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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 22, Issue 5, 27 February 1986

Volumes & issues:

Volume 22, Issue 5

27 February 1986

Graded-index-type crystalline fibre for IR light transmission
  • Author(s): S. Kachi ; M. Kimura ; K. Shiroyama
  • Source: Electronics Letters, Volume 22, Issue 5, p. 230 –231
  • DOI:  10.1049/el:19860158
  • Type: Article
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  • p. 230 –231 (2)
    A new method for making a graded-index-type crystalline fibre is proposed. A fibre for IR light transmission with crystalline claddings was desired for improving the reliability of the crystallinc fibre and for avoiding any excess loss at the core surface. A fibre with the core-cladding structure was made by complex extrusion with KRS-5 as the core and KRS-6 as the cladding. Obtaining a smooth core-cladding interface was very difficult. This problem was overcome by a diffusion of composite ions by annealing after the extrusion. The fibre has a concentration distribution that can be accounted for by a GI fibre. The transmission loss of the CO2 laser is 0.2 dB/m with a launching NA of 0.05.
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11 W quasi-CW monolithic laser diode arrays
Loss of lock in long-loop phase-locked receivers in the presence of large interfering carrier
  • Author(s): S.D. Marougi
  • Source: Electronics Letters, Volume 22, Issue 5, p. 233 –234
  • DOI:  10.1049/el:19860160
  • Type: Article
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  • p. 233 –234 (2)
    In long-loop receivers, the inclusion of time delay within the loop causes significant modification in the loop's acquisition and synchronous behaviour. In the letter an investigation has been carried out to specify the signal-to-interference ratio required to bring the loop out of synchronism with a desired noise-free carrier. Results are displayed for long loops with different time delay, as well as for short-loop receivers.
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InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading and multiplication regions grown by metalorganic chemical vapour deposition
Ga0.47In0.53As field-effect transistors with a lattice-mismatched reduced leakage current GaAs gate
  • Author(s): P.A. Garbinski ; C.Y. Chen ; A.Y. Cho
  • Source: Electronics Letters, Volume 22, Issue 5, p. 236 –238
  • DOI:  10.1049/el:19860162
  • Type: Article
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  • p. 236 –238 (3)
    A lattice-mismatched GaAs gate Ga0.47In0.47As field-effect transistor (LMG-FET) with significantly reduced reverse gate leakage current is reported. The mechanism responsible for this reduction by over two orders of magnitude over previous work has been identified; it is attributed to the confinement of misfit dislocations originating at the GaAs/InGaAs interface. The LMG-FET had a gate leakage current of 0.48 μA at − V, and an extrinsic DC transconductance of 104 mS/ mm for a 1.4 μm gate length and 240 μm gate width. Further refinements in crystal growth should lead to even lower values of leakage current, making this technology attractive for high-speed logic, as well as lightwave optoelectronic integration.
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Fibre-optic thermometer using semiconductor-etalon sensor
Small-signal drain conductance of MOSFET in saturation region—a simple model
  • Author(s): F.S. Shoucair
  • Source: Electronics Letters, Volume 22, Issue 5, p. 239 –241
  • DOI:  10.1049/el:19860164
  • Type: Article
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  • p. 239 –241 (3)
    A simple expression is developed which determines an upper bound on the incremental drain conductance of the long-channel MOSFET in saturation. This expression may be used to estimate efficiently lower gain bounds of MOS gain stages at the hand analysis phase of analogue circuit designs. The accuracy achieved is comparable to that of currently used commercial simulators and to the data spread observed in current MOS processes. A criterion for ‘long’-channel behaviour in saturation is proposed.
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Schottky barriers on p-type gallium arsenide prepared by molecular beam epitaxy
Monolithic integration of InGaAs/InP DFB lasers and InGaAs/InAlAs MQW optical modulators
Modified phase-shift keying—a new line code for digital subscriber loops
MOS transconductors and integrators with high linearity
  • Author(s): Y. Tsividis ; Z. Czarnul ; S.C. Fang
  • Source: Electronics Letters, Volume 22, Issue 5, p. 245 –246
  • DOI:  10.1049/el:19860168
  • Type: Article
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  • p. 245 –246 (2)
    MOS transconductors are discussed in which the transistors determining the transconductance do not carry bias current, operate with large gate-source voltage, and are signal-driven in such a way that their nonlinearities are eliminated. An integrator implemented using one of the proposed circuits exhibited measured total harmonic distortion of less than 0.1% for differential input signals of 2.5 V p-p, and less than 1% for 5 V p-p.
