Showing papers in "Electronics Letters in 1989"
CNET1
TL;DR: In this paper, the luminescence of erbium implanted in various semiconductors such as Si, InP, GaAs, AlGaAs, GaInAsP, ZnTe and CdS is presented.
Abstract: Luminescence of erbium implanted in various semiconductors such as Si, InP, GaAs, AlGaAs, GaInAsP, ZnTe and CdS is presented. The Er/sup 3+/ emission wavelength is the same for all these semiconductors with a bandgap energy greater than the intrashell transition energy of Er 4f electrons (0.805 eV). The Er/sup 3+/ emission intensity depends strongly on both the bandgap energy of the host semiconductor and the material temperature. To obtain an intense room temperature emission, a wide-gap semiconductor must be used.
420 citations
TL;DR: In this article, the authors proposed an analogue signal filtering method based on current amplifiers derived from well-known voltage amplifier circuits, which operate at higher signal bandwidths, with greater linearity, and have larger dynamic range than their voltage-based counterparts.
Abstract: This letter proposes an entirely new method for performing analogue signal filtering. All circuits are based upon current amplifiers but derived from well-known voltage amplifier circuits. These circuits possess the same sensitivity properties as their voltage amplifier counterparts. However, it is expected that these circuits will operate at higher signal bandwidths, with greater linearity, and have larger dynamic range than their voltage-based circuit counterparts.
386 citations
TL;DR: Vertical-cavity electrically driven lasers with three GaInAs quantum wells and diameters of several μm exhibit room-temperature pulsed current thresholds as low as 1·3mA with 958 nm output wavelength as mentioned in this paper.
Abstract: Vertical-cavity electrically driven lasers with three GaInAs quantum wells and diameters of several μm exhibit roomtemperature pulsed current thresholds as low as 1·3mA with 958 nm output wavelength.
291 citations
TL;DR: In this paper, the input impedance of stacked cylindrical dielectric resonator antennas is investigated experimentally, and the bandwidth of 25% has been observed for a standing wave ratio better than 2.
Abstract: The input impedance of stacked cylindrical dielectric resonator antennas is investigated experimentally. The dielectric resonators are made of different materials. The bandwidth of 25% has been observed for a standing wave ratio better than 2.
253 citations
TL;DR: In this article, a periodically poled, planar waveguide in lithium niobate was used to generate 532 nm radiation at room temperature by continuous-wave frequency doubling with a conversion efficiency of 5% per Wcm2.
Abstract: A periodically poled, planar waveguide in lithium niobate was used to generate 532 nm radiation at room temperature by continuous-wave frequency-doubling with a conversion efficiency of 5% per Wcm2. Quasi-phase-matching allowed generation of the second harmonic using the d33 nonlinear coefficient.
249 citations
TL;DR: In this paper, a bandpass version of sigma-delta modulation is presented, with simulation results for second and fourth-order convertors operating at 8 MHz, and simulations demonstrate a resolution of 16 bits over an 8 kHz band centred at 1 MHz.
Abstract: A bandpass version of sigma-delta modulation is presented, with simulation results for second- and fourth-order convertors. For the fourth-order convertor operating at 8 MHz, simulations demonstrate a resolution of 16 bits over an 8 kHz band centred at 1 MHz. Applications may include analogue/digital conversion for AM radio, and digital/analogue conversion for narrowband RF systems.
237 citations
TL;DR: In this paper, the blue light at 410 nm was generated by continuous-wave frequency doubling in a periodically poled lithium niobate channel waveguide at room temperature, using the d/sub 33/nonlinear coefficient.
Abstract: Blue light at 410 nm was generated by continuous-wave frequency-doubling in a periodically poled lithium niobate channel waveguide at room temperature. Quasi-phasematching allowed generation of the blue light using the d/sub 33/ nonlinear coefficient. >
229 citations
TL;DR: In this paper, it was demonstrated that stimulated Brillouin scattering (SBS) occurring in the core of an optical fiber can be used in the construction of a distributed temperature sensor.
Abstract: It is demonstrated that stimulated Brillouin scattering (SBS) occurring in the core of an optical fibre may be used in the construction of a distributed temperature sensor. Initial experiments with a length of fibre have shown that the sensitivity of the Stokes frequency to temperature is approximately 5.5 MHz/ degrees C and that different Stokes frequencies may be observed according to the temperature distribution along the fibre.<
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218 citations
TL;DR: In this paper, a single-quantum-well, surface-emitting microlaser with room-temperature continuous and pulsed lasing of vertical-cavity, surface emitting microlasers is achieved at ~983nm.
