Online ISSN
1350-911X
Print ISSN
0013-5194
Electronics Letters
Volume 21, Issue 5, 28 February 1985
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Volume 21, Issue 5
28 February 1985
Observation of second-harmonic generation from a Langmuir-Blodgett monolayer of a merocyanine dye
- Author(s): I.R. Girling ; N.A. Cade ; C.M. Montgomery
- Source: Electronics Letters, Volume 21, Issue 5, p. 169 –170
- DOI: 10.1049/el:19850119
- Type: Article
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Second-harmonic generation (SHG) from a merocyanine dye Langmuir-Blodgett monolayer is reported. Values for the second-order molecular polarisability β and its average orientation within the layer are deduced. Extinction of the SHG is observed for symmetrical bilayers. Protonation of a dye monolayer is seen to suppress SHG.
High-performance thin-film barretter mount for power measurement in W-band
- Author(s): T. Inoue ; I. Yokoshima ; M. Sasaki
- Source: Electronics Letters, Volume 21, Issue 5, p. 170 –172
- DOI: 10.1049/el:19850120
- Type: Article
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A high-performance barretter mount developed at 94 GHz in W-band is described, which has an effective efficiency of more than 99%. Both matching bandwidth and sensitivity are also satisfactory. The mount is useful for precise power measurement in W-band and the method of construction is applicable to high-performance barretter mounts in other millimetre bands.
Practical performance of a microwave distributed MESFET mixer
- Author(s): O.S.A. Tang and C.S. Aitchison
- Source: Electronics Letters, Volume 21, Issue 5, p. 172 –173
- DOI: 10.1049/el:19850121
- Type: Article
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The practical performance of a two-stage microwave distributed MESFET mixer is presented for the first time, based on the concept of distributed or travelling-wave mixing. A conversion loss of 4 dB (+1, −0.5 dB) was measured at fixed bias with a signal frequency varying from 2 to 10 GHz for an IF of 1.5 GHz and 6 dBm of LO pump power. This performance is believed to be superior to any currently available microwave mixer covering this wide bandwidth.
Active mode-locking of an InGaAsP 1.55 μm laser in a fibre resonator with an integrated single-mode-fibre output port
- Author(s): G. Eisenstein ; R.S. Tucker ; S.K. Korotky ; U. Koren ; J.J. Veselka ; L.W. Stulz ; R.M. Jopson ; K.L. Hall
- Source: Electronics Letters, Volume 21, Issue 5, p. 173 –175
- DOI: 10.1049/el:19850122
- Type: Article
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We describe the first 1.55 μm InGaAsP optical-fibre composite-cavity laser with an integrated single-mode-fibre output port. Mode-locked pulsewidths of 4.8 ps at a 2 GHz repetition rate, with peak powers of 56 mW, are demonstrated. These are the shortest reported mode-locked pulses from InGaAsP lasers.
Effectively nonreciprocal evanescent-wave optical-fibre directional coupler
- Author(s): M.S. Whalen and T.H. Wood
- Source: Electronics Letters, Volume 21, Issue 5, p. 175 –176
- DOI: 10.1049/el:19850123
- Type: Article
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An effectively nonreciprocal directional coupler has been demonstrated using evanescent coupling between a single-mode and a multimode optical fibre. At least 17 dB difference in coupling efficiency between transmit and receive branches has been measured. The near-field mode patterns show coupling between the single-mode fibre and a few high-order modes of the multimode fibre.
Scaling-free McClellan transform for 2-D digital filters
- Author(s): D.T. Nguyen and M.N.S. Swamy
- Source: Electronics Letters, Volume 21, Issue 5, p. 176 –178
- DOI: 10.1049/el:19850124
- Type: Article
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The original McClellan transformation used in the design of 2-dimensional digital filters having quadrantally symmetrical magnitude response, involves the substitution cos ω = F(cos ω1, cos ω2). For real frequencies, a scaling procedure was proposed by Mersereau et al. (1976) to guarantee that |F|≤1 using the two values Fmax and Fmin. In the letter, we first present extremely simple formulas for the scaling factors, then suggest a modified transform which not only is scaling-free but also contains one less coefficient than the original transform.
