Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 24, Issue 4
Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 4, 18 February 1988

Volumes & issues:

Volume 24, Issue 4

18 February 1988

Interferometric optical fibre sensors using internal mirrors
Optimisation of signal/clutter ratio using polarisation diversity
Optimum design of FIR switched-capacitor decimators using low-gain amplifiers
Linewidth of monolithic external cavity DFB lasers
Analysis of Hg1−xCdxSe alloys in electroreflectance
150 Mbit/s phase diversity ASK homodyne receiver with a linewidth/bit rate ratio of 0.5
Adaptive image restoration of sigma filter using local statistics and human visual characteristics
  • Author(s): S.-H. Jung  and  N.-C. Kim
  • Source: Electronics Letters, Volume 24, Issue 4, p. 201 –202
  • DOI:  10.1049/el:19880134
  • Type: Article
  • + Show details - Hide details
  • p. 201 –202 (2)
    The sigma filter is a nonlinear scheme for modifying an average (mean) filter to improve its edge-preserving characteristic. However, this filter is susceptible to impulsive noise, such as BSC (binary symmetric channel) noise. In this letter, a simple adaptive algorithm for a sigma filter is presented using local image statistics and human visual characteristics to compensate for its drawbacks. Experimental results for an image degraded by BSC noise show that the proposed algorithm has much better performance than nonadaptive ones both on SNR gain and on subjective image quality.
    Add to favourites
    Export citations
Spike-free biphase switched-capacitor integrator pair with low sensitivity to nonideal op-amp effects
Correlation between anomalous latch-up I/V characteristics and observation of current distribution by IR microscopy in CMOS ICs
High-resolution ultrasound transverse flow measurement
Correction to effective index method for rectangular dielectric waveguides
Effects of Nakagami fading on antijam performance requirements
  • Author(s): E.K. Al-Hussaini
  • Source: Electronics Letters, Volume 24, Issue 4, p. 208 –209
  • DOI:  10.1049/el:19880139
  • Type: Article
  • + Show details - Hide details
  • p. 208 –209 (2)
    The effect of fading on antijam (AJ) performance is considered when the envelopes of both the desired signal and the jamming signal fade with a Nakagami distribution. Two cases are analysed for conventional systems. In the first case, the fading is assumed to be slow compared with the duration of the message. In the second case, the fading is assumed to be slow compared with the symbol duration but fast compared with the message duration. For both cases numerical results are also included.
    Add to favourites
    Export citations
Efficient calculation of interconnection delays on GaAs-based VHSIC
Wideband guided-wave periodic multi/demultiplexer with a ring cavity for optical FDM transmission systems
Online fruit weighing using a 500 MHz waveguide cavity
7× electrical pulse compression an inhomogeneous nonlinear transmission line
  • Author(s): M. Tan ; C.-Y. Su ; W.J. Anklam
  • Source: Electronics Letters, Volume 24, Issue 4, p. 213 –215
  • DOI:  10.1049/el:19880143
  • Type: Article
  • + Show details - Hide details
  • p. 213 –215 (3)
    A device which directly compresses electrical pulses using the concepts of soliton propagation along an inhomogeneous nonlinear transmission line is described. Numerical simulations on SPICE indicate that a 5 V input pulse with a FWHM of 66 ps can be compressed to a ≥10 V output pulse with a FWHM ≤5 ps. A compression factor of ≥7 has been experimentally measured on a low frequency scale model compressor.
    Add to favourites
    Export citations
Least-squares determination of the inversion of Laplace transforms via Taylor series
  • Author(s): M. Razzaghi  and  M. Razzaghi
  • Source: Electronics Letters, Volume 24, Issue 4, p. 215 –216
  • DOI:  10.1049/el:19880144
  • Type: Article
  • + Show details - Hide details
  • p. 215 –216 (2)
