Showing papers in "Electronics Letters in 1981"
TL;DR: In this article, a form of compound distribution is proposed to describe the non-Rayleigh distribution and correlation properties of high-resolution radar sea clutter and a possible physical mechanism is discussed.
Abstract: A proposed form of compound distribution to describe the non-Rayleigh distribution and correlation properties of high resolution radar sea clutter is shown to be a good fit to experimental data. From this model the K distribution is derived, and a possible physical mechanism is discussed.
401 citations
TL;DR: By using a superluminescent diode as the light source and a depolariser inside the fiber coil, a constant scale factor was achieved without using polarisation control elements.
Abstract: By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained.
228 citations
TL;DR: In this paper, the intrinsic losses are predicted to be 1 × 10?3 dB/km at 3.4?m for BaF2-GdF3-ZrF4 glass fibre, 1 × 9?2 dB/ km at 2.7?m and 1 × 6.5 dB/m for GeS3 glass fibre.
Abstract: Loss minima in two fluoride glass and chalcogenide glass fibres were calculated. The intrinsic losses are predicted to be 1 × 10?3 dB/km at 3.4 ?m for BaF2-GdF3-ZrF4 glass fibre, 1 × 10?2 dB/km at 2.7 ?m for BaF2-CaF2-YF3-AlF3 glass fibre and 1 × 10?2 dB/km at 4.5 ?m for GeS3 glass fibre.
207 citations
TL;DR: In this paper, a closed form expression for the equivalent line length associated with the single microstrip open end is presented for the use in microwave CAD programs, and the maximum relative error involved is less than 2.5% and its effect can be shown to be below physical tolerances.
Abstract: A closed form expression for the equivalent line length associated with the single microstrip open end is presented for the use in microwave CAD programs. The maximum relative error involved is less than 2.5% and its effect can be shown to be below physical tolerances.
204 citations
TL;DR: In this paper, low-loss and highly birefringent single polarisation fibres have been fabricated and the minimum transmission loss and the modal bire fringence of the fibre with refractive index difference was 0.61% and 0.62 dB/km at?=1.52?m and 8.5×10?5 at? =1.15?m, respectively.
Abstract: Low-loss and highly birefringent single polarisation fibres have been fabricated. The minimum transmission loss and the modal birefringence of the fibre with refractive-index difference ?=0.61% was 0.62 dB/km at ?=1.52 ?m and 8.5×10?5 at ?=1.15 ?m, respectively. The state of linear polarisation was stable against the handling conditions such as bending, twists, concentrated force, and temperature variations.
190 citations
TL;DR: The results of calculations and measurements on the SAW properties of a new piezoelectric material, lithium tetraborate (Li2B4O7), are reported in this paper.
Abstract: The results of calculations and measurements on the SAW properties of a new piezoelectric material, lithium tetraborate (Li2B4O7), are reported. A new temperature-compensated SAW device orientation has been located with a SAW velocity of 3510 ms−1 and a SAW coupling factor of 1.2×10−2. The properties of this cut are compared with those of several other SAW substrates.
146 citations
TL;DR: In this article, a coplanar waveguide on a semi-insulating GaAs substrate is described, which uses a cross-tie periodic structure consisting of lossless media.
Abstract: A new slow-wave coplanar waveguide on a semi-insulating GaAs substrate is described. The waveguide utilises a novel `cross-tie? periodic structure, consisting of lossless media. A simple analysis and experiments show linear dispersion with 10 to 40 times reduction of wavelength. The line appears useful for miniaturisation of distributed circuits in GaAs monolithic microwave integrated circuits.
134 citations
TL;DR: In this paper, a low-loss single-mode fibres that maintain polarisation well have been fabricated by the standard MCVD method, achieving an extinction ratio of less than −30 dB at 1 km and a loss of 0.8 dB/km at 1.5 μm.
Abstract: Low-loss single-mode fibres that maintain polarisation well have been fabricated by the standard MCVD method. An extinction ratio of less than −30 dB at 1 km and a loss of 0.8 dB/km at 1.5 μm were achieved by the concentric circular germanosilicate core-clad fibres with the borosilicate elliptical jacket.
123 citations
TL;DR: In this paper, a white-light interferometric technique was used to determine the dispersion of a short (~1 m) single-mode optical fiber using a Mach-Zehnder interferometer.
Abstract: Chromatic dispersion near 08 ?m in a short (~1 m) single-mode optical fibre is determined by a white-light interferometric technique In particular, the wavelength-dependent group delay of the fibre is obtained directly from the spectra of the output light from a Mach-Zehnder interferometer illuminated by a GaAlAs LED Its application in single-mode fibre studies in the 13 ?m wavelength region is discussed
121 citations
TL;DR: In this article, simple rings on close packed square or triangular lattices are useful frequency selective surfaces for reflector antennas, achieving a reflection bandwidth of about 26 per cent and transmission/reflection band ratio of 3:1 for angles of incidence up to 45° at least.
