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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 27, Issue 6, 14 March 1991

Volumes & issues:

Volume 27, Issue 6

14 March 1991

Statistical modelling of polarisation induced fading in interferometric fibre sensors
Scattering losses in single and double heterostructure semiconductor optical rib waveguides
Epitaxial liftoff of AlAs/GaAs double barrier resonant tunnelling diodes
  • Author(s): A.J. Tsao ; V.K. Reddy ; D.P. Neikirk
  • Source: Electronics Letters, Volume 27, Issue 6, p. 484 –486
  • DOI:  10.1049/el:19910305
  • Type: Article
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  • p. 484 –486 (3)
    For the first time, the successful removal of AlAs/GaAs double barrier resonant tunnelling diodes from the substrate using the epitaxial liftoff technique is reported. Ohmic contacts were formed to the top and bottom of the devices, using indium-alloyed ohmic contacts for the backside of the lifted-off diodes. Room temperature peak-to-valley ratios of 3.4 with peak current densities of 50 kA/cm2 were obtained.
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Extended spectral domain approach for analysis of lossy cylindrical dielectric resonators
  • Author(s): Ao Sheng Rong  and  Cao Yang
  • Source: Electronics Letters, Volume 27, Issue 6, p. 486 –488
  • DOI:  10.1049/el:19910306
  • Type: Article
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  • p. 486 –488 (3)
    The spectral domain approach is extended for evaluating both the resonant frequency and Q factor of a lossy cylindrical dielectric resonator operating in TE0 modes, taking into account the effects of conducting enclosure and supporting substrate. On the basis of the equivalence principle, the circular electric currents are introduced to simulate the fields inside and outside the cylindrical dielectric sample, which separates the original problems into two auxiliary structures with radially homogeneous multilayered dielectrics. Using the spectral immittance method in conjunction with the point-matching method, the characteristic equations are derived. The present technique has no need to determine the time-consuming, complex higher-order modes. Some typical examples are computed. The numerical results agree well with experimental data available in the literature.
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Q and V band power InGaAs MESFETs
  • Author(s): G.W. Wang  and  Y. Chang
  • Source: Electronics Letters, Volume 27, Issue 6, p. 488 –489
  • DOI:  10.1049/el:19910307
  • Type: Article
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  • p. 488 –489 (2)
    Excellent power performance at 44 and 60 GHz demonstrated by 0.25 μm gate InGaAs MESFETs is reported. From small-signal S-parameter measurements, these devices typically have extrinsic ft greater than 100 GHz. At 1 dB compression point, a 150 μm wide MESFET shows a power added efficiency of 33% with an output power of 60.8 mW (0.43 W/mm) at 44 GHz. For 200 μm wide devices, the power added efficiency was measured to be 19% with an output power of 82 mW (0.41 W/mm) at 60 GHz. These results indicate that InGaAs MESFETs are viable millimetre-wave power devices.
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State variable sinusoidal switched-current oscillator
Antenna-coupled microwave phase shifters using GaAs varactors
High power, diffraction-limited emission from monolithically integrated active grating master oscillator power amplifier
  • Author(s): D. Mehuys ; D.F. Welch ; R. Parke ; R.G. Waarts ; A. Hardy ; D. Scifres
  • Source: Electronics Letters, Volume 27, Issue 6, p. 492 –494
  • DOI:  10.1049/el:19910310
  • Type: Article
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  • p. 492 –494 (3)
    A novel monolithically integrated master oscillator power amplifier with a distributed amplifier/grating output coupler is demonstrated which emits 370 mW in a single-frequency diffraction-limited beam without any form of active phase control. The distributed amplifier/grating output coupler results in a guided mode power that saturates along the direction of propagation, providing a uniform carrier density to preserve the flatness of the radiated phase front.