110 GHz GaAs FET oscillator
- Author(s): H.Q. Tserng and B. Kim
- Source: Electronics Letters, Volume 21, Issue 5, p. 178 –179
- DOI: 10.1049/el:19850125
- Type: Article
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A W-band GaAs FET oscillator has been demonstrated for the first time. A 75 μm gate width device with sub-half-micrometre (0.2 μm) electron-beam defined gates was used as a common-gate oscillator for operation in the 70 to 110 GHz frequency range. The highest oscillation frequency achieved was 110 GHz.
Mode selectivity in DFB lasers with cleaved facets
- Author(s): J. Buus
- Source: Electronics Letters, Volume 21, Issue 5, p. 179 –180
- DOI: 10.1049/el:19850126
- Type: Article
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The mode selectivity of distributed feedback lasers with cleaved facets is examined for various positions of the grating relative to the facets. The expected yield of single-mode lasers is calculated for several values of the coupling coefficient.
High-speed GaInAs Schottky photodetector
- Author(s): N. Emeis ; H. Schumacher ; H. Beneking
- Source: Electronics Letters, Volume 21, Issue 5, p. 180 –181
- DOI: 10.1049/el:19850127
- Type: Article
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A Schottky contact photodiode on p-type GaInAs for application at λ=1.3–1.6 μm has been fabricated and tested. The coaxial type device shows an external quantum efficiency of 19% at λ=1.27 μm, and rise and fall times of less than 15 ps.
Operation trial of 400 Mbit/s submarine optical transmission system
- Author(s): S. Tsutsumi ; I. Kitazawa ; H. Kimoto ; O. Kawata
- Source: Electronics Letters, Volume 21, Issue 5, p. 182 –183
- DOI: 10.1049/el:19850128
- Type: Article
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The letter reports the 8000 m deep-sea trial of a 400 Mbit/s submarine optical system, FS-400M, which was carried out in the Ogasawara trench in November 1984. Two repeaters fully integrated by six monolithic ICs, and 28 km-long submarine cables were used. In addition to transmission experiments for repeater spacing of 40 km, repair operation was simulated to confirm operational feasibility of the FS-400M.
Multiport optical fibre switch using a new hexagonal prism design
- Author(s): C.F. Buhrer
- Source: Electronics Letters, Volume 21, Issue 5, p. 183 –184
- DOI: 10.1049/el:19850129
- Type: Article
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The optical fibre switching function required to substitute one spare transmitter for any one of eight other active laser transmitters that may be failing is implemented in a single switching device using a new prism design that permits the exchange of optical signals between parallel beams.
New design of a dual-mode quartz crystal oscillator
- Author(s): M. Mourey and J.L. Vaterkowski
- Source: Electronics Letters, Volume 21, Issue 5, p. 184 –186
- DOI: 10.1049/el:19850130
- Type: Article
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A new method has been developed to drive a single quartz crystal in both of its modes. Using a modulator and a demodulator the oscillator provides a C mode frequency output directly as well as the difference frequency between the C and B modes. Results concerning this dual-mode oscillator used in a digital temperature compensated quartz crystal oscillator (DTCXO) are reported.
Phase accuracy and stability of quadrature IF demodulators
- Author(s): H.D. Griffiths ; N.R.W. Long ; J.G. Schoenenberger
- Source: Electronics Letters, Volume 21, Issue 5, p. 186 –187
- DOI: 10.1049/el:19850131
- Type: Article
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Baseband signal processing involves the provision of quadrature channels if phase information is of importance. A technique of producing extremely well matched quadrature phase detectors over a 40 dB dynamic range is described, together with a scheme to measure the resulting phase errors to an accuracy of less than 1 min.
