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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 15, Issue 23, 8 November 1979

Volumes & issues:

Volume 15, Issue 23

8 November 1979

Modal dispersion of optical fibres with a composite α-profile graded-index core
Mode dispersion of trapezoidal cross-section dielectric optical waveguides by the effective-index method
  • Author(s): J.G. Gallagher
  • Source: Electronics Letters, Volume 15, Issue 23, p. 734 –736
  • DOI:  10.1049/el:19790525
  • Type: Article
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  • p. 734 –736 (3)
    The mode dispersion of dielectric optical waveguides is calculated by the effective-index method and is compared with previously reported experimental and theoretical finite-element results for trapezoidal cross-section waveguides. Agreement between experimental and predicted results is very good. This is significant because it means that stripe waveguides can be designed with specific modal propagation properties using the much simpler effective-index method even though the waveguide cross-section is not rectangular.
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Optimal radix for monolithic memories
Tee-coupler for single-mode fibres
Picosecond optical pulse generation from an r.f. modulated AlGaAs d.h. diode laser
Compact dual-hybrid-mode feeds with low crosspolar radiation
Improvement of intermodulation distortion in microwave m.e.s.f.e.t. amplifiers using gate-bias compensation
  • Author(s): Ramesh K. Gupta ; Paul A. Goud ; Colin G. Englefield
  • Source: Electronics Letters, Volume 15, Issue 23, p. 741 –742
  • DOI:  10.1049/el:19790530
  • Type: Article
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  • p. 741 –742 (2)
    A simple technique is described for improving the intermodulation distortion performance of microwave m.e.s.f.e.t. amplifiers. The technique utilises transistor gate-bias compensation controlled by the input signal level of the amplifier. For a constant output power of 0 dBm, an improvement in third-order intermodulation distortion product of up to 10 dB has been observed. The advantages and limitations of the technique are discussed.
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n-channel formation on semi-insulating InP surface by m.i.s.f.e.t.
Synthesis and analysis of d.l.t.s. spectra from m.o.s. surface states
Integrated-circuit fabrication flaw detected using the supply-current analysis technique
800 Mb/s fibre transmission test using low-loss and low-dispersion single-mode cable
  • Author(s): Nakagawa Kiyoshi ; Hakamada Yoshiro ; Suto Koh-Ichi
  • Source: Electronics Letters, Volume 15, Issue 23, p. 747 –748
  • DOI:  10.1049/el:19790534
  • Type: Article
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  • p. 747 –748 (2)
    Error-rate performances of a single-mode fibre transmission system are evaluated at wavelengths of 1.18 and 1.31 μm. It is proven that longitudinal single-mode oscillation of the laser is important in a high-bit-rate system at a finite dispersion wavelength. At a low dispersion wavelength of 1.31 μm, repeater spacing at 800 Mb/s was extended to 40 km, by developing a low-loss single-mode fibre cable, a stabilised optical transmitter and receiver and a single-mode optical connector.
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Gettering of epitaxial gallium phosphide using phosphosilicate glass
Optical-fibre network system for air-pollution monitoring over a wide area by optical absorption method
  • Author(s): Humio Inaba ; Takao Kobayasi ; Masayuki Hirama ; Mostafa Hamza
  • Source: Electronics Letters, Volume 15, Issue 23, p. 749 –751
  • DOI:  10.1049/el:19790536
  • Type: Article
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  • p. 749 –751 (3)
    A low-loss optical-fibre network system for monitoring air pollution and species concentrations in various environments utilising the differential absorption method is proposed and discussed as a sensitive and economical as well as nonhazardous method. Its feasibility and advantages are also described on the basis of the present state of the art of the relevant technology.
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Surface reactance of corrugated planes
Evidence of trapping in device-quality liquid-phase-epitaxial In1−xGaxAsyP1−y
  • Author(s): P.K. Bhattacharya ; J.W. Ku ; S.J.T. Owen ; S.H. Chiao ; R. Yeats
  • Source: Electronics Letters, Volume 15, Issue 23, p. 753 –755
  • DOI:  10.1049/el:19790538
  • Type: Article
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  • p. 753 –755 (3)
    Traps have been identified in epitaxial n- and p-type In1−xGaxAsyP1−y for the first time. The activation energy, capture cross-section and density of several electron traps in the quaternary composition range from InP to In0.53Ga0.47As have been determined. An electron trap similar in some characteristics to the 0.83 eV electron trap present dominantly in bulk and v.p.e. GaAs was observed in an n-type In0.71Ga0.29As0.45P0.55(Eg=0.95 eV) layer. Hole traps were not observed.
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Analysis and measurement of modal noise in an optical fibre
Incorporation of bromine into Si-SiO2 interfaces and effects on interface state distribution
  • Author(s): T.C. Poon  and  H.C. Card
  • Source: Electronics Letters, Volume 15, Issue 23, p. 756 –757
  • DOI:  10.1049/el:19790540
  • Type: Article
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  • p. 756 –757 (2)
    An experimental study has been made of the effects of bromine treatment of (111) silicon surfaces before thermal oxidation. A sharp peak in the Si-SiO2 interface state distribution at Ev+ 0.15 eV and an overall increase in density by as much as two orders of magnitude has been observed in m.o.s. structures with SiO2 thickness of ≈ 100 Å. In a.c. conductance against bias voltage measurements, two conductance peaks are observed rather than the customary single peak.
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Low-loss optical Y-branch
Depletion-type m.o.s.f.e.t.s for low-temperature operation
  • Author(s): M. Kawashima ; M. Kanamori ; M. Matsumura
  • Source: Electronics Letters, Volume 15, Issue 23, p. 759 –760
  • DOI:  10.1049/el:19790542
  • Type: Article
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  • p. 759 –760 (2)
    Taking carrier freeze-out into account|a novel structure for depletion-type m.o.s.f.e.t.s suitable for low-temperature operation is proposed. Its channel consists of two regions; a relatively wide, low-impurity-density region and a relatively narrow, high-impurity-density region. It is estimated that the proposed structure has more square-law-like load character istics and higher current density than conventional ones.
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Effects of drop size and temperature on forward and backward scattering of microwaves by raindrops
  • Author(s): S.A.J. Upton ; B.G. Evans ; A.R. Holt
  • Source: Electronics Letters, Volume 15, Issue 23, p. 760 –762
  • DOI:  10.1049/el:19790543
  • Type: Article
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  • p. 760 –762 (3)
    An explanation is given for the peak sensitivity around 9–11 GHz to drop-size distribution and temperature of microwave attenuation due to a rain-filled medium. The sensitivity of radar reflectivity, differential radar reflectivity and differential radar cross-section to drop-size and temperature are also given. It is shown that at frequencies in excess of about 25 GHz the vertical radar cross-section of water drops can be greater than the horizontal.
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Propagation constants of guided modes in graded-index fibre with polynomial-profile core
Single-mode c.w. ridge-waveguide laser emitting at 1.55 μm
Minimum dispersion at 1.55 μm for single-mode step-index fibres
Reply: Minimum dispersion at 1.55 μm for single-mode step-index fibres

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