Showing papers in "Electronics Letters in 1977"
TL;DR: In this article, 15 different electron traps have been characterised in v.l.p. experiments and an accurate description of each level is given, and allows a fruitful comparison with fragmentary previous data.
Abstract: Fifteen different electron traps have been characterised in v.p.e., l.p.e., m.b.e. and bulk-grown GaAs from d.l.t.s. experiments. An accurate description of each level is given, and allows a fruitful comparison with fragmentary previous data. A catalogue of these electron traps is provided as a working tool.
654 citations
TL;DR: In this article, a catalogue of hole traps can be found for the assessment of the impurity contamination in a material, particularly for the estimation of the presence of different impurities, some of which are identified.
Abstract: Twelve different hole traps have been characterised in v.p.e., 1.p.e., m.b.e. and bulk-grown GaAs from d.1.t.s. experiments. Most are related to the presence of different impurities, some of which are identified. Although far from complete, this catalogue of hole traps can be a working tool, particularly for the assessment of the impurity contamination in a material.
246 citations
TL;DR: In this paper, an algorithm for the identification of nonlinear systems which can be described by a Wiener model consisting of a linear system followed by a single-valued nonlinearity is presented.
Abstract: An algorithm for the identification of nonlinear systems which can be described by a Wiener model consisting of a linear system followed by a single-valued nonlinearity is presented. Crossconolation techniques are employed to decouple the identification of the linear dynamics from the characterisation of the nonlinear element.
116 citations
TL;DR: In this article, slow-wave coplanai striplines on GaAs substrates with m.i.t.s. or Schottky junctions are described.
Abstract: Novel slow-wave coplanai striplines on GaAs substrates with m.i.s. or Schottky junctions are described. With these lines, significant reductions in wavelength and bias-dependent behaviours can be achieved at microwave frequencies. The new lines seem potentially very useful for monolithic integration of microwave circuits involving GaAs m.e.s.f.e.t.s.
104 citations
TL;DR: In this paper, a simple and fast non-destructive method of measuring the index profile of an optical-fibre preform is presented, where a laser beam is shone perpendicularly to the preform axis, and the exit angle of its backscattered ray is recorded as a function of the distance of the incident ray from the horizontal axis.
Abstract: A simple and fast nondestructive method of measuring the index profile of an optical-fibre preform is presented. In this method, a laser beam is shone perpendicularly to the preform axis, and the exit angle of its backscattered ray is recorded as a function of the distance of the incident ray from the horizontal axis. A numerical integration involving these exit angles gives the profile.
99 citations
TL;DR: In this paper, a simplified design-oriented equivalent circuit for the GaAs m.e.t.s. is presented, and its relation to a common, but more complex, model is derived and characteristics are compared.
Abstract: A simplified design-oriented equivalent circuit for the GaAs m.e.s.f.e.t. is presented. Its relation to a common, but more complex, model is derived and characteristics are compared. Element values are easily determined from measurements, and the simple model shows good agreement with measured parameters to 10 GHz for 1 μm-gate m.e.s.f.e.t.s.
84 citations
TL;DR: In this paper, an approximate theoretical relationship between rain depolarization and attenuation, valid for Earth-space paths at microwave and millimetre wavelengths, is presented, and the relationship is sufficiently general that it allows the prediction of rain-depolarisation statistics from attenuation statistics available for other frequencies, polarisations and elevation angles.
Abstract: An approximate theoretical relationship between rain depolarisation and attenuation, valid for Earth-space paths at microwave and millimetre wavelengths, is presented. The relationship is sufficiently general that it allows the prediction of rain-depolarisation statistics from attenuation statistics available for other frequencies, polarisations and elevation angles.
81 citations
TL;DR: In this paper, the limit for single-mode operation in a graded-index fiber was obtained by calculating the normalised cut-off frequency of the TE01 mode, and the affect of diffusion at the core-cladding boundary has been estimated.
Abstract: The limit for single-mode operation in a graded-index fibre has been obtained by calculating the normalised cut-off frequency of the TE01 mode, The affect of diffusion at the core-cladding boundary has been estimated.
76 citations
TL;DR: In this paper, the application of a GaAs m.e.t.s.d. detector as a high-speed optical detector has been investigated and compared with the result of a fast a.f.
Abstract: The application of a GaAs m.e.s.f.e.t. as a high-speed optical detector has been investigated and compared with the result of a fast a.p.d.
75 citations
TL;DR: In this paper, a computer program was implemented to calculate antenna far fields from spherical near-field measurements on a satellite model, and the accuracy of the computed far field is significantly improved, compared with the results obtained without probe correction.
Abstract: Probe correction has been implemented in a computer program which calculates antenna far fields from spherical nearfield measurements. The computer program has been applied to near-field measurements on a satellite model, and the accuracy of the computed far field is significantly improved, compared with the results obtained without probe correction.
