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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 23, Issue 8, 9 April 1987

Volumes & issues:

Volume 23, Issue 8

9 April 1987

Local beam deflector interated in a diode laser cavity
Narrow, high-NA GaAs/GaAlAs optical waveguides with losses below 0.7±0.1 dB cm-1
Electromigration effects in power MESFET rectifying and ohmic contacts
Comparison of two statistical tests for keystream sequences
Performance of a GaAlAs laser diode used for multichannel video transmission employing multiplexed UHF subcarriers
Increasing the bandwidth of a microstrip antenna by proximity coupling
  • Author(s): D.M. Pozar  and  B. Kaufman
  • Source: Electronics Letters, Volume 23, Issue 8, p. 368 –369
  • DOI:  10.1049/el:19870270
  • Type: Article
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  • p. 368 –369 (2)
    The letter presents experimental results for a proximity-coupled microstrip patch antenna capable of 13% bandwidth. The impedance match (VSWR ≤ 2), copolarised radiation patterns and crosspolarised radiation were measured over this bandwidth to confirm operation. The construction is quite simple, consisting of a microstrip feedline on a substrate proximity-coupled to a rectangular microstrip patch on a covering superstrate; a small open-circuit tuning stub is connected in shunt with the feed line.
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New high-resolution positive and negative photoresist method for λ/4-shifted DFB lasers
  • Author(s): M. Okai ; S. Tusji ; M. Hirao ; H. Matsumura
  • Source: Electronics Letters, Volume 23, Issue 8, p. 370 –371
  • DOI:  10.1049/el:19870271
  • Type: Article
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  • p. 370 –371 (2)
    High-resolution positive and negative photoresists were used to fabricate λ/4-phase-shifted corrugations by holographic exposure. To avoid mixing these photoresists, cyclised polyisoprene was used as a midlayer. The shape and depth of the corrugations on the positive and negative photoresist regions were almost the same. Single-mode operation at the Bragg wavelength was confirmed in lasers with the corrugation.
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Low-threshold, high-power zero-order lateral-mode DQW-SCH metal-clad ridge waveguide (AlGa)As/GaAs lasers
  • Author(s): B. Garrett  and  R.W. Glew
  • Source: Electronics Letters, Volume 23, Issue 8, p. 371 –373
  • DOI:  10.1049/el:19870272
  • Type: Article
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  • p. 371 –373 (3)
    Metal-clad ridge waveguide (MCRW), double quantum well, separately confined heterostrucuture (DQW-SCH) lasers have been fabricated having continuous-wave (CW) threshold currents of 10–12 mA and external differential quantum efficiencies of 41–46% per uncoated facet. Light/current characteristics are linear to >70 mW, and zero-order lateral mode operation was measured at 56 mW. The CW burn-off power density is nearly double the best previously reported value.
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Fields in a bent single-mode fibre
  • Author(s): S.J. Garth
  • Source: Electronics Letters, Volume 23, Issue 8, p. 373 –374
  • DOI:  10.1049/el:19870273
  • Type: Article
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  • p. 373 –374 (2)
    Gaussian functions are commonly used to approximate the fundamental mode field in a straight fibre. If used as a basis for perturbation theory in a bent fibre, then the perturbation terms can be summed to all orders to give a new expression for the field and propagation constant in a bent fibre. These expressions are not the usual first-order corrections to the unperturbed quantities, and not restricted by the magnitude of the perturbation. The expression for field shift is compared to experimentel results.
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Gigabit optical transmitter GaAs MESFET IC
Geometrical design considerations for a tree-structured optical switch matrix
Four-port homodyne receiver for optical fibre communications comprising phase and polarisation diversities
Polarisation state stabilisation in optically nonlinear birefringent fibres
Heterostructure complementary technology
Selective formation of ohmic contacts to n-GaAs
  • Author(s): Y. Yamane ; Y. Takahashi ; H. Ishii ; M. Hirayama
  • Source: Electronics Letters, Volume 23, Issue 8, p. 382 –383
  • DOI:  10.1049/el:19870279
  • Type: Article
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  • p. 382 –383 (2)
    A new process is presented for ohmic contact realisation to n-GaAs. The process enables selective formation of ohmic contacts showing ohmic characteristics without an alloying process. This is realised through the deposition of a heavily doped n-Ge layer on an n-GaAs layer. It is possible to grow a Ge layer on GaAs without deposition on SiO2 which is used as a mask. A Ge layer with doping in excess of 1019 cm−3 can be obtined, using GeH4, PH3 and H2 as source gases. This doping level is sufficiently high to exhibit nonalloyed ohmic characteristics.
