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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 24, Issue 16, 4 August 1988

Volumes & issues:

Volume 24, Issue 16

4 August 1988

Low-Threshold Patterned quantum well lasers grown by molecular beam epitaxy
  • Author(s): E. Kapon ; C.P. Yun ; J.P. Harbison ; L.T. Florez ; N.G. Stoffel
  • Source: Electronics Letters, Volume 24, Issue 16, p. 985 –986
  • DOI:  10.1049/el:19880670
  • Type: Article
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  • p. 985 –986 (2)
    GaAs/AlGaAs patterned quantum well lasers were grown by molecular beam epitaxy on grooved substrates. The carrier confinement and the real-index waveguiding in these lasers rely on lateral thickness variations in the quantum well active layer. Very low threshold currents, as low as l.8mA for uncoated devices at room temperature, with 63% differential efficiency have been obtained.
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Enhanced throughput in packet radio channels with shadowing
Miniature packaged external-cavity semiconductor laser with 50 GHz continuous electrical tuning range
  • Author(s): J. Mellis ; S.A. Al-Chalabi ; K.H. Cameron ; R. Wyatt ; J.C. Regnault ; W.J. Devlin ; M.C. Brain
  • Source: Electronics Letters, Volume 24, Issue 16, p. 988 –989
  • DOI:  10.1049/el:19880672
  • Type: Article
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  • p. 988 –989 (2)
    Miniature, packaged, grating-external-cavity lasers have been developed for use in PSK. and DPSK coherent transmission systems at 1.5μm. The outside dimensions of the package are 30 × 30 × 50 mm and the optical cavity length is nominally 30 mm, resulting in a spectral linewidth < 100 kHz. The lasing wavelength is mechanically adjustable over the range 1510–1560 nm and electrically tunable over a range of 0.8 nm. With appropriate control of the grating piezos, a continuous (hop-free) tuning range of 50 GHz (0.4 nm) can be obtained.
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Simple determination of coupling coefficient in DFB waveguide structures
  • Author(s): P. Brosson ; C. Artigue ; B. Fernier ; D. Leclerc ; J. Jacquet ; J. Benoit
  • Source: Electronics Letters, Volume 24, Issue 16, p. 990 –991
  • DOI:  10.1049/el:19880673
  • Type: Article
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  • p. 990 –991 (2)
    A simple method allowing the determination of the coupling coefficient Kq of DFB waveguide structures of arbitrary type, number of layers and grating profile is proposed. The method relies on effective index determination and the fast Fourier transform of the actual grating profile. The method has been validated by comparison with the measured stopband width of liquid phase epitaxy (LPE) and gas source molecular beam epitaxy (GSMBE) grown 1.5μm DFB lasers.
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Execution of the NEC2 electromagnetic moment method code on the Inmos T800 Transputer
  • Author(s): J.J. le Roux ; P.J. Bakkes ; J.J. du plessis ; J.H. Cloete
  • Source: Electronics Letters, Volume 24, Issue 16, p. 991 –992
  • DOI:  10.1049/el:19880674
  • Type: Article
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  • p. 991 –992 (2)
    The NEC2 electromagnetic moment method code has been successfully transferred into the personal computer environment. The Inmos T800 Transputer was used to execute the code. The analysis of a 12 element log-periodic antenna was used as a benchmark to compare execution times. Execution on the Transputer was 1.5 times faster than on a DEC microVAX computer, and comparable to the speed of a DEC VAX785 computer.
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High-temperature CW operation of planar buried-ridge structure lasers at λ = 1.5μm
  • Author(s): W. Thulke  and  A. Zach
  • Source: Electronics Letters, Volume 24, Issue 16, p. 992 –993
  • DOI:  10.1049/el:19880675
  • Type: Article
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  • p. 992 –993 (2)
    GaInAsP/InP-PBRS lasers emitting at l.5μm have been fabricated by multiple liquid-phase epitaxy. Effective current confinement is achieved without current blocking layers. CW threshold current is as low as 9 mA at 25°C. Output powers per facet of up to 10mW at 80°C and 3.5 mW at 100°C are obtained. The maximum operation temperature of 110°C is the highest value yet achieved with this type of laser at 1.5μm.