Effects of dispersion in a 565 Mbit/s optical fibre laboratory system
- Author(s): D.S. Larner
- Source: Electronics Letters, Volume 21, Issue 5, p. 187 –189
- DOI: 10.1049/el:19850132
- Type: Article
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565 Mbit/s system tests are described, aimed at revealing the combined effects of pulse-broadening and mode-partition dispersion, which are of principal interest in system design. The tests make use of single-mode fibres with dispersion zeros at both 1300 and 1550 nm.
Linearity and efficiency improvement by active compensation in IMPATT amplifiers
- Author(s): A. Riris and C.S. Aitchison
- Source: Electronics Letters, Volume 21, Issue 5, p. 189 –190
- DOI: 10.1049/el:19850133
- Type: Article
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Active compensation is a successful microwave circuit technique previously developed to improve the gain-bandwidth performance of reflection amplifiers under small-signal conditions. The letter describes how this technique can be used to enhance the linearity of IMPATT amplifiers under large-signal conditions.
Intermodulation distortion improvement by active compensation in impatt amplifiers
- Author(s): A. Riris and C.S. Aitchison
- Source: Electronics Letters, Volume 21, Issue 5, p. 190 –191
- DOI: 10.1049/el:19850134
- Type: Article
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The letter discusses how the intermodulation distortion in impatt diode amplifiers can be improved significantly by active compensation. Theoretical evaluation based on a large-signal impatt diode model predicts considerable improvement in the intermodulation behaviour; in particular, the improvement in the third-order intercept point is found to be in excess of 12 dB.
Bit error rate evaluation of optical signals amplified via stimulated Raman process in an optical fibre
- Author(s): Y. Aoki ; S. Kishida ; K. Washio ; K. Minemura
- Source: Electronics Letters, Volume 21, Issue 5, p. 191 –193
- DOI: 10.1049/el:19850135
- Type: Article
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Gain-stabilised Raman amplification in a silica fibre has been realised by means of backward pumping with a continuously mode-locked Nd:YAG laser. This enabled the first bit error rate evaluation of Raman amplified laser diode light signals. The power penalty owing to gain fluctuation has been suppressed to about 1 dB even at a gain as high as 14 dB.
Polarisation-dependent gain-current relationship in InGaAs/InGaAlAs/InAlAs SCH-MQW laser diodes
- Author(s): K. Wakita ; Y. Kawamura ; H. Asahi
- Source: Electronics Letters, Volume 21, Issue 5, p. 193 –194
- DOI: 10.1049/el:19850136
- Type: Article
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The polarisation-dependent gain spectra were measured at −190 C for InGaAs InGaAlAs InAlAs SCH-MQW laser diodes. The peak gain for TE polarisation was much larger (>750 cm−1) than that for TM polarisation, while the peak gain difference for InGaAs InAlAs DH lasers was as small as 15 cm−1. This peak gain difference for SCH-MQW lasers is surprisingly larger than that for GaAs GaAlAs MQW lasers. This difference was explained by the polarisation-related selection rules for optical transition.
1.52 μm room-temperature photon-counting optical time domain reflectometer
- Author(s): B.F. Levine ; C.G. Bethea ; J.C. Campbell
- Source: Electronics Letters, Volume 21, Issue 5, p. 194 –196
- DOI: 10.1049/el:19850137
- Type: Article
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We demonstrate the first photon-counting optical time domain reflectometer which operates at room temperature and at a wavelength of 1.52 μm. A range of 50 km is achieved for the detection of an index-matched fibre end.
Experimental gain and noise figure performance of distributed MESFET amplifiers
- Author(s): N. Nazoa-Ruiz and C.S. Aitchison
- Source: Electronics Letters, Volume 21, Issue 5, p. 196 –197
- DOI: 10.1049/el:19850138
- Type: Article
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The noise figure and gain characteristics of lossless and lossy MESFET distributed amplifiers have been theoretically investigated by various workers. In the letter, in order to support previously reported theoretical results, the experimentally measured noise figure and power gain performance of two-stage and five-stage hybrid microwave distributed amplifiers employing MESFETs are presented. The measured results are compared to theoretically obtained values and found to be in reasonable agreement over most of the band.