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Spice simulation of laser diode modules
Transverse junction buried heterostructure (TJ-BH) AlGaAs diode laser
Transmission at 1 Gbit/s over 7.4 km of single-mode fibre using an edge-emitting LED and PINFET receiver
Generation of a wide circularly polarised wave from a conical-helix antenna
  • Author(s): H. Nakano ; M. Sato ; J. Yamauchi
  • Source: Electronics Letters, Volume 23, Issue 8, p. 387 –388
  • DOI:  10.1049/el:19870283
  • Type: Article
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  • p. 387 –388 (2)
    The optimum pitch and cone angles of a conical-helix antenna are numerically investigated from the viewpoint of widening a circularly polarised beam. It is found that the helices of a cone angle of 5° with pitch angles ranging from 40° to 45° realise a circularly polarised beam over a hemispherical region. It is also found that an antenna height of at least one wavelength is required to maintain a circularly polarised beam of more than 160°.
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Front-to-back ratio of a smooth metallic-wall conical horn
Tunable single-mode output of a multimode laser in a tunable fibre grating external cavity
Matrix approach for the coefficients of maximally flat FIR filter transfer functions expressed in powers of cos w
Linewidth reduction in DFB laser by detuning effect
MBE-grown AlGaAs/GaAs HBTs on InP substrate
Signal gain saturation in two-channel common amplification using a 1.5μm InGaAsP travelling-wave laser amplifier
  • Author(s): T. Mukai ; K. Inoue ; T. Saitoh
  • Source: Electronics Letters, Volume 23, Issue 8, p. 396 –397
  • DOI:  10.1049/el:19870289
  • Type: Article
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  • p. 396 –397 (2)
    Signal gain saturation and crosstalk characteristics in two-channel common amplification were investigated using a 1.5μm travelling-wave laser amplifier. Simultaneous amplification in the two channels causes gain saturation of the other, which results in an approximate 3 dB reduction in saturation output power. The total output power is confirmed to dominate the gain saturation in laser amplifiers.
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10 GHz space power combiner with parasitic injection locking
  • Author(s): R.J. Dinger ; D.J. White ; D.R. Bowling
  • Source: Electronics Letters, Volume 23, Issue 8, p. 397 –398
  • DOI:  10.1049/el:19870290
  • Type: Article
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  • p. 397 –398 (2)
    An array of three microstrip patch antennas, each connected by a matching network to an impatt diode, has been investigated. Coherent radiation from the array was obtained at 10.2GHz by feeding only the centre element with an injection-locking signal, which then appeared at the input to the other two elements by free-space mutual coupling. The three impatts injection-locked successfully, producing a broadside beam with a width of 38°. An RF efficiency of 86% was measured.
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Absolute-type shaft encoder using shift register sequences
1.3 μm 35 km fibre-optic microwave multicarrier transmission system for satellite Earth stations
GaAs monolithic microwave integrated circuit trimming using laser-direct-written tungsten microstrip lines
  • Author(s): C.L. Chen ; J.G. Black ; L.J. Mahoney ; S.P. Doran ; W.E. Courtney ; D.J. Ehrlich ; R.A. Murphy
  • Source: Electronics Letters, Volume 23, Issue 8, p. 402 –403
  • DOI:  10.1049/el:19870293
  • Type: Article
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  • p. 402 –403 (2)
    Laser-direct-write deposition of tungsten has been investigated as a technique for postfabrication trimming of GaAs monolithic microwave integrated circuits. Tungsten microstrip lines of 30 μΩ cm resistivity are deposited via a vapour-phase reaction induced by a focused argon-ion laser beam Lines of 1.8 μm thickness and 50μm width written on a semi-insulating GaAs substrate have a loss of 2.6 dB/cm at 16GHz. This trimming technique is proposed as a practical and accurate method for the optimisation of high-frequency GaAs circuits.
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Over 720 Ghz (5. 8nm) frequency tuning by a 1.5 μm DBR laser with phase and Bragg wavelength control regions
Semiconductor-doped fibre waveguides exhibiting picosecond optical nonlinearity
Using oxide sidewall taper to improve breakdown voltage in planar junction of DMOS devices by a simple process
  • Author(s): C.Y. Lu ; P.C. Riffe ; N.S. Tsai ; R.E. Ahrens ; M.A. Banak
  • Source: Electronics Letters, Volume 23, Issue 8, p. 407 –408
  • DOI:  10.1049/el:19870296
  • Type: Article
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  • p. 407 –408 (2)
    Argon ion implantation was used to create a damaged surface layer on field oxide. Subsequent oxide etching created a tapered oxide transition from thin oxide to thick field oxide. This structure effectively improves the breakdown voltage of the planar junction of a DMOS device which makes use of a poly field plate to enhance the breakdown voltage. The process is simple, reproducible and introduces no new mask steps.