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Acknowledgment schemes for window flow control in a quasi-M/D/1 cut-through switching network
Gainas pin photodiode/GaAs preamplifier photoreceiver for gigabit-rate communications systems using flip-chip bonding techniques
  • Author(s): M. Makiuchi ; H. Hamaguchi ; T. Kumai ; O. Aoki ; Y. Oikawa ; O. Wada
  • Source: Electronics Letters, Volume 24, Issue 16, p. 995 –996
  • DOI:  10.1049/el:19880677
  • Type: Article
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  • p. 995 –996 (2)
    We report on an integrated photoreceiver using a flip-chip bonding technique. The integrated photoreceiver consists of a back-illuminated GaInAs/InP pin photodiode with a small junction area and a GaAs high-impedance preamplifier having a two-stage amplifier. The quantum efficiency and the cut-off frequency of the pin photodiode were 81% and 19 GHz. This photoreceiver exhibited good practical performance characteristics, including a minimum detectable power of −29.8dBm at 1 Gbit/s, and −26.9 dBm at 2 Gbit/s.
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Accurate two-dimensional approach for capacitance calculation in microcoplanar mes transmission lines
  • Author(s): A. Benghalia ; M. Ahmadpanah ; H. Baudrand
  • Source: Electronics Letters, Volume 24, Issue 16, p. 996 –998
  • DOI:  10.1049/el:19880678
  • Type: Article
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  • p. 996 –998 (3)
    A new two-dimensional approach is proposed for the analysis of microcoplanar metal-semiconductor structures, where the depletion layer capacitance is calculated accurately after an exact determination of its boundary. The Green function, which is used to invert the Laplacian operator, is obtained by means of a conformal mapping technique to take into account the real position of the ground planes. The method constitutes a solid base for a further study of slowwave MES coplanar waveguides and, with a small change in the boundary conditions, it can be extended to the analysis of MESFET propagating structures.
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Low-loss bends in planar optical ridge waveguides
New sensitivity-enhancing scheme for a fibre-optic interferometer utilising two optical loops
Origin of residual semiconductor-laser linewidth in high-power limit
  • Author(s): K. Kikuchi
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1001 –1002
  • DOI:  10.1049/el:19880681
  • Type: Article
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  • p. 1001 –1002 (2)
    The FM noise spectrum and the spectral width of semiconductor lasers are measured in the high-power state up to 20 mW. The FM noise spectrum consists of the white noise and the 1/f noise. The spectral density of the white noise is suppressed by the increase in the output power, whereas that of the l/f noise is kept constant. This fact means that the residual linewidth in the high-power limit is caused by the l/f noise rather than the white noise.
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Frequency-locked diode laser for interferometric sensing systems
Resonant frequency analysis of dielectric ring resonators
Measurement of intermodulation products generated by structural components
Stray-free second-order circuit for correction of sample-and-hold amplitude distortion in switched-capacitor filters
Performance of shot-noise limited optical communications in presence of intersymbol interference
Electrical and microstructural characterisation of an ultrathin silicon interlayer used in a silicon dioxide/germanium-based MIS structure
  • Author(s): G.G. Fountain ; R.A. Rudder ; S.V. Hattangady ; D.J. Vitkavage ; R.J. Markunas ; J.B. Posthill
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1010 –1011
  • DOI:  10.1049/el:19880687
  • Type: Article
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  • p. 1010 –1011 (2)
    Ultrathin (1.0 nm) Si layers have been deposited on Ge(100) surfaces using remote plasma-enhanced chemical vapour deposition (RPECVD) at 350°C followed by in situ RPECVD deposition of an SiO2 insulating layer. Microstructural data from transmission electron microscopy along with elemental analysis from X-ray photoelectron spectroscopy and ion scattering spectroscopy indicate that the Si layer is present and may be pseudomorphic in nature. The formation of a Si/Ge heterojunction prior to oxide deposition minimises the formation of Ge oxides and thus controls the chemical nature of the Ge surface. Indeed, dramatic improvements in the electrical interfacial characteristics were observed in the SiO2/Si/Ge over the SiO2/Ge MIS structure.
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Mode field radius definitions for arbitrary planar single-mode optical waveguides and their relations to splice loss and propagation constant
  • Author(s): A.H. Liang  and  C.C. Fan
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1011 –1013
  • DOI:  10.1049/el:19880688
  • Type: Article
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  • p. 1011 –1013 (3)
    Root-mean-square and Laplacian mode field radius (MFR) definitions for planar single-mode optical waveguides (PSMOW) with arbitrary index profile are proposed based on the second moment of the near-field (NF) and far-field (FF) distributions. Expressions of these definitions in both NF and FF, as well as their simple relations to the propagation constant and splice loss between two identical waveguides, are derived.