Abstract: Arrays of simple rings on close packed square or triangular lattices are useful frequency selective surfaces for reflector antennas. Reflection bandwidths of about 26 per cent and transmission/reflection band ratios of 3:1 are readily attainable for angles of incidence of up to 45° at least. Experimental transmission coefficients are compared with the results of modal computations.
116 citations
TL;DR: In this paper, the Lorentzian lineshape of a single longitudinal mode AlGaAs semiconductor laser is directly observed by optical heterodyne detection and a remarkable reduction in the spectral linewidth to less than 50 kHz is achieved with external grating feedback.
Abstract: The Lorentzian lineshape of a single longitudinal mode AlGaAs semiconductor laser is directly observed by optical heterodyne detection. A remarkable reduction in the spectral linewidth to less than 50 kHz is achieved with external grating feedback. The experimental linewidth is in reasonable agreement with the theoretical value, which is obtained by finesse calculation of the active Fabry-Perot cavity.
TL;DR: In this paper, the authors compared several methods for generating stable reduced order models with an old and very simple method of reduction based on the truncation of the high order system transfer function.
Abstract: Recently published methods for generating stable reduced order models are compared with an old and very simple method of reduction based on the truncation of the high order system transfer function. Numerical examples show the truncation method, which requires no computation, to be as good as the other methods.
TL;DR: In this article, a GaInAsP/InP laser transmitter module incorporating an external cavity is described and it is shown that the cavity produces stable tunable single longitudinal mode operation of the laser even under high speed modulation conditions.
Abstract: A GaInAsP/InP laser transmitter module incorporating an external cavity is described. It is shown that the cavity produces stable tunable single longitudinal mode operation of the laser even under high speed modulation conditions.
TL;DR: In this article, a modulated laser beam, incident on a surface, gives rise to a time-varying surface displacement, which can be detected by means of a laser interferometer, thereby forming the basis for a novel imaging system.
Abstract: A modulated laser beam, incident on a surface, gives rise to a time-varying surface displacement. This displacement can be detected by means of a laser interferometer, thereby forming the basis for a novel imaging system. Preliminary results to demonstrate the viability of such a technique are presented.
TL;DR: In this article, a theory for planar metal antennas on a dielectric surface has been developed, and the main predictions have been verified experimentally, and they have been shown to have radiation diagrams and impedances favorable for microwave to far-infra-red integrated circuits.
Abstract: A theory has been developed for planar metal antennas on a dielectric surface and the main predictions have been verified experimentally. Current dipole antennas have radiation diagrams and impedances favourable for microwave to far-infra-red integrated circuits.
TL;DR: In this article, a thickness-extensional mode piezoelectric resonator consisting of a ZnO/SiO2 diaphragm supported by a silicon wafer was presented.
Abstract: We report on a thickness-extensional-mode piezoelectric resonator consisting of a ZnO/SiO2 diaphragm supported by a silicon wafer. It is found that the temperature coefficient of frequency can be reduced to zero by adjusting the ZnO/SiO2 thickness ratio. A temperature coefficient of frequency as low as 10 ppm/°C was experimentally obtained.
TL;DR: In this article, Bistability of InP/InGaAsp/InP DH with a periodic excitation stripe geometry is reported. But their performance depends on the stripe geometry and heat sink temperature, and they are controllable.
Abstract: Bistable operation in InP/InGaAsP/InP DH lasers with a periodic excitation stripe geometry is reported. Bistability is observed within a current range of about 10% of the threshold current for maximum value. The range strongly depends on the stripe geometry and heat sink temperature, and they are controllable.
TL;DR: In this article, a V-grooved substrate buried-heterostructure laser emitting at 1.3?m wavelength is described and the active layer is buried in the V-shaped groove.
Abstract: A V-grooved substrate buried-heterostructure laser emitting at 1.3 ?m wavelength is described. The active layer is buried in the V-shaped groove. A CW threshold current of 10~20 mA is obtained and a far-field pattern free from irregularity and peak shift is realised. Damped relaxation oscillation and stable aging characteristics are obtained.
TL;DR: In this paper, a band center frequency ratio of 1/1.3 is given by an array of compound elements with two concentric rings, and the transmission curves are more complex than those for simple rings, but provide more closely spaced reflection and transmission bands.
Abstract: Concentric rings can be used as array elements in frequency selective surfaces. The transmission curves are more complex than those for simple rings, but provide more closely spaced reflection and transmission bands. In an example discussed here, a band centre frequency ratio of 1/1.3 is given by an array of compound elements with two concentric rings.
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TL;DR: In this paper, a scheme for the tuning of filters is proposed, where filters are time-shared between a signal path and a tuning path, so that each filter in a system is individually tuned.