Abstract: Room-temperature continuous and pulsed lasing of vertical-cavity, single-quantum-well, surface-emitting microlasers is achieved at ~983nm. The active Ga[sub][0-8]In[sub][0-2]As single quantum well is 100 [angstroms] thick. These microlasers have the smallest gain medium volumes among lasers ever built. The entire laser structure is grown by molecular beam epitaxy and the microlasers are formed by chemically assisted ion-beam etching. The microlasers are 3-50-μm across. The minimum threshold currents are 1.1 mA (pulsed) and 1.5 mA (CW).
194 citations
TL;DR: In this article, a fundamental limit on the number of channels in an SCM lightwave CATV system was derived by considering an idealised link consisting of a shot-noise-limited receiver and a laser transmitter with a linear light/current characteristic.
Abstract: A fundamental limit on the number of channels in an SCM lightwave CATV system is derived by considering an idealised link consisting of a shot-noise-limited receiver and a laser transmitter with a linear light/current characteristic. For VSB-AM TV, the limit is only 50 channels per milliwatt of received optical power.
183 citations
Abstract: This paper provides a self-healing strategy to deal with catastrophic events when power system vulnerability analysis indicates that the system is approaching an extreme emergency state. The system is adaptively divided into smaller islands with consideration of quick restoration. Then an adaptive load shedding scheme based on the rate of frequency decline is applied. The proposed scheme is tested on a 179-bus, 20-generator sample system and shows very good performance.
TL;DR: In this paper, the authors investigated the impact of wind farm integration into utilities' network on critical clearing time (CCT) of the wind power based embedded generators (WPBEGs).
Abstract: Generation of electricity using wind power has received considerable attention worldwide in recent years. In order to investigate the impacts of the integration of wind farm into utilities' network various windmill models have been developed. One such impact is related to the critical clearing time (CCT) of the wind power based embedded generators (WPBEG). The work in this paper has shown that oversimplification of the modeling of windmill mechanical drive train could introduce significant error in the value of the CCT that defines the stability limit of an integrated wind farm. This paper also reports investigation into the factors that influence the dynamic behavior of the WPBEGs following network fault conditions. It is shown that wind farm CCT can be affected by various factors contributed by the host network. Results obtained from several case studies are presented and discussed. This investigation is conducted on a simulated grid-connected wind farm using EMTP.
TL;DR: In this article, the quantum-barrier-varactor diode (QBV diode) was proposed for use in multipliers for millimetre waves, where the capacitance/voltage characteristic is symmetric and only odd harmonics are obtained.
Abstract: A new device, the quantum-barrier-varactor diode (QBV diode), is proposed for use in multipliers for millimetre waves. Since the capacitance/voltage characteristic is symmetric, only odd harmonics are obtained. Hence there is no idler circuit to consider for the tripler and only one for the quintupler. It is shown that for triplers and quintuplers, the theoretical efficiency using QBVs is comparable or possibly larger than using Schottky varactor diodes.
TL;DR: In this paper, a single-proton avalanche diode (SPAD) with double-epitaxial silicon structure is presented, which has a short diffusion tail (270 ps time-constant), high resolution (45 ps FWHM, full width at half maximum of the peak) and low noise, i.e. low-dark-count rate.
Abstract: A new single-proton avalanche diode (SPAD) with double-epitaxial silicon structure is presented. The device has a time response with short diffusion tail (270 ps time-constant), high resolution (45 ps FWHM, full-width at half maximum of the peak) and low noise, i.e. low-dark-count rate.
TL;DR: In this paper, a high contrast (> 100:1) low-voltage multiple quantum well reflection modulator was demonstrated. But the performance was not as good as that achieved by using resonantly enhanced electroabsorption in GaAs quantum wells embedded in the spacer region of an asymmetric Fabry-Perot cavity.
Abstract: We report the demonstration of a high-contrast (> 100:1), low-voltage multiple quantum well reflection modulator. The performance is achieved by using resonantly-enhanced electroabsorption in GaAs quantum wells embedded in the spacer region of an asymmetric Fabry-Perot cavity, which is at the same time a pin diode. Optimum contrast is observed at ≃860nm with only 9 V bias and ≈3.5dB insertion loss.
