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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 21, Issue 21, 10 October 1985

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Volume 21, Issue 21

10 October 1985

Combinatorial codes
10–30 GHz monolithic GaAs travelling-wave divider/combiner
  • Author(s): H.Q. Tserng  and  P. Saunier
  • Source: Electronics Letters, Volume 21, Issue 21, p. 950 –951
  • DOI:  10.1049/el:19850671
  • Type: Article
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  • p. 950 –951 (2)
    A four-way monolithic GaAs travelling-wave power divider/combiner has been designed, fabricated and evaluated. With a design centre frequency of 20 GHz, a bandwidth of from 10 GHz to 30 GHz has been measured. The insertion loss per dividing or combining action is less than 0.5 dB, with isolation between ports no worse than 20 dB. The input/output VSWRs are better than 2:1 across the same band. This divider/combiner can readily be used with monolithic GaAs power FET amplifiers to produce a several-fold increase in output powers over the 10 to 30 GHz frequency range.
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High-speed long-wavelength optical modulation in InGaAs/InAlAs multiple quantum wells
  • Author(s): K. Wakita ; Y. Kawamura ; Y. Yoshikuni ; H. Asahi ; S. Uehara
  • Source: Electronics Letters, Volume 21, Issue 21, p. 951 –953
  • DOI:  10.1049/el:19850672
  • Type: Article
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  • p. 951 –953 (3)
    A long-wavelength optical modulator has been fabricated which makes use of an electroabsorption effect in multiple quantum wells (MQWs). Here, InGaAs/InAlAs MQWs are prepared in a PIN configuration using molecular beam epitaxy (MBE). The rise time of the detected pulse modulation signal has been measured at 190 ps. This response level has been attributed to the detecting system response and RC time constant, and not to such intrinsic effects as carrier lifetime.
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Single-crystal silicon: a new material for 1.3 and 1.6 μm integrated-optical components
Possible fused fibre in-phase/quadrature measuring multiport
Fabrication of n+ ledge channel structure for GaAs FETs with a single lithography step
Stabilisation of external optical feedback phase in a semiconductor laser
Chirping in 1.55 μm vapour-phase-transport distributed feedback (VPTDFB) semiconductor lasers under picosecond gain switching and 4 GHz modulation
  • Author(s): Chinlon Lin  and  T.L. Koch
  • Source: Electronics Letters, Volume 21, Issue 21, p. 958 –960
  • DOI:  10.1049/el:19850677
  • Type: Article
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  • p. 958 –960 (3)
    VPTDFB semiconductor lasers have been shown to exhibit particularly low transient frequency chirp resulting in record distances for dispersive fibre transmission at 2 to 4 Gbit/s rates. The letter reports experimental study of chirping in 1.55 μm VPTDFB lasers under the demanding situation of high-speed modulation with high pulse on/off ratios. The laser was modulated with 100 ps current pulses from a comb generator, or with high-frequency RF at 4 GHz. It is found that the laser's chirped linewidth is between 2 to 8 Å for modulation on/off ratios from 4:1 to more than 20:1. We infer that at high laser pulse on/off ratios there will be significant pulse distortion at 8 to 10 Gbit/s rates for fibre distance of ≳≫60 km even with these low chirp VPTDFB lasers. However, the exact nature of this distortion and its system impact in dispersive fibre transmission may depend in detail on the specific laser parameters and system operating conditions.
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Growth of thin-film lithium niobate by molecular beam epitaxy
Via holes for GaAs MMICs fabricated using reactive ion etching
Configuration selection for two-layer memory network pattern classifiers
2400 bit/s DMSK modem for mobile satellite service
Comment: Fast method for calculating cutoff frequencies in single-mode fibres with arbitrary index profiles
Reply: Fast method for calculating cutoff frequencies in single-mode fibres with arbitrary index profiles
Positive/negative reflection-type SAW reflectors on ST-quartz using new fabrication technique
Polarisation effects in SAW acousto-optic interactions
Picosecond optical pulse compression from gain-switched 1.3 μm distributed-feedback laser diode through highly dispersive single-mode fibre
  • Author(s): A. Takada ; T. Sugie ; M. Saruwatari
  • Source: Electronics Letters, Volume 21, Issue 21, p. 969 –971
  • DOI:  10.1049/el:19850686
  • Type: Article
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  • p. 969 –971 (3)
    The first demonstration to compress the linearly chirped optical pulses from a gain-switched distributed-feedback laser diode (DFB-LD) is described at 1.3 μm wavelength. By travelling through a highly dispersive single-mode fibre with 48 ps/nm normal dispersion, a 26 ps (FWHM) pulse having red-shift frequency chirping of 85 GHz (FWHM) is compressed to 8.3 ps with the time-bandwidth product of 0.71.
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Frequency-dependent SNR for time-base distortions in magnetic recording
Monotonic descent algorithm to choose pulse locations in the excitation sequence of a multipulse speech coder
Postmetallisation annealing of aluminium-silicon gate MOS capacitors
Gain saturation effects in supermodes of phase-locked semiconductor laser arrays
  • Author(s): J. Katz  and  W.K. Marshall
  • Source: Electronics Letters, Volume 21, Issue 21, p. 974 –976
  • DOI:  10.1049/el:19850690
  • Type: Article
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  • p. 974 –976 (3)