74 citations
TL;DR: In this paper, a design procedure for millimetre waveguide-to-microstrip transitions is presented, which can be adapted to all physically realisable microstrip impedances, as well as substrate materials and thicknesses.
Abstract: A design procedure for millimetre waveguide-to-microstrip transitions is presented. The analysis is such that existing design information, readily available in practical curve format, can be directly applied. In addition, the procedure can be adapted to all physically realisable microstrip impedances, as well as substrate materials and thicknesses.
TL;DR: In this article, the interaction between coherent light propagating along an optical fiber and an acoustic wave incident on the fiber is described, and experimental measurements of the sensitivity are in sensible agreement with the theoretical predictions.
Abstract: The letter describes the interaction between coherent light propagating along an optical fibre and an acoustic wave incident on the fibre. The pressure sensitivity of a single-mode fibre is such that it may be used as a sensitive microphone with a very wide dynamic range. The corresponding effect in multimode fibres is a much more complex process, resulting in a reduction in both sensitivity and linearity. Experimental measurements of the sensitivity are in sensible agreement with the theoretical predictions.
TL;DR: In this article, the wave impedance of the Earth-ionosphere duct is investigated numerically and analytically in the frequency band 1 to 60 Hz in order to determine the propagation parameters of the duct.
Abstract: The wave impedance of the Earth-ionosphere duct is investigated numerically and analytically in the frequency band 1 to 60 Hz. Data are presented enabling the determination of the propagation parameters of the duct by experimental measurement of the argument of the wave impedance.
TL;DR: Pulse delay measurements on fibres are reported, made over a wide wavelength range straddling the zero of material dispersion as discussed by the authors, indicating that the optimum wavelength depends on the concentration for fibres containing germania.
Abstract: Pulse delay measurements on fibres are reported, made over a wide wavelength range straddling the zero of material dispersion. Results for phosphosilicate and a range of germania doped fibres indicate that the wavelength of negligible material dispersion lies in the range 1270-1400 nm. The optimum wavelength depends on the concentration for fibres containing germania.
TL;DR: In this paper, a bandpass filter and a discriminator for r.f. signals have been constructed by using fiber-optic delay lines, and their frequency-response characteristics have been investigated.
Abstract: A bandpass filter and a discriminator for r.f. signals have been constructed by using fibre-optic delay lines, and their frequency-response characteristics have been investigated. Both devices had a fundamental frequency of 193 MHz, and the filter had a 3 dB passband of 10 MHz.
TL;DR: In this article, a double-heterostructure InP/GaAsP/lnP high-radiance l.d.s have been fabricated by liquid-phase epitaxy on the face of commercially available InP substrates.
Abstract: Double-heterostructure InP/lnGaAsP/lnP high-radiance l.e.d.s have been fabricated by liquid-phase epitaxy on the face of commercially available InP substrates. The best small-area l.e.d.s had a useful external power efficiency of 1.5% and a 900 A-wide emission spectrum centred at 1.23 μm. emitting ∼3 mW into the air at 100 mA and 2 V; essentially similar results were obtained with devices operating al 1.30 μm.
TL;DR: In this paper, it was shown that a 2nd-order effect proportional to the square of the source spectral width determines the lower limit to fiber pulse spreading, and the optimum operating wavelength depends on the V-value of the guide.
Abstract: For the region of ‘zero material dispersion’, it is shown that a 2nd-order effect proportional to the square of the source spectral width determines the lower limit to fibre pulse spreading. The optimum operating wavelength depends on the V-value of the guide.
TL;DR: The insertion loss for multibar magnetostatic surface-wave (m.s.w) transducers has been calculated from a "small" loss microstrip-transmission line model as mentioned in this paper.
Abstract: The insertion loss for multibar magnetostatic-surface-wave (m.s.s.w.) transducers has been calculated from a ‘small’-loss microstrip-transmission-line model. Experimental results for 2-bar and 8-bar parallel-strip and 4-bar π transducers are in excellent agreement with theoretical predictions. The 8-bar parallel-strip-transducer delay line gives a major bandpass response at 3.1 GHz, corresponding to an m.s.s.w. wavelength of 300 μm. The insertion loss is 11 dB, the 10 dB bandwidth is 70 MHz and adjacent sidelobes are 16 dB down.
TL;DR: An important new family of acoustic wave devices is described in this article, which has the simplicity, versatility and planar construction of s.a.w. devices, together with the attractive properties of bulk-wave devices, including high velocity, low attenuation, good temperature stability and insensitivity to surface contamination.
Abstract: An important new family of acoustic wave devices is described which has the simplicity, versatility and planar construction of s.a.w. devices, together with the attractive properties of bulk-wave devices, including high velocity, low attenuation, good temperature stability and insensitivity to surface contamination.