Direct streak-camera observation of picosecond gain-switched optical pulses from a 1.5 μm semiconductor laser
- Author(s): I.H. White ; D.F.G. Gallagher ; M. Osiński ; D. Bowley
- Source: Electronics Letters, Volume 21, Issue 5, p. 197 –199
- DOI: 10.1049/el:19850139
- Type: Article
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For the first time a streak camera has been used to observe picosecond pulses generated at 1.5 μm wavelength by an injection laser without the use of frequency-doubling techniques in the detection system. Gain-switched pulses of 11 ps halfwidth have been observed, and hitherto unmeasured pulse delay data have been obtained. The observed pulse widths are believed to be the shortest yet generated using 1.5 μm diode lasers.
Novel bipolar differential input/output current-controlled current source
- Author(s): C. Toumazou and F.J. Lidgey
- Source: Electronics Letters, Volume 21, Issue 5, p. 199 –200
- DOI: 10.1049/el:19850140
- Type: Article
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A new bipolar differential input/output current-controlled current source (CCCS) is described. The basic cell consists of a translinear array of six transistors with two bipolar inputs, and is suited for the input stage of a differential current-mode operational amplifier.
Dependence of linewidth enhancement factor α on waveguide structure in semiconductor lasers
- Author(s): K. Furuya
- Source: Electronics Letters, Volume 21, Issue 5, p. 200 –201
- DOI: 10.1049/el:19850141
- Type: Article
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In semiconductor lasers, the ratio α of the real part to the imaginary part of the change in refractive index due to the change in carrier density determines the magnitude of dynamic and static line broadenings. The letter reports that the effective value of α depends on the structure of the waveguide, where both index and gain mechanisms induce transverse-mode guiding.
Design and fabrication of dispersion-shifted depressed-clad triangular-profile (DDT) single-mode fibre
- Author(s): H.-T. Shang ; T.A. Lenahan ; P.F. Glodis ; D. Kalish
- Source: Electronics Letters, Volume 21, Issue 5, p. 201 –203
- DOI: 10.1049/el:19850142
- Type: Article
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A new depressed-clad triangular-index-profile single-mode fibre with dispersion minimum shifted to the 1.55 μm region is investigated. Fibres with high cutoff wavelength (≃1.1 μm) and low dispersion slope (≃0.052 ps/km nm2) at their minimum dispersion wavelength (≃1.55 μm) were fabricated. Results from 226.7 km of fibre show an average loss of 0.241 dB/km at 1.55 μm and 0.232 dB/km at the loss minimum.
Reduction of sidelobe level by improved strut design for low F/D Cassegrain antennas
- Author(s): G. Shindler
- Source: Electronics Letters, Volume 21, Issue 5, p. 203 –204
- DOI: 10.1049/el:19850143
- Type: Article
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Different strut configurations have been experimentally tested on a 3 m Cassegrain antenna model in order to reduce the far-out sidelobes caused by strut radiation.
New automatic control of returned light into frequency stabilised semiconductor laser
- Author(s): S. Shinohara ; N. Inoue ; H. Yoshida ; M. Sumi
- Source: Electronics Letters, Volume 21, Issue 5, p. 205 –206
- DOI: 10.1049/el:19850144
- Type: Article
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A novel method of automatic phase control for returned light from an external mirror into a frequency stabilised semiconductor laser is proposed and demonstrated. It is based on the negative feedback of phase error signal obtained by weak intensity modulation of returned light to the position of the external mirror.
Hydroxyl production in optical fibres coated with hydrogen-free plastic materials
- Author(s): H. Itoh ; Y. Ohmori ; M. Nakahara
- Source: Electronics Letters, Volume 21, Issue 5, p. 206 –208
- DOI: 10.1049/el:19850145
- Type: Article
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Optical loss increase characteristics with heat treatment are investigated for two kinds of GeO2-doped silica fibres. The two fibres are coated with polypropylene (PP) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP), respectively. Loss increase due to OH ions occurs through heat treatment for the two kinds of fibres below 500°C, although the thermoplastic materials (PP and FEP) generate no hydrogen gas. It is concluded from the experiments that some origin of hydrogen exists in the fibre glass.