TL;DR: By choosing pump wavelengths at which excited state absorption does not occur, efficient high gain operation of erbium-doped fiber amplifiers is possible as mentioned in this paper. But this is not the case for all pump wavelengths.
Abstract: By choosing pump wavelengths at which excited state absorption does not occur, efficient high gain operation of erbium-doped fibre amplifiers is possible. Practical pump wavelengths of 532nm and 980nm are identified as optimal, giving gains as high as 1.35 dB/mW and 2.2 dB/mW of pump at the two wavelengths, respectively.
TL;DR: In this article, offset phase-locking of two Nd:YAG nonplanar ring laser by electronic feedback was reported, and the difference frequency was continuously tunable in three bands from 6 to 34 GHz and exhibits a hold-in range and linewidth of 82 MHz and < 1 mHz, respectively.
Abstract: We report offset phase-locking of two Nd:YAG nonplanar ring lasers by electronic feedback. The difference frequency is continuously tunable in three bands from 6 to 34 GHz and exhibits a hold-in range and linewidth of 82 MHz and <1 mHz, respectively.
CNET1
TL;DR: In this article, the tunable CW operation of a thulium-doped fluorozirconate fiber laser around 0.82 μm, 1.48 μm and 2.35 μm is reported.
Abstract: Tunable CW operation of a thulium-doped fluorozirconate fibre laser around 0.82 μm, 1.48 μm, 1.88 μm and 2.35 μm is reported. The fibre is single mode above 1.7 μm. Laser dynamics and competition or collaboration between these wavelengths are examined.
TL;DR: In this article, active mode locking in a monolithic long-cavity semiconductor laser, operating at 1.5 µm wavelength, was reported. And the highest repetition rate achieved with an actively mode-locked laser was achieved with a modulation depth of 97%.
Abstract: We report active mode locking in a monolithic long-cavity semiconductor laser, operating at 1.5 µm wavelength. Pulses with durations of 4 ps at repetition rates up to 40 GHz have been achieved, with a modulation depth of 97%. This is the first report of active mode locking in a monolithic device, and the highest repetition rate achieved with an actively mode locked laser.
TL;DR: In this article, it was shown that a significant increase in temperature occurs in the channel of SOI transistors due to the relatively poor thermal conductivity of the buried insulator.
Abstract: From a two-dimensional solution of Laplace's equation it is shown that a significant increase in temperature occurs in the channel of SOI transistors due to the relatively poor thermal conductivity of the buried insulator. Based on this simulation an equation is derived which predicts that at small channel lengths the pinchoft point is shifted, an effect which is consistent with experimental observations. In addition, the positive 'kink' is reduced with increasing gate voltage and this effect, together with the negative differential resistance, can be explained by a temperature increase in the channel.
TL;DR: In this article, the authors reported the first experimental evidence of second harmonic generation due to inter-subband transitions in compositionally asymmetrical multiquantum wells using a continuous CO2 laser.
Abstract: We report the first experimental evidence of second harmonic generation due to inter-subband transitions in compositionally asymmetrical multiquantum wells using a continuous CO2 laser. The extremely large value of the second-order susceptibility (χ(2)2ω ~ 7.6×10−7m/V) is ingood agreement with theoretical predictions.
TL;DR: This paper analyzes the uncertainties involved in a cascaded neural network structure for MCP prediction and develops the prediction distribution under the Bayesian framework, which is computationally efficient and provides accurate prediction and confidence coverage.
Abstract: The deregulated power market is an auction market, and energy market clearing prices (MCP) are volatile. Good MCP prediction and its confidence interval estimation will help utilities and independent power producers submit effective bids with low risks. MCP prediction, however, is difficult since bidding strategies used by participants are complicated and various uncertainties interact in an intricate way. Furthermore, MCP predictors usually have a cascaded structure, as several key input factors need to be estimated first. Cascaded structures are widely used, however, they have not been adequately investigated. This paper analyzes the uncertainties involved in a cascaded neural network structure for MCP prediction and develops the prediction distribution under the Bayesian framework. A fast algorithm to evaluate the confidence intervals by using the memoryless quasi-Newton method is also developed. Testing results on a classroom problem and on New England MCP prediction show that the method is computationally efficient and provides accurate prediction and confidence coverage. The scheme is generic, and can be applied to various networks, such as multilayer perceptrons and radial basis function networks.
TL;DR: In this article, the authors propose fault-remedial control strategies for failures occurring in the drive voltage inverter, which may extend their use to applications where high reliability, also in the flux-weakening region, is a key-feature.