    Since the numerical inversion of Laplace transforms using Taylor series causes numerical instability owing to inversion of the Hilbert matrix, Unnikrishnan and Mathew recently proposed a technique to avoid the inversion of this ill-conditioned matrix. In the letter we show that improper use of their method could lead to very unreliable results. An implementation of their algorithm based on weighted least squares is also suggested.
    Add to favourites
    Export citations
All-optical active switch using a multiple quantum well nonlinear etalon as a laser diode mirror
1.5 μm InP/GaInAsP linear laser array with twelve individually addressable elements
  • Author(s): L.A. Koszi ; B.P. Segner ; H. Temkin ; W.C. Dautremont-Smith ; D.T.C. Huo
  • Source: Electronics Letters, Volume 24, Issue 4, p. 217 –219
  • DOI:  10.1049/el:19880146
  • Type: Article
  • + Show details - Hide details
  • p. 217 –219 (3)
    Linear arrays of twelve individually addressable InP/GaInAsP channelled-substrate buried-heterostructure lasers emitting at λ = 1.5 μm were fabricated. Spacing between active elements (250 μm) was made to match the fibre spacing in a 12-fibre ribbon. Individual arrays were epoxy bonded, p-side up to metallised BeO carriers. Best case uniformity of laser characteristics within an array is indicated by tight distributions of lasing threshold (9.8 ± 0.9 mA at 30°C) and output powers of (8.6 ± 0.4 mW at 100 mA). While no significant optical crosstalk could be detected, small increases (⋍ 10%) in device lasing thresholds were observed when two adjacent elements were operated CW simultaneously, probably due to the thermal impedance of the epoxy-bond employed and the resultant heating of operating nearest-neighbour devices. Such arrays offer the potential for reduced fibre alignment time per element thus reducing packaging costs per source. In addition, reduced space requirement per source is realised.
    Add to favourites
    Export citations
Low-dispersion fluoride glass single-mode fibres operating in two spectral ranges
  • Author(s): Y. Ohishi  and  S. Takahashi
  • Source: Electronics Letters, Volume 24, Issue 4, p. 220 –221
  • DOI:  10.1049/el:19880147
  • Type: Article
  • + Show details - Hide details
  • p. 220 –221 (2)
    Chromatic dispersion characteristics of fluoride glass singlemode fibres are investigated experimentally and theoretically. It is proposed that the quasi-single-mode operation at zero material dispersion wavelength is effective in extending the low dispersive spectral range. It is shown that total chromatic dispersion is suppressed within ± 1 ps/km/nm in the two spectral ranges of 1.57–1.71 μm and 2.4–3.35 μm.
    Add to favourites
    Export citations
Electro-optical modulators using novel buried waveguides in GaInAsP/InP material
  • Author(s): Y. Bourbin ; A. Enard ; R. Blondeau ; M. Razeghi ; D. Rondi ; M. Papuchon ; B. de Cremoux
  • Source: Electronics Letters, Volume 24, Issue 4, p. 221 –223
  • DOI:  10.1049/el:19880148
  • Type: Article
  • + Show details - Hide details
  • p. 221 –223 (3)
    Losses as low as 0.4 ± 0.2 dB/cm and electro-optical modulation efficiencies as high as 5°/V/mm have been obtained in single mode waveguides employing a novel buried structure in GaInAsP/InP grown by LPMOCVD and processed by selective chemical etching. Such modulators are potentially excellent candidates for integrated optoelectronics.
    Add to favourites
    Export citations
Novel approach to discrete interpolation using the subsequence FHT
  • Author(s): C.-Y. Hsu  and  T.-P. Lin
  • Source: Electronics Letters, Volume 24, Issue 4, p. 223 –224
  • DOI:  10.1049/el:19880149
  • Type: Article
  • + Show details - Hide details
  • p. 223 –224 (2)
    A novel approach to discrete interpolation of finite-duration real sequences using subsequences with the fast Hartley transform (FHT) is presented. It is shown that accuracy can be improved by decomposing the signal into an ordered set of subsequences. This development is also convenient because it permits the use of inverse fast Hartley transforms (IFHT) that are always the same size as the original FHT. This approach is also appropriate for the parallel processing of each subsequence.