TL;DR: In this article, a teachnique is described for generating the sine function with high accuracy from an analogue angle input, which can operate over any number of quadrants without switching high bandwidth and circuit simplicity.
Abstract: Bipolar circuits are described for generating the sine function with high accuracy from an analogue angle input. The teachnique offers operation over any number of quadrants without switching high bandwidth and circuit simplicity. The identity of the sine to a summation of tanh terms is utilised, a proof of which is provided.
IBM1
TL;DR: These polynomial transforms have the circular convolution property and can be used for the fast computation of 2-dimensional cyclic convolutions and yields efficient algorithms for the implementation of 1- and 2- dimensional digital filters.
Abstract: We define discrete transforms in a ring of polynomials. These polynomial transforms have the circular convolution property and can be used for the fast computation of 2-dimensional cyclic convolutions. This yields efficient algorithms for the implementation of 1- and 2-dimensional digital filters.
TL;DR: In this paper, the results obtained with laboratory transmission experiments on high-speed digital signals by optical wavelength-division multiplexing, using a newly developed optical multiplexer and demultiplexer, as well as other high-performance optical devices and fibres.
Abstract: The letter reports results obtained with laboratory transmission experiments on high-speed digital signals by optical wavelength-division multiplexing, using a newly developed optical multiplexer and demultiplexer, as well as other high-performance optical devices and fibres.
TL;DR: In this paper, a GeO 2 -doped silica singlemode optical fiber with a low attenuation loss of 0.5 dB/km at 1.27 μm, where the material dispersion of the silica glass falls to zero, has been made by a C.V.D. technique.
Abstract: A GeO
2
-doped silica single-mode optical fibre with a low attenuation loss of 0.5 dB/km at 1.27 μm, where the material dispersion of the silica glass falls to zero, has been made by a C.V.D. technique. Attention was paid to reducing OH absorption losses in the single-mode fibre.
TL;DR: In this article, the electrical properties of m.i.s. structures based on InP and Langmuir films have been investigated and a strongly inverted low-frequency-type C/V response occurs at about 30 Hz.
Abstract: The electrical properties of m.i.s. structures based on InP and Langmuir films have been investigated. A strongly inverted low-frequency-type C/V response occurs at about 30 Hz. Surface-state distributions have been evaluated by using both quasistatic and conductance techniques. Effective surface-state densities are found to be ~3 × 1011cm?2 eV?1 over a large fraction of the band gap.
TL;DR: In this paper, a combination of a cylindrical lens and a Selfoc lens was used to achieve a coupling loss nearly as low as 0.6 dB, which is the lowest known coupling loss.
Abstract: A new efficient coupling circuit, using a combination of a cylindrical lens and a Selfoc lens, which can be mounted in a laser package, has attained a coupling loss nearly as low as 0·6 dB.
TL;DR: The performance of the 3-op-amp instrumentation amplifier is analysed and shown to be, in general, no better than that of a single-op -amp differential amplifier.
Abstract: The c.m.r.r. performance of the 3-op-amp instrumentation amplifier is analysed and shown to be, in general, no better than that of a single-op-amp differential amplifier. Only under rather special conditions does the more elaborate amplifier have a c.m.r.r. advantage.
TL;DR: In this article, a continuous tuning of the oscillation frequency of a continuous-wave Raman fiber-optic laser has been demonstrated over a 3 nm band in the visible range and exhibits low threshold and high conversion efficiency.
Abstract: Continuous tuning of the oscillation frequency of a continuous-wave Raman fibre-optic laser has been demonstrated. The device operates over a 3 nm band in the visible range and exhibits low threshold and high conversion efficiency.
TL;DR: For controllable and observable linear multivariable systems, the set of transmission zeros is characterised in terms of the elements of ker [A-λI, B] as discussed by the authors.
Abstract: For controllable and observable linear multivariable systems, the set of transmission zeros is characterised in terms of the elements of ker [A-λI, B]. This characterisation greatly facilitates the determination of repeated transmission zeros or transmission zeros which coincide with poles of the transfer function matrix G(λ), and is universally applicable regardless of the rank of CB.
TL;DR: In this article, the growth and electrical properties of oxides grown on GaAs at 510°C were studied and it was shown that growth with time follows a parabolic law.
Abstract: The growth and electrical properties of oxides grown on GaAs at 510°C have been studied. Results show that growth with time follows a parabolic law and that electrical properties are, in general, very different from those of oxides grown anodically.
TL;DR: In this paper, it was shown that a constant-parameter dynamic system does not commute with a time-varying dynamic system, and conditions were derived for low-order time-variate systems to commute.
Abstract: Results are given concerning the commutativity of time-varying systems. It is shown that a constant-parameter dynamic system does not commute with a time-varying dynamic system. Conditions are derived for low-order time-varying systems to commute. A general condition for a set of time-varying systems to commute is the existence of a variable time scaling which reduces the time-varying systems to a set of constant-parameter systems.