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Function dependent fully testable programmable logic array
Permittivity and permeability of chiralic mixture: application of logarithmic law of mixing
  • Author(s): P.S. Neelakanta ; K. Subramaniam ; Gu Chaoli
  • Source: Electronics Letters, Volume 27, Issue 6, p. 496 –497
  • DOI:  10.1049/el:19910312
  • Type: Article
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  • p. 496 –497 (2)
    The Lichtenecker–Rother logarithmic law of mixing is extended to determine the permittivity and permeability of two-phase chiral media. Relevant formulations express the effective permittivity, permeability and chirality of a two-component mixture formed by chiralic inclusions dispersed in an achiralic host medium, in closed forms. Computed results are compared with existing formulation(s) based on Maxwell–Garnett theory.
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Integrated optical inverter using light amplifying optical switch (LAOS)
Flip-chip solder bond mounting of laser diodes
Al0.25Ga0.75As/In0.25Ga0.75As pseudomorphic MODFET with high DC and RF performance
  • Author(s): J. Dickmann ; A. Geyer ; H. Daembkes ; H. Nickel ; R. Lösch ; W. Schlapp
  • Source: Electronics Letters, Volume 27, Issue 6, p. 501 –502
  • DOI:  10.1049/el:19910315
  • Type: Article
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  • p. 501 –502 (2)
    AlGaAs/InGaAs MODFETs having 25% indium in the channel and LG = 0.35 μm have been fabricated. From DC device characterisation, a maximum saturation current of 670 mA/mm and an extrinsic transconductance of 500 mS/mm have been measured. A maximum unilateral gain cutoff frequency of fc = 205 GHz and a maximum current gain cutoff frequency of fT = 86 GHz have been achieved. Bias dependence of fc and fT has been measured. At 12 GHz a minimum noise figure of NF = 0.8 dB and an associated gain of 11 dB have been measured.
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24 Gbit/s regenerating demultiplexer IC in silicon bipolar technology
Current multiplier/divider circuit
Design and performance of 20 dB gain two-tier matrix distributed amplifier
  • Author(s): S. D'agostino ; G. D'inzeo ; G. Grifoni ; P. Marietti ; G. Panariello
  • Source: Electronics Letters, Volume 27, Issue 6, p. 506 –507
  • DOI:  10.1049/el:19910318
  • Type: Article
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  • p. 506 –507 (2)
    A matrix distributed amplifier, having a gain of 20 dB with a noise figure of 5 dB in the frequency range between 0.5–12 GHz, is presented. The amplifier, realised in hybrid technology using commercially available GaAs HEMTs, incorporates a novel scheme which allows the biasing of a single stage of the two tier amplifier (two rows of active devices) with a unique controlling resistance and, at the same time, the cascading of the two FETs of each stage. The computed results obtained using a small signal model for each FET fit rather well with the measurements in the whole frequency range.
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New method for extraction of effective channel length in submicron MOSFETs
Cellular telemetry by microwaves
35 dB optical gain at 2.716 μm in erbium doped ZBLAN fibre pumped at 0.642 μm
  • Author(s): D. Ronarch ; M. Guibert ; F. Auzel ; D. Mechenin ; J.Y. Allain ; H. Poignant
  • Source: Electronics Letters, Volume 27, Issue 6, p. 511 –513
  • DOI:  10.1049/el:19910321
  • Type: Article
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  • p. 511 –513 (3)
    An optical gain of 35 dB at 2.716 μm signal wavelength has been measured in an erbium doped ZBLAN fibre. A pump-wavelength scanning determined the pump wavelength for maximum gain. This pump wavelength was found to be 0.642 μm. The maximum absorption wavelength for this Er3+ doped fibre is 0.649 μm. It was deduced that the excited state absorption process improves the gain performance of such fibres at the signal wavelength considered.