Abstract: Interior permanent magnet (IPM) synchronous motors are used extensively in many industrial drives, and the development of fault-tolerant control techniques may extend their use to applications where high reliability, also in the flux-weakening region, is a key-feature. This paper proposes some innovative fault-remedial control strategies for failures occurring in the drive voltage inverter.
TL;DR: In this article, the performance of a hybrid LP-MOVPE/LPE with a strained-layer active region was demonstrated for the first time, achieving a CW threshold current of 10 mA, differential quantum efficiency of 82%, T0 of 97 K and maximum output powers/facet as high as 70 mW CW and 180 mW for pulsed operation.
Abstract: Buried heterostructure Ga0.2In0.8As strained-layer (strain 1.8%) separate confinement, multiple quantum well laser diodes emitting at 1.5 μm were fabricated by hybrid LP-MOVPE/LPE. Improved performance as a result of the application of a strained-layer active region is demonstrated for the first time. A CW threshold current of 10 mA, differential quantum efficiency of 82%, T0 of 97 K and maximum output powers/facet as high as 70 mW CW and 180 mW for pulsed operation were measured. Lifetests at 60°C heat-sink temperature and 5 mW output power show almost no degradation after 2000 h.
TL;DR: In this article, a differential transconductance element based on CMOS inverters is presented, which is a linear, tunable integrator for very high-frequency continuous-time integrated filters.
Abstract: A differential transconductance element based on CMOS inverters is presented. With this circuit a linear, tunable integrator for very high-frequency continuous-time integrated filters can be made. This integrator has good linearity properties (THD<0.04%, Vipp=1.8 V), nondominant poles in the gigahertz range and a 40 dB DC gain
TL;DR: In this paper, an original analysis of a slot-coupled microstrip antenna is presented based on the transmission line model using previous expressions of conductance and susceptance due to the fringing fields near the edges of the patch; moreover, a simple interpretation of different impedance transformations is given.
Abstract: The letter presents an original analysis of a slot-coupled microstrip antenna. The transmission line model uses previous expressions of conductance and susceptance due to the fringing fields near the edges of the patch; moreover, a simple interpretation of the different impedance transformations is given. Resullts based on the transmission line model are compared with other theoretical analyses (cavity model, moment method) and measurements.
TL;DR: In this paper, a wideband and low-driving voltage Ti:LiNbO3 Mach-Zehnder optical modulator of nearly 50 Ω characteristic impedance has been developed employing a shielded phase-velocity-matching travelling-wave (TW) electrode.
Abstract: A wideband and low-driving voltage Ti:LiNbO3 Mach-Zehnder optical modulator of nearly 50 Ω characteristic impedance has been developed employing a shielded-phasevelocity-matching travelling-wave (TW) electrode. Both wide modulation bandwidth of 20 GHz (3 dB optical) and low driving voltage of 4.7 V were attained at 1.52 μm wavelength.
TL;DR: In this paper, the first integrated heterodyne receiver capable of real-time data reception with error-free reception of FSK-modulated pseudorandom digital code at 105 Mbit/s was presented.
Abstract: We describe the fabrication and performance of the first integrated heterodyne receiver capable of actual heterodyne data reception. Integrating a continuously tunable 1.5 μm MQW-DBR laser with a single-mode directional coupler/switch and zero-bias MQW waveguide photodetectors, we have achieved error-free reception of FSK-modulated pseudorandom digital code at 105 Mbit/s.
TL;DR: In this article, a modified signed-digit (MSD) representation of the exponent is proposed to speed up integer exponentiation by using a modified MSD representation of exponent and the method works best when the weight of the representation is minimized.
Abstract: A method for speeding up integer exponentiation by using a modified signed-digit (MSD) representation of the exponent is described. The method works best when the weight of the representation is minimised. An algorithm for finding a minimum weight MSD representation is presented.
TL;DR: In this article, a 1.5μm-range λ/4-shifted DFB laser with a l.2 mm-longcavity and three electrodes has been fabricated.
Abstract: A 1.5μm-range λ/4-shifted DFB laser with a l.2 mm-longcavity and three electrodes has been fabricated. The lasing wavelength can be tuned electrically over a 1.9 nm range, maintaining the linewidth below 900 kHz and a constant output power of 20 mW. The minimum linewidth of 500 kHz is achieved by nonuniform current injection.