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Probabilistic compaction algorithm for LSI cell layout design
  • Author(s): A. Onozawa ; H. Miyashita ; K. Ueda
  • Source: Electronics Letters, Volume 23, Issue 8, p. 408 –410
  • DOI:  10.1049/el:19870297
  • Type: Article
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  • p. 408 –410 (3)
    A compaction algorithm is presented that compacts LSI cell layout in a probabilistic manner. The algorithm is based on the constraint graph where the edge length is iteratively changed probabilistically using parameters and random numbers. Some experimental results show that an area reduction of from 2% to 20% can be achieved in comparison with the conventional compaction algorithm. The algorithm can also control the aspect ratio of the compacted layout.
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Methods for fine-tuning the wavelength response of single-mode optical-fibre taper filters
New interpretation of structure of thermally grown silicon dioxide
Serial/parallel automultiplier
  • Author(s): S.G. Smith
  • Source: Electronics Letters, Volume 23, Issue 8, p. 413 –415
  • DOI:  10.1049/el:19870300
  • Type: Article
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  • p. 413 –415 (3)
    Certain variations of the familiar serial/parallel multiplier architecture produce full-precision serial output at low area cost. However, logic gates included to form partial products and clear the accumulator between product calculations contribute to hardware complexity, and impair performance. A novel multiplication architecture—the ‘automultiplier’— pipelines the formation of partial products and dispenses with gating in the critical sum and carry paths internal to the array, reducing the computational element to the minimum full-adder at each stage. The automultiplier is so-called because its accumulator is automatically reset in the final cycles of a product calculation, and thus requires no internal hardware for initialisation. The resulting low-complexity multiplier array may sustain maximally high clocking rates.
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In0.53Ga0.47As PIN photodiode grown by MOVPE on a semi-insulating InP substrate for monolithic integration
0°-phase-shift, single-lobe operation from wide-waveguide interferometric (WWI) phase-locked arrays of InGaAsP/InP (λ = 1.3 μm) diode lasers
Analysis of threshold current density in 2.2 μm GaInAsSb/GaAlAsSb/GaSb DH lasers
  • Author(s): P. Brosson ; J. Benoit ; A. Joullie ; B. Sermage
  • Source: Electronics Letters, Volume 23, Issue 8, p. 417 –419
  • DOI:  10.1049/el:19870303
  • Type: Article
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  • p. 417 –419 (3)
    From comparison of published experimental data with a theoretical model of GaInAsSb/GaAlAsSb/GaSb DH lasers emitting at 2.2 μm, the Auger coefficient of the active material has been determined to be C ≈ 10−28 cm6S−1. A threshold current density as low as 2 kA/cm2 is expected at 300 K for such a DH with a 0.3 μm-thick active layer and confinement layers with a high aluminium content (x = 0.6).
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Bistable optical switching and logic elements in photochromic fulgides with single-wavelength illumination
Heterodyne transmission of a 560 Mbit/s optical signal by means of polarisation shift keying
Generalised subcomplementary sets of sequences
Electro-optic effect in He+-implanted optical waveguides in LiNbO3
High-speed GaAs 4×4-bit parallel multiplier using super capacitor FET logic
Uncertainty in deriving phase information from far-field modulus only
Spike-free switched-capacitor circuits
Finite-element solution of arbitrarily nonlinear, graded-index slab waveguides
  • Author(s): K. Hayata ; M. Koshiba ; M. Suzuki
  • Source: Electronics Letters, Volume 23, Issue 8, p. 429 –431
  • DOI:  10.1049/el:19870311
  • Type: Article
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  • p. 429 –431 (3)
    Dispersion relations for TE modes in arbitrarily nonlinear, graded-index slab waveguides are solved numerically by the finite-element method. In this approach, self-consistent solutions can be obtained by a simple iteration. It is shown that a small deviation from the Kerr-type nonlinear effect gives rise to a drastic change in the power-dependent behaviour of guided waves. The dependence of dispersion relations on the refractive-index profile of the film is also examined.
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