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Gain compression and phase-amplitude coupling in GaInAs quantum well lasers with three, five and seven wells
  • Author(s): M. Cavelier ; J.-M. Lourtioz ; J.-M. Xie ; L. Chusseau ; B. de Cremoux ; M. Krawkowski ; D. Rondi
  • Source: Electronics Letters, Volume 27, Issue 6, p. 513 –515
  • DOI:  10.1049/el:19910322
  • Type: Article
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  • p. 513 –515 (3)
    The gain compression and phase-amplitude coupling factors are measured along with the differential gain in GaInAs/GaInAsP quantum well lasers with three, five and seven wells. Results are compared with those obtained for a conventional bulk laser of the same quaternary material. The ultimate modulation bandwidth deduced from the measurements is shown to increase with the number of wells. For the seven well laser, the ultimate modulation bandwidth is found to reasonably approach that obtained for the bulk laser while the phase-amplitude coupling factor is 2.6 times smaller.
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Novel free-space optical interconnection architecture employing array devices
Gallium arsenide solid state travelling wave amplifier at 8 GHz
Polarisation-insensitive fibre optic Michelson interferometer
32 channel WDM multiplexer with 1 nm channel spacing and 0.7 nm bandwidth
  • Author(s): D.R. Wisely
  • Source: Electronics Letters, Volume 27, Issue 6, p. 520 –521
  • DOI:  10.1049/el:19910326
  • Type: Article
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  • p. 520 –521 (2)
    A high density WDM multiplexer capable of combining 32 channels spaced 1 nm apart onto a monomode fibre is reported. The multiplexer incorporates a microlens array to give a channel bandwidth of 0.7 nm. The wavelength range of operation is 1.5285 μm to 1.5595 μm, within the erbium fibre amplification range. The mean insertion loss over the 32 channels is 6.7 dB and the polarisation sensitivity is less than 0.7 dB.
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Electronically tunable ring resonator microstrip and suspended-substrate filters
  • Author(s): S. Kumar
  • Source: Electronics Letters, Volume 27, Issue 6, p. 521 –523
  • DOI:  10.1049/el:19910327
  • Type: Article
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  • p. 521 –523 (3)
    Electronically tunable ring resonator microstrip and suspended substrate microwave filters with high tuning speed are presented. The filters are realised using two coupled ring resonators with GaAs varactors as the tuning elements. Computer optimised circuits are used at the input and the output to obtain better than 10 dB return loss across the tuning band. Tuning ranges of 1.075–2.25 GHz for the microstrip filter and 1.35–2.075 GHz for the narrower suspended substrate filter are predicted by the computer simulation.
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Simulation of the RF performance of AlGaAs/GaAs heterojunction bipolar transistors: application of fast Fourier transform
  • Author(s): L.L. Liou ; A. Ezis ; K. Ikossi-Anastasiou ; C.I. Huang
  • Source: Electronics Letters, Volume 27, Issue 6, p. 523 –524
  • DOI:  10.1049/el:19910328
  • Type: Article
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  • p. 523 –524 (2)
    The results of a Fourier decomposition technique approach to simulate the small signal microwave performance of AlGaAs/GaAs heterojunction bipolar transistors are reported. For demonstration, a 1-D numerical simulation code is used to obtain the transient base and collector currents resulting from a small base–emitter voltage step superimposed on a DC bias. The frequency-dependent common–emitter current gain and associated phase shift are then determined by using the discrete fast Fourier transform technique. This approach gives the same accuracy as obtained by the traditional point-by-point method with the benefit of acquiring a wide range of frequency response with just one input signal waveform.
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Comment: Novel algorithm for Clos-type networks
Reply: Novel algorithm for Clos-type networks
Selforthogonal convolutional codes derived from linear congruences
  • Author(s): V.C. Da Rocha
  • Source: Electronics Letters, Volume 27, Issue 6, p. 526 –528
  • DOI:  10.1049/el:19910331
  • Type: Article
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  • p. 526 –528 (3)
    A systematic procedure is presented for the construction of class, of binary (n, k, m) selforthogonal convolutional codes (SOCC) of minimum distance d = n−k+1 = J+1, where 1<J< p, k<p, m+1<p, and p is a prime number. An extension of the basic construction technique is provided for the case where a power of a prime, i.e. q = pe, is used instead of p. Unequal error protection SOCCs are obtained through a minor modification in the parity check matrix.