High-power and high-speed GaAlAs-GaAs LEDs fabricated by MOCVD growth
- Author(s): K. Nitta ; T. Komatsubara ; H. Kinoshita ; Y. Iizuka ; M. Nakamura ; T. Beppu
- Source: Electronics Letters, Volume 21, Issue 5, p. 208 –209
- DOI: 10.1049/el:19850146
- Type: Article
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GaAlAs light-emitting diodes fabricated by a metalorganic chemical vapour deposition method exhibit high-power and high-speed response characteristics at least as good as those made by liquid phase epitaxial growth. Maximum external quantum efficiency, standard graded index fibre input power and cutoff frequency at a forward current of 100 mA are 3.9%, 163 μW and 73 MHz. respectively.
Proposal to use reflected signals through a single Butler matrix to produce multiple beams from a circular array antenna
- Author(s): J.R.F. Guy
- Source: Electronics Letters, Volume 21, Issue 5, p. 209 –211
- DOI: 10.1049/el:19850147
- Type: Article
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The letter describes how a single Butler matrix network together with some circulators could be used in a reflective manner to produce multiple beams from a circular array antenna. An overall reduction in the number of signal processing components is achieved, compared to the conventional approach using two Butler matrices.
Effects of channel shapes on MOSFET hot-electron resistance
- Author(s): T.-Y. Huang
- Source: Electronics Letters, Volume 21, Issue 5, p. 211 –212
- DOI: 10.1049/el:19850148
- Type: Article
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Transistors with funnel-shaped channel regions are studied in terms of hot-electron effects. Experimental results indicate that funnel-shaped transistors are more resistant to hot-electron effects when operating with the wider-channel region close to the drain. It is suggested that future transistor design could take advantage of this effect in obtaining optimum hot-electron-resistant transistors.
Three-dimensional systolic architecture for beamforming
- Author(s): W. Marwood and A.P. Clarke
- Source: Electronics Letters, Volume 21, Issue 5, p. 212 –213
- DOI: 10.1049/el:19850149
- Type: Article
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A three-dimensional systolic architecture is described that efficiently performs passive broadband interpolation beam-forming for an array of sensors. The architecture transforms from time domain to beam space without intermediate data storage. The required convolution operations are implemented with linear sets of multiply/accumulate elements.
SNR comparison between two designs of PFM demodulator used to demodulate PFM or FM
- Author(s): D.J.T. Heatley
- Source: Electronics Letters, Volume 21, Issue 5, p. 214 –215
- DOI: 10.1049/el:19850150
- Type: Article
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PFM demodulation which relies on the generation of one pulse per PFM signal period is compared with demodulation which generates two pulses per period. The dual pulse approach is shown to give an SNR advantage of up to 7 dB for the same input conditions, but the two methods give SNRs which converge when used to demodulate FM.
Absolute-type pseudorandom shaft encoder with any desired resolution
- Author(s): E. Petriu
- Source: Electronics Letters, Volume 21, Issue 5, p. 215 –216
- DOI: 10.1049/el:19850151
- Type: Article
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It is shown how to use a 2n−1 length pseudorandom binary sequence to develop an absolute-type shaft encoder having any t resolution, where 2n−1−1<t<2n−1. The shaft encoder rotating device has only two concentric code-track and 2n−1 reading heads. A sequential code-conversion method is used to translate the pseudorandom patterns into natural binary code.
Erratum: Stray-insensitive differential input stages for A/D convertors
- Author(s): D.K. Shum and G.C. Temes
- Source: Electronics Letters, Volume 21, Issue 5, page: 216 –216
- DOI: 10.1049/el:19850152
- Type: Article
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