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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 13, Issue 9, 28 April 1977

Volumes & issues:

Volume 13, Issue 9

28 April 1977

Theoretical model for a microsctip optoelectronic switch
  • Author(s): A. Meriau ; R. Castagne ; R. Laval ; S. Laval
  • Source: Electronics Letters, Volume 13, Issue 9, p. 245 –246
  • DOI:  10.1049/el:19770177
  • Type: Article
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  • p. 245 –246 (2)
    A theoretical model is given to represent the active part of either an optoelectronic switch, similar to those described by Auston el al., or an optoelectronic gate such as the one we developed. These devices consist mainly of a microstrip line, with a characteristic impedance of 50 Ω, which is deposited on a high-resistivity semiconductor. The centre strip has a break, creating a gap which can be illuminated by an optical laser pulse. The latter generates an electron-hole plasma of high density at the surface of the semiconductor, allowing the transmission of a signal across the gap.
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Light-controlled semiconductor waveguide antenna
  • Author(s): R. Karg  and  E. Kreutzer
  • Source: Electronics Letters, Volume 13, Issue 9, p. 246 –247
  • DOI:  10.1049/el:19770178
  • Type: Article
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  • p. 246 –247 (2)
    A rectangular dielectric waveguide of intrinsic semiconductor material has been investigated for an application in the 30–40 GHz range. The resistivity of the semiconductor material has locally been changed by GaAs-laser-beam illumination. Depending on the pattern and intensity of the light spot, the generated waveguide inhomogeneity behaves essentially as a termination, a short circuit or an antenna element. This effect can be controlled in position and time. Hence the optically controlled waveguide can be used either as an antenna for fast aperture scanning or as a simple optoelectronically tuned antenna array.
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OH-ion distribution profiles in rod preforms of high-silica optical waveguide
Acoustic-bulk-wave resonators and filters operating in the fundamental mode at frequencies greater than 100 MHz
  • Author(s): M. Berté
  • Source: Electronics Letters, Volume 13, Issue 9, p. 248 –250
  • DOI:  10.1049/el:19770180
  • Type: Article
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  • p. 248 –250 (3)
    A localised ion-beam milling has been used to increase the fundamental frequency of acoustic-bulk-wave resonators. Monolithic filters in lithium niobate (Y+37°) and lithium tantalate (X) operating, respectively, at 220 and 230 MHz have been realised. The relative bandwidth is equal to 1% and the insertion loss is about 4 dB. An a.t.-cut quartz resonator working in the fundamental mode at 270 MHz with a Q-factor of 12 000 has also been obtained. In this case, the vibrating membrane is 6 μm thick, with a centre portion of diameter 2.5 mm.
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Expressions for the analysis of digital transmission systems
Utilisation of a single inductorless neuristor line section as a voltage-to-frequency convertor
  • Author(s): Z. Czarnul  and  M. Bialko
  • Source: Electronics Letters, Volume 13, Issue 9, p. 251 –252
  • DOI:  10.1049/el:19770182
  • Type: Article
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  • p. 251 –252 (2)
    The principle of operation of a neuristor line for input pulses having duration times longer than the refractory period of the line is presented. In this case, a series of neuristor pulses are generated and appear at the output of the line. The duration time of the generated pulse ‘package’ corresponds to the duration time of the input pulse, while the repetition frequency of pulses is proportional to the amplitude of the input pulse. Theoretical relations and practical verification of the circuit operation are described.
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Pattern-recognition properties of r.a.m./r.o.m. arrays
Method of obtaining radiowave propagation parameters for the Earth–ionosphere duct at e.l.f.
Pulse response and microbending losses of an optical glass-fibre waveguide with a bump in its index profile
  • Author(s): W. Eickhoff  and  O. Krumpholz
  • Source: Electronics Letters, Volume 13, Issue 9, p. 256 –257
  • DOI:  10.1049/el:19770185
  • Type: Article
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  • p. 256 –257 (2)
    It is shown that a short light pulse is split into two separate output pulses when transmitted through a graded-index fibre with a refractive-index bump in its centre. For the fibre investigated, the bump acts as a monomode waveguide. This monomode waveguide turned out to be much less sensitive to microbending than the multimode graded-index waveguide, which is in agreement with existing theories.
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Compensating fibre splice technique
Simple electronically tunable 2nd-order active filter
Second-harmonic locking properties of l.s.a.-mode transferred-electron oscillators
Effects of γ-irradiation on some cholesteric products
Figure of merit for avalanche photodiodes
  • Author(s): Hiroshi Kanbe  and  Tatsuya Kmura
  • Source: Electronics Letters, Volume 13, Issue 9, p. 262 –264
  • DOI:  10.1049/el:19770190
  • Type: Article
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  • p. 262 –264 (3)
    With regard to optimum signal/noise ratio at an optical receiver output, a figure of merit for an avalanche photodiode is proposed of the form η/√κ, where n is the quantum efficiency and k is the ratio of the hole ionisation coefficient β to that of an electron, α. An optimum avalanche-region width is estimated by using the figure of merit for a silicon avalanche photodiode at a given breakdown voltage.
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New television test waveform
Dielectric-clad discone
Microbending loss of multimode square-law fibres: a ray theory
Decision-directed reference carrier generation in an autocorrelation receiver
C.C.D. processor for simultaneous time stretching and signal averaging
  • Author(s): G.D. Cain  and  R.C.S. Morling
  • Source: Electronics Letters, Volume 13, Issue 9, p. 269 –270
  • DOI:  10.1049/el:19770195
  • Type: Article
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  • p. 269 –270 (2)
    A novel dual-C.C.D signal processor is described which operates on a periodic input signal in such a manner that the input undergoes time-scale stretching while also being reinforced in amplitude in direct proportion to the number of delay stages in the c.c.d.s composing the structure. The timescaling effect is beneficial, since the signal variations are slowed to permit subsequent lower-bandwidth processing and/or display. The amplitude reinforcement works to partially cancel out any attendant noise contamination, making this simple processor readily applicable where signal averaging is desired.
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C.C.D.-addressed liquid-crystal displays
Erratum: Maximum information capacity of fibre-optic waveguides
Erratum: Parallel-in/serial-out: a new approach for c.c.d. transversal filters
Erratum: Effect of vibration on s.a.w.-oscillator noise spectra
Comment on ‘Low-frequency behaviour of the Beverage aerial’

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