    Add to favourites
    Export citations
New realisations of first-order two-dimensional all-pass and all-pole digital filters
High mobility two-dimensional electron gas in InP/Ga0.47In0.53As heterojunctions grown by low-pressure organometallic vapour phase epitaxy
  • Author(s): P.J.A. Thijs ; J.M. Lagemaat ; R. Woltjer
  • Source: Electronics Letters, Volume 24, Issue 4, p. 226 –227
  • DOI:  10.1049/el:19880151
  • Type: Article
  • + Show details - Hide details
  • p. 226 –227 (2)
    The two-dimensional electron gas in InP/GaInAs heterojunctions, grown by LP-OMVPE, showed Hall mobilities as high as 164 000 and 103 000 cm2/Vs at 4 K and 80 K, respectively. A maximum Hall mobility of 172 000 cm2/Vs was measured at 20 K. Shubnikov-de Haas oscillations measured at 200 mK in magnetic fields up to 20 T indicated the total absence of parallel conduction. By illuminating the sample it was possible to populate the second electrical sub-band at a total carrier density ns = 4.4 × 1011 cm−2.
    Add to favourites
    Export citations
Microwave pnp AlGaAs/GaAs heterojunction bipolar transistor
  • Author(s): B. Bayraktaroglu ; N. Camilleri ; S.A. Lambert
  • Source: Electronics Letters, Volume 24, Issue 4, p. 228 –229
  • DOI:  10.1049/el:19880152
  • Type: Article
  • + Show details - Hide details
  • p. 228 –229 (2)
    The microwave performance of a pnp AlGaAs/GaAs heterojunction bipolar transistor was demonstrated for the first time. Common emitter current gains of 60 were obtained using MOCVD grown structures with 100 nm thick base layers and self-aligned emitter-base contacts. ft and fmax values were 12 and 20 GHz respectively. Under common-base configuration, 8 dB gain was obtained at 10 GHz. Device performance was characterised under CW and pulsed conditions.
    Add to favourites
    Export citations
Tm-pass polariser using metal-clad waveguide with high index buffer layer
15.6 GHz HBT microstrip oscillator
  • Author(s): S.R. Lesage ; M. Madihian ; N. Hayama ; K. Honjo
  • Source: Electronics Letters, Volume 24, Issue 4, p. 230 –232
  • DOI:  10.1049/el:19880154
  • Type: Article
  • + Show details - Hide details
  • p. 230 –232 (3)
    This letter describes the design and performance of the first reported Ku-band HBT oscillator. The circuit was implemented in microstrip on an alumina substrate. The device used was a fully self-aligned AlGaAs/GaAs HBT using side wall technology. An output power of +6.5 dBm was achieved at 15.6 GHz with a collector efficiency of 11%. The phase noise was −60 dBc/Hz at 10 kHz offset, which is comparable to that of a silicon bipolar oscillator, and 20 dB less than that for a GaAs FET oscillator at the same frequency band.
    Add to favourites
    Export citations
Dielectric waveguide channel dropping filter using 3 dB couplers and bandstop gratings
Another public-key distribution system based on matrix rings
Performance of optical receivers incorporating multiemission superlattice avalanche photodiodes
  • Author(s): R.S. Fyath  and  J.J. O'Reilly
  • Source: Electronics Letters, Volume 24, Issue 4, p. 234 –235
  • DOI:  10.1049/el:19880157
  • Type: Article
  • + Show details - Hide details
  • p. 234 –235 (2)
    Recently interest has been expressed in superlattice avalanche photodiodes (SAPDs) in which the initiating carrier can impact more than one ionisation per stage, as a further step towards the solid-state photomultiplier. This letter indicates that these advanced SAPDs are likely to offer improved receiver sensitivity, compared with normal SAPDs, only if the residual hole ionisation is kept to an extremely low value.
    Add to favourites
    Export citations
Electron beam sampling of IC-internal GHz signals
1.5 μm λ/4-shifted DFB LD filter and 100 Mbit/s two-channel wavelength signal switching