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Multibit oversampled Σ–Δ A/D convertor with nonuniform quantisation
New technique for low-angle radar tracking
Linewidth reduction in wavelength tunable laser diodes by voltage control
  • Author(s): M.-C. Amman ; S. Illek ; H. Lang
  • Source: Electronics Letters, Volume 27, Issue 6, p. 531 –532
  • DOI:  10.1049/el:19910334
  • Type: Article
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  • p. 531 –532 (2)
    The spectral linewidth of wavelength tunable laser diodes usually broadens during tuning due to injection recombination shot noise in the tuning regions. This broadening dominates the linewidth of large range continuously tunable laser diodes. An effective suppression of this broadening mechanism is obtained by control of the tuning region voltage instead of current. Impacts for the design of large range tunable narrow linewidth devices are discussed.
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Mutual coupling between electromagnetically coupled rectangular patch antennas
New coplanar waveguide/stripline feed network for seven patch hexagonal CP subarray
  • Author(s): R.N. Simons ; R.Q. Lee ; G.R. Lindamood
  • Source: Electronics Letters, Volume 27, Issue 6, p. 533 –535
  • DOI:  10.1049/el:19910336
  • Type: Article
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  • p. 533 –535 (3)
    A novel CPW-to-stripline post coupler is demonstrated. This device couples the output power from a coax-to-CPW inphase seven-way radial power divider to a balanced stripline line stretcher and together forms a multilayer probe-type feed network. The feed network excites a seven patch hexagonal circularly polarised (CP) subarray. The measured return loss and insertion loss of the coupler are better than 17 dB and 0.25 dB at the design frequency of 2.875 GHz. The measured on-axis axial ratio for the left hand circular polarisation (LHCP) is 1.5 dB and the 3 dB beam widths are 36° in the principal planes of the subarray. The gain of the subarray is 13 dB. The input return loss of the subarray is better than 10 dB.
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180 photons/bit in 140 Mbit/s, 305 km direct-detection optical transmission experiment
Acoustic microscopy investigations of nonplanar surfaces
  • Author(s): Z. Hadjoub ; A. Doghmane ; R. Caplain ; J.M. Saurel ; J. Attal
  • Source: Electronics Letters, Volume 27, Issue 6, p. 537 –539
  • DOI:  10.1049/el:19910338
  • Type: Article
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  • p. 537 –539 (3)
    It is well known that the acoustic microscope is used to characterise planar objects via the V(z) signature. Extending this technique to curved surfaces, it is demonstrated theoretically, and on stainless steel balls, that the spacing Δz is no longer constant as the specimen is defocused and varies with the curvature radii. FFT techniques enable the correcting procedure to be found and hence the redetermination of the exact acoustic properties.
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Single-mode InGaAs-GaAs laser diodes operating at 980 nm
  • Author(s): J.S. Major ; W.E. Plano ; D.F. Welch ; D. Scifres
  • Source: Electronics Letters, Volume 27, Issue 6, p. 539 –541
  • DOI:  10.1049/el:19910339
  • Type: Article
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  • p. 539 –541 (3)
    Data are presented describing the operation of single-transverse, single-longitudinal mode strained-layer InGaAs laser diodes operating at λ = 980 nm. These diodes exhibit single-transverse mode behaviour to beyond 210 mW continuous wave (CW) and single-longitudinal mode behaviour to beyond 150 mW CW. The maximum output power is approximately 350 mW CW. The threshold current of these lasers is ∼ 10 mA, with a differential quantum efficiency of 85%. The total efficiency of these diodes exceeds 50% at an output power of 100 mW.
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Enhancement of CF4 and O2 reactive ion etching resistance of poly(butene-1 sulfone) by N2 plasma pretreatment
Selfstarting, passively modelocked erbium fibre ring laser based on the amplifying Sagnac switch
Subpicosecond all-fibre erbium laser
New output voltage control technique using dynamic model for quantum series resonant convertor
Erratum: Chiroshield: a Salisbury/Dallenbach shield alternative
Erratum: Optimisation of LiNbO3 BOA waveguide switches operating at 1.3 μm

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