Abstract: A scheme for the tuning of filters is proposed. In it, filters are time-shared between a signal path and a tuning path, so that each filter in a system is individually tuned. An accurate system frequency response can thus be achieved which does not rely on tight matching between filters.
TL;DR: In this article, a DC threshold of about 250 mA at 25°C and a temperature coefficient of the lasing wavelength of 1.57 μm was obtained for room temperature CW operation of distributed-feedback buried-heterostructure InGaAsP/InP lasers emitting at 1.0 A/°C.
Abstract: Room temperature CW operation of distributed-feedback buried-heterostructure InGaAsP/InP lasers emitting at 1.57 μm was achieved. A DC threshold of about 250 mA at 25°C and a temperature coefficient of the lasing wavelength of 1.0 A/°C were obtained. Some of these lasers manifested single longitudinal mode operation both in DC condition and in deeply modulated condition at 500 Mbit/s.
TL;DR: In this article, it was shown that spinning the preform during drawing produces a fibre with a permanent twist and negligible polarisation birefringence and rotation, and that polarisation mode dispersion is similarly reduced.
Abstract: Spinning the preform during drawing produces a fibre with a permanent twist. It is shown that such a fibre has negligible polarisation birefringence and rotation. Polarisation mode dispersion is similarly reduced.
TL;DR: In this paper, the authors measured the refractive index versus wavelength of several compositions of GaInAsP grown by vapour phase epitaxy on InP. The self-consistent data showed reasonable agreement with existing theories for wavelengths larger than the absorption edge.
Abstract: We have measured the refractive index versus wavelength of several compositions of GaInAsP grown by vapour phase epitaxy on InP. The self-consistent data show reasonable agreement with existing theories for wavelengths larger than the absorption edge. However, at and below the band edge, detail is measured that is not predicted by the simple theories.
TL;DR: In this paper, a technique for measuring equivalent-step-index profiles of monomode fibres is presented which involves measuring the mode spot size directly as a function of wavelength, and compares favourably with measured profiles.
Abstract: A new technique for measuring equivalent-step-index profiles of monomode fibres is presented which involves measuring the mode spot-size directly as a function of wavelength, and compares favourably with measured profiles. Since characterisation of the fibre is derived from easily measured optical properties, knowledge of the actual profile and the modelling of the propagation characteristics from it is unnecessary.
TL;DR: In this article, a longwavelength back-illuminated PIN photodiodes capable of detecting optical signals at multigigabit modulation rates have been fabricated and tested in a stripline circuit.
Abstract: Long-wavelength back-illuminated PIN photodiodes capable of detecting optical signals at multigigabit modulation rates have been fabricated and tested in a stripline circuit. A transit-time-limited response time of about 30 ps has been realised in a 25 μm-diameter diode.
TL;DR: In this paper, a GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BJB-DBR integrated laser for short) is proposed and demonstrated.
Abstract: A novel GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BJB-DBR integrated laser for short) is proposed and demonstrated. In this structure, it is found theoretically that an efficient coupling of 98% between the active and butt-jointed external waveguides is available by matching the propagation constants and the field profiles of both waveguides, which gives relatively larger fabrication tolerance. Prototype BJB-DBR integrated lasers with emitting wavelength of 1.55 µm were fabricated, and single-longitudinal-mode operation was obtained at room temperature.
TL;DR: In this article, the authors report two circuits simulating ideal floating inductances and a capacitor floatation scheme using grounded copacitors. Both the inductance and capacitors are tunable through a single resistance and it is possible to simulate these realisations with unmatched passive components.
Abstract: The letter reports two circuits simulating ideal floating inductances and a capacitor floatation scheme using grounded copacitors. Both the inductances and capacitors are tunable through a single resistance and it has been shown that it is possible to simulate these realisations with unmatched passive components.
TL;DR: The letter presents a new ideal floating inductance using second generation current conveyors (CCIIs) that is realisation with all grounded passive components.
Abstract: The letter presents a new ideal floating inductance using second generation current conveyors (CCIIs). The novel feature of this scheme is its realisation with all grounded passive components.
TL;DR: In this article, a useful design expression for normalised power transmission in single mode optical branching waveguides was obtained, where the power transmission was determined only by the normalised waveguide thickness and normalised branching angle.
Abstract: A useful design expression for normalised power transmission in single mode optical branching waveguides has been obtained, where the power transmission is determined only by the normalised waveguide thickness and normalised branching angle. The effect of blunting of the wedge tip of the branching is also investigated.
TL;DR: A novel CCII-based circuit using a single grounded capacitor for single-resistance-controlled lossless floating inductance simulation is presented.
Abstract: A novel CCII-based circuit using a single grounded capacitor for single-resistance-controlled lossless floating inductance simulation is presented.