    A basic modal analysis that includes gain saturation effects in phase-locked semiconductor laser arrays is presented. For a particular supermode operation, different lasers in the array emit different amounts of light, and hence their (waveguide) propagation constants are modified differently. Solving the lasers' rate equations self-consistently with the coupled-mode wave equations seems to provide an answer that is in much better agreement with experimental results than the result using only the coupled-mode analysis.
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Logic performance of Si3N4-n GaAs quasinormally off MISFETs
Resolution and sampling rate needed for quantisation of a narrowband signal in wideband noise
Algorithm for multichannel LMS adaptive filtering
Measurement of linewidth broadening factor in gain-switched InGaAsP injection lasers by CHP method
  • Author(s): M. Osiński ; D.F.G. Gallagher ; I.H. White
  • Source: Electronics Letters, Volume 21, Issue 21, p. 981 –982
  • DOI:  10.1049/el:19850694
  • Type: Article
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  • p. 981 –982 (2)
    First measurements of the semiconductor laser linewidth broadening factor α using a recently proposed CHP (chirp-halfwidth product) method are reported. Gain-switched optical pulses have been generated by sinusoidal RF and comb generator drive. The simultaneous recording of streak-camera and monochromator traces provides the required data for determination of α. The values of α between 6 and 7.5 are obtained for a 1.3 μm mesa laser. Computer simulations predict that the CHP formula should provide an estimate of α within ±15% for either comb generator or hard sinusoidal drive.
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SAGM avalanche photodiode optical receiver for 2 Gbit/s and 4 Gbit/s
PLA folding algorithm from compatibility relations
  • Author(s): N.N. Biswas
  • Source: Electronics Letters, Volume 21, Issue 21, p. 984 –986
  • DOI:  10.1049/el:19850696
  • Type: Article
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  • p. 984 –986 (3)
    The letter reports an algorithm for the folding of programmable logic arrays. The algorithm is valid for both column and row folding, although it has been presented considering only the simple column folding. The pairwise compatibility relations among all the pairs of the columns of the PLA are plotted in a matrix called the compatibility matrix of the PLA. A foldable compatibility matrix (FCM), a new concept defined in the letter, is then derived from the compatibility matrix. Once an FCM is obtained, the ordered pairs of fold-able columns and the reordering of the rows are readily determined.
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Analysis of asymmetrical coplanar waveguide and coplanar strip lines with anisotropic substrate
Radially anisotropic lightguide mode selector
PnP-type InP/InGaAsP/InP bipolar transistor
  • Author(s): L.M. Su ; H. Schroeter-Janssen ; K.C. Li ; N. Grote
  • Source: Electronics Letters, Volume 21, Issue 21, p. 989 –990
  • DOI:  10.1049/el:19850699
  • Type: Article
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  • p. 989 –990 (2)
    A PnP double-heterostructure InGaAsP/InP bipolar transistor was fabricated which is capable of bilateral operation. Forward and reverse current gains of about 15 and 5, respectively, were achieved. In the emitter-up configuration, an offset voltage of 1 V, believed to be due to the valence band discontinuity at the base/collector heterojunction, occurs in the Ic/VCE characteristics.
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Scanning acoustic microscopy using PVDF concave lenses
Measurement of optical bistability in an InGaAsP laser amplifier at 1.5 μm
1.3 μm edge-emitting diodes launching 250 μW into a single-mode fibre at 100 mA
Performance of AFC for phase noise reduction of optical sources
  • Author(s): B. Glance
  • Source: Electronics Letters, Volume 21, Issue 21, p. 994 –996
  • DOI:  10.1049/el:19850703
  • Type: Article
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  • p. 994 –996 (3)
    The letter evaluates the use of an automatic frequency control (AFC) circuit for reducing the phase noise of an optical source. The results show that this type of circuit reduces efficiently only the low-frequency variations of the phase noise. They also show that the high-frequency components of the phase noise can be significantly enhanced relative to those of the free-running source if the product of the loop gain by the loop bandwidth is made too large. These effects result from the time delay presented by the error signal and by the large loop gain needed to reduce sufficiently the phase noise of the optical source.
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Floating FDNR employing a new CCII− conveyor implementation
Simple formulas for the characteristics of limiter phase detectors
Delay-triggered optical switching in twin-stripe IRW lasers
  • Author(s): D. Maclean ; I.H. White ; J.E. Carroll ; R.G. Plumb
  • Source: Electronics Letters, Volume 21, Issue 21, p. 999 –1000
  • DOI:  10.1049/el:19850706
  • Type: Article
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  • p. 999 –1000 (2)
    We report a novel switching mechanism in InGaAsP twin-stripe IRW lasers operating under pulsed conditions at 1.3 μm wavelength. An interesting feature of the switch is its ability to discriminate differential delays between the arrival of 10 ns rise time drive pulses to a resolution of less than 200 ps. The switch is caused by changes in the charge carrier density of less than 0.5% which suggests subpicojoule switching energies.
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Switched-capacitor ladder filters with zero worst-case sensitivity at reflection zeros
Two new types of hazard in asynchronous circuits
Addendum: Enhanced performance of 2 μm N-MOSFETs in doubly recrystallised SOS films
Erratum: New DC-free line code of minimum bandwidth with increased eye width
Erratum: Limits to power transmission in optical fibres

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