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Measurements of impulse response of a wideband radio channel at 910 MHz from a moving vehicle
Electron transport across depleted region of a fine-gate GaAs:AlGaAs heterojunction FET
  • Author(s): T.J. Thornton ; M. Pepper ; H. Ahmed ; D. Andrews ; G.J. Davies
  • Source: Electronics Letters, Volume 22, Issue 5, p. 247 –249
  • DOI:  10.1049/el:19860170
  • Type: Article
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  • p. 247 –249 (3)
    The low-temperature characteristics of a depleted GaAs AlGaAs heterojunction FET with gate length of 1000 Å and width 10 μm show that the current is initially space-charge- limited. The onset of velocity saturation is observed as the source-drain bias is increased. The structure in the differential of resistance is attributed to the emission of optic phonons by hot electrons.
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Band-structure engineering for low-threshold high-efficiency semiconductor lasers
Low dissipation current GaAs prescaler IC
Novel Ti:LiNbO3 linear mode confinement modulator
Optical System with two packaged 1.5 μm semiconductor laser amplifier repeaters
Influence of bias current and signal power on behaviour of an antireflection-coated laser amplifier
Integrated low-noise lasers
Application of multi-objective optimisation to compensator design for SISO control systems
Broadband GaAs FET optical front-end circuit up to 5.6 GHz
  • Author(s): N. Ohkawa ; J.-I. Yamada ; K. Hagimoto
  • Source: Electronics Letters, Volume 22, Issue 5, p. 259 –260
  • DOI:  10.1049/el:19860178
  • Type: Article
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  • p. 259 –260 (2)
    Design and performance of transimpedance preamplifiers for multi-gigabit/s optical repeaters are reported using 0.3 μm gate length GaAs FETs and a Ge-APD with a sensitive area of 30 μm diameter. Through reduction of parasitic inductance and stray capacitance in chip assembly, a 3 dB down bandwidth of 8.2 GHz is achieved without a Ge-APD. A 3 dB down bandwidth of 5.6 GHz and good pulse response to 6.5 Gbit/s RZ pattern optical signals are achieved in an optical front-end circuit with a Ge-APD.
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Comparison between pseudomode and radiation mode methods for deriving microbending losses
Effect of ambient water vapour on stability of lithium niobate electro-optic waveguide devices
Measurement of on-chip waveforms and pulse propagation in digital GaAs integrated circuits by picosecond electro-optic sampling
  • Author(s): X.-C. Zhang  and  R.K. Jain
  • Source: Electronics Letters, Volume 22, Issue 5, p. 264 –265
  • DOI:  10.1049/el:19860181
  • Type: Article
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  • p. 264 –265 (2)
    We demonstrate precise measurement of sub-100 ps rise time on-chip electrical waveforms and of pulse propagation in digital GaAs integrated circuits with the use of picosecond electro-optic sampling. These experiments yield the first non-invasive measurement of single-gate propagation delays via direct and precise observation of on-chip waveforms at the input and output of individual logic gates internal to an integrated circuit.
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Optical switching of a GaAs triangular barrier switch grown by MBE
Sapphire resonator
Mode-locking of a neodymium-doped monomode fibre laser
  • Author(s): I.P. Alcock ; A.I. Ferguson ; D.C. Hanna ; A.C. Tropper
  • Source: Electronics Letters, Volume 22, Issue 5, p. 268 –269
  • DOI:  10.1049/el:19860184
  • Type: Article
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  • p. 268 –269 (2)
    A neodymium-doped monomode fibre laser operating at 1.08 pm has been actively mode-locked usmg intracavity acousto-optic loss modulation. The mode-locked laser output consisted of a train of pulses of less than 1 ns FWHM with an energy of ∼ 17 pJ at a repetition rate of 41.45 MHz. When the laser was simultaneously Q-switched the peak power of the mode-locked pulses inside the 690 ns-wide envelope was enhanced by more than three orders of magnitude.
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Error-correcting coding for banking document bar codes
Field dependence of drift velocity and electron population in satellite valleys in gallium arsenide
  • Author(s): V. Choudhry  and  V.K. Arora
  • Source: Electronics Letters, Volume 22, Issue 5, p. 271 –272
  • DOI:  10.1049/el:19860186
  • Type: Article
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  • p. 271 –272 (2)
    We present, for the first time, simple explicit expressions for the drift velocity and the electron population in the many-valley band structure of n-type gallium arsenide. It is shown that all the experimentally observed features could be well explained if mean-free-path values of 150 nm and 700 nm in the two sets of valleys are assumed. It is indicated that the mobilities of high-mobility valleys are rapidly degraded with the increase in the electric field. The novel results so obtained could be usefully applied in the design and development of semiconducting devices with two or more energy level structures.