  • Author(s): T. Numai ; M. Fujiwara ; N. Shimosaka ; K. Kaede ; M. Nishio ; S. Suzuki ; I. Mito
  • Source: Electronics Letters, Volume 24, Issue 4, p. 236 –237
  • DOI:  10.1049/el:19880159
  • Type: Article
  • + Show details - Hide details
  • p. 236 –237 (2)
    A 1.5 μm tunable wavelength filter was studied. A 1.5 μ λ/4-shifted distributed feedback laser diode (DFB LD) was applied as an effective single wavelength selective filter. A wavelength switching experiment in a 100 Mbit/s two-channel wavelength multiplexed system was successfully demonstrated by using the tunable λ/4 shifted DFB LD filter.
    Add to favourites
    Export citations
Gate coupling and floating-body effects in thin-film SOI MOSFETs
  • Author(s): S.S. Tsao ; D.R. Myers ; G.K. Celler
  • Source: Electronics Letters, Volume 24, Issue 4, p. 238 –239
  • DOI:  10.1049/el:19880160
  • Type: Article
  • + Show details - Hide details
  • p. 238 –239 (2)
    Thin-film, silicon-on-insulator (SOI) MOSFETs exhibit bias-dependent suppression of the kink effect. For zero or positive back gate bias, the well known kink effect is suppressed but the threshold voltage depends strongly on back gate bias. For sufficiently negative back gate bias (as might be required for total-dose radiation-hard applications), the kink effect reemerges and the threshold voltage depends instead on the applied drain voltage.
    Add to favourites
    Export citations
780 nm AlGaAs DFB lasers fabricated by MOCVD
Analysis of planar bulk acoustic wave devices
  • Author(s): E. Elias  and  A. Jhunjhunwala
  • Source: Electronics Letters, Volume 24, Issue 4, p. 240 –242
  • DOI:  10.1049/el:19880162
  • Type: Article
  • + Show details - Hide details
  • p. 240 –242 (3)
    The bulk acoustic waves launched in a piezoelectric crystal by an interdigital transducer, considered earlier as a spurious response in SAW devices, are now usefully employed in planar bulk acoustic wave (BAW) devices. This paper presents the results of a theoretical analysis of bulk wave response in a material. The analysis enables one to design BAW devices with a more desirable response than those obtained so far.
    Add to favourites
    Export citations
Super low noise HEMT using focused ion beam lithography
  • Author(s): K. Nagahama ; M. Nakanishi ; Y. Sasaki ; K. Hosono ; H. Morimoto ; T. Katoh ; R. Hirano ; T. Murotani ; A. Kawagishi
  • Source: Electronics Letters, Volume 24, Issue 4, p. 242 –243
  • DOI:  10.1049/el:19880163
  • Type: Article
  • + Show details - Hide details
  • p. 242 –243 (2)
    Focused ion beam lithography is applied for the first time to low noise HEMTs for delineating a mushroom shaped quarter micron gate. The very low noise performance obtained, which is of 0.68 and 0.83 dB minimum noise figure at 12 and 18 GHz respectively, shows that focused ion beam lithography is very promising for super low noise HEMT applications.
    Add to favourites
    Export citations
Theory of tapering single-mode optical fibres by controlled core diffusion
  • Author(s): C.P. Botham
  • Source: Electronics Letters, Volume 24, Issue 4, p. 243 –245
  • DOI:  10.1049/el:19880164
  • Type: Article
  • + Show details - Hide details
  • p. 243 –245 (3)
    The feasibility of tapering the core of a fluorine-doped monomode fibre by controlled thermal diffusion is investigated. Numerical calculations suggest that operating temperatures of 1100–1600°C for heating times of less than one hour should produce substantial broadening of the fundamental mode field. Experimental measurements have confirmed the effect. Implications for optical connector technology are discussed.
    Add to favourites
    Export citations
Tapers in single-mode optical fibre by controlled core diffusion
Erratum: Bit error ratio of CPFSK coherent optical receivers

Most viewed content for this Journal

Article
content/journals/el
Journal
5
Loading

Most cited content for this Journal

Print this page
This is a required field
Please enter a valid email address