench ; T.C. Rice ; N.A. Olsson
  • Source: Electronics Letters, Volume 23, Issue 25, p. 1394 –1395
  • DOI:  10.1049/el:19870962
  • Type: Article
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  • p. 1394 –1395 (2)
    We measured intermodulation distortion (IMD) generated by the presence of two optical tones separated by up to 1 GHz in a 1.3μm near-travelling-wave optical amplifier. The measured distortion agrees with calculations of third-order nonlinearity caused by carrier-density modulation. The third-order intercept of 5dBm may be more restrictive in closely spaced frequency-multiplexed systems than gain saturation.
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High-power operation of long-cavity phase-locked laser arrays
Erratum: New analysis of LED to single-mode fibre coupling
Erratum: Finite-element solution of arbitrarily nonlinear, graded-index slab waveguides
Erratum: Open-cavity resonator as high-Q microstrip circuit element
Erratum: Analysis of a narrow slit in a parallel-plate transmission line: E-polarisation case
Erratum: Block-diagonal structure of Walsh-Hadamard/discrete cosine transform
Erratum: Differential phase error in pulse-width-modulated TV transmission systems
Erratum: CMOS circuits made in thin SIMOX films
Erratum: Resistance of Ti:LiNbO3 devices to ionising radiation

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