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Statistical antenna gain description of randomly distorted reflectors
Minimum switches and connection procedure for eight telephone lines
Simple analysis of external optical feedback in DFB semiconductor lasers
Spin-on diffused GaSb mesa photodiode with high breakdown voltages
All-fibre-optic logic ‘AND’ gate
High-power GaAlAs window lasers
  • Author(s): J. Ungar ; N. Bar-Chaim ; I. Ury
  • Source: Electronics Letters, Volume 22, Issue 5, p. 279 –280
  • DOI:  10.1049/el:19860192
  • Type: Article
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  • p. 279 –280 (2)
    High-power GaAlAs lasers using the large optical cavity buried-heterostructure (LOC-BH) window structure, which provides transverse index guiding in the nonabsorbing facet region, have been fabricated. Threshold currents between 30 and 50 mA and differential quantum efficiencies of 0.85 mW/ mA have been measured. CW and pulsed output powers up to 88 and 372 mW, respectively, have been attained.
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New programmable switched-capacitor filter
Dispersion characteristics of unsymmetrical broadside-coupled striplines with anisotropic substrate
  • Author(s): T. Kitazawa ; A. Muranishi ; Y. Hayashi
  • Source: Electronics Letters, Volume 22, Issue 5, p. 281 –283
  • DOI:  10.1049/el:19860194
  • Type: Article
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  • p. 281 –283 (3)
    Dispersion characteristics of the unsymmetrical broadside-coupled striplines of unequal width are presented for the first time. The frequency-dependent hybrid-mode solutions converge to the quasistatic values at lower frequencies for various structural parameters of the broadside-coupled suspended striplines (BCSSs) and broadside-coupled inverted striplines (BCISs) with the anisotropic substrates.
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Performance of ASK heterodyne detection for various laser linewidths
  • Author(s): Y.K. Park ; J.-M.P. Delavaux ; N.A. Olsson ; T.V. Nguyen ; D.E. Tamburino ; R.W. Smith ; S.K. Korotky ; M. Dixon
  • Source: Electronics Letters, Volume 22, Issue 5, p. 283 –284
  • DOI:  10.1049/el:19860195
  • Type: Article
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  • p. 283 –284 (2)
    We report the dependence of receiver sensitivity on laser linewidth for a series of ASK heterodyne experiments performed with 1.5 μm distributed feedback lasers and external cavity lasers, and the result of an error-free heterodyne transmission experiment at 150 Mbit/s over 102 km of fibre using the external cavity lasers.
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Low resistance alloyed NiGeAuAgAu ohmic contacts to modulation-doped Al0.48In0.52As/Ga0.47In0.53As
  • Author(s): P.M. Capani ; S.D. Mukherjee ; H.T. Griem ; L. Rathbun ; L.F. Eastman
  • Source: Electronics Letters, Volume 22, Issue 5, p. 285 –286
  • DOI:  10.1049/el:19860196
  • Type: Article
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  • p. 285 –286 (2)
    A low-resistance ohmic-contacts metallurgy has been developed for the modulation-doped Al0.48In0.52As/Ga0.47In0.53As structure for MODFET (HEMT) application. The metallurgy involves we sequentially evaporated NiGeAuAgAu layers followed by transient thermal alloy cycles. This resulted in low transfer resistance ∼ 0.20 ± 0.05 Ω mm to the two dimensional electron gas for alloying temperatures from 410° C to 500°C.
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New frame synchroniser for satellite-switched time-division multiple-access systems
Performance of interconnections laid on insulating and MIS substrates
  • Author(s): C. Seguinot ; P. Kennis ; P. Pribetich
  • Source: Electronics Letters, Volume 22, Issue 5, p. 287 –289
  • DOI:  10.1049/el:19860198
  • Type: Article
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  • p. 287 –289 (3)
    Crosstalk phenomena and pulse propagation in coupled microstrip lines are analysed. Results obtained with insulating substrates and MIS structures are compared. The method of analysis can also be applied to the modelling of Schottky contact interconnection lines. These first investigations point out the necessity to define new structures owing to the reduction of crosstalk phenomena in MMICs.
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