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High reliability planar-type GaInAs/InP heterostructure avalanche photodiodes
Bistable operation of 0.8μm GaInAsP/AaAs lasers
Stability of differential multipass processes
Efficient power combining quasi-optic oscillator
Fused couplers function in a broad range of wavelength
Detectivity of high-gain GaAs photoconductive detectors
Capacitance of a small tubular antenna
CMOS compatible, self-biased bipolar transistor aimed at detecting maximum temperature in a silicon integrated circuit
Optical receiver with third-order capacitive current-current feedback
SC circuit for very large and accurate time constant integrators with low capacitance ratios
  • Author(s): G. Espinosa Flores-Verdad  and  F. Montecchi
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1025 –1027
  • DOI:  10.1049/el:19880698
  • Type: Article
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  • p. 1025 –1027 (3)
    A switched capacitor active integrator which realises long time constant values with low capacitance ratios is presented. The basic circuit implements a parasitic-insensitive capacitive charge division, which allows for accurate control of the equivalent time constant. The offset of the operational amplifier is reduced via a correlated-double-sampling operation, and the effect of the finite gain of the operational amplifier is also reduced with respect to classic integrators when a modified topology is used.
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High-speed accurate CMOS comparator
  • Author(s): M. Steyaert  and  V. Comino
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1027 –1028
  • DOI:  10.1049/el:19880699
  • Type: Article
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  • p. 1027 –1028 (2)
    A high-speed CMOS comparator for A/D convertors is discussed. The circuit has high resolution (better than 5 mV) in combination with high speed (clock frequencies up to 50 MHz). The advantage of the proposed structure is that no clock feedthrough is injected to the input, only one switch in a symmetrical structure is used and the effect of any current biasing on the comparator speed has been reduced.
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High-performance MESFETs in MOCVD-grown gallium arsenide on silicon
  • Author(s): D.J. Warner ; R.R. Bradley ; T.B. Joyce ; R.J.M. Griffiths
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1029 –1030
  • DOI:  10.1049/el:19880700
  • Type: Article
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  • p. 1029 –1030 (2)
    The use of MOCVD for growing device quality GaAs on silicon material has not been widely reported. This letter describes an MOCVD growth process that has allowed GaAs MESFETs to be fabricated with transconductances as high as 185 mS/mm with an operating yield of greater than 78%. The structural stability of the grown layers was good with no peeling of the GaAs from the silicon substrate during the scribing and breaking of the wafer into individual device chips.
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Optical tristability including spectral bistability using an inhomogeneously excited multielectrode DFB LD
First SiC dynistor
Natural error coding for phonetically encoded speech messages
Ultra-thin-channelled GaAs MESFET with double-δ-doped layers
Interference and long-loop phase-lock receivers
GaAs MESFETs, ring oscillators and divide-by-2 integrated circuits fabricated on MBE grown GaAs on Si substrates
  • Author(s): F. Ren ; N. Chand ; P. Garbinski ; S.J. Pearton ; C.S. Wu ; L.D. Urbanek ; T. Fullowan ; N. Shah ; M.D. Feuer
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1037 –1039
  • DOI:  10.1049/el:19880706
  • Type: Article
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  • p. 1037 –1039 (3)
    Using a very thin layer of GaAs (2.1 μm) on Si, we have fabricated GaAs MESFETs, 19 stage ring oscillators, and divide-by-2 frequency dividers with good yield. The MESFETs exhibited a maximum gm of 153 mS/mm. The DCFL 19 stage ring oscillators had a minimum propagation delay of 52ps/gate at a power dissipation of 1.3 mW/gate with a yield of 40%. The divide-by-2 circuits performed the frequency dividing operation up to 1.8 GHz.
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Characteristics of acoustic echo cancellers using sub-band sampling and decorrelation methods
Multiprocessor based system design
Modes of phase-locked diode-laser arrays of closely spaced antiguides
  • Author(s): D. Botez  and  G. Peterson
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1042 –1044
  • DOI:  10.1049/el:19880709
  • Type: Article
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  • p. 1042 –1044 (3)
    A uniform, ten-element array of closely spaced (1–3 μm) realindex depressions (antiguides), with lasing suppressed in the positive-index regions between antiguides, supports ten lasing eigenmodes. Near-field amplitude profiles and radiation losses are presented and discussed. Radiation losses of inphase and out-of-phase array modes are negligible in comparison with the radiation loss of one array element taken separately.
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Error correction capabilities of BCH codes with interleaving in Rayleigh fading channel
  • Author(s): H. Suda  and  T. Miki
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1044 –1045
  • DOI:  10.1049/el:19880710
  • Type: Article
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  • p. 1044 –1045 (2)
    Error correction capabilities of several BCH codes with different code lengths are investigated for a Rayleigh fading channel where burst bit errors occur frequently. The decoded BERs are compared under the same delay time condition for bit interleaving. Error sequences obtained from laboratory experiment are used for GMSK BER calculations. The results show that difference in the effects of code lengths on error correction capabilities is almost negligible under the slow fading with short delay time (short interleaving size) conditions.
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1.5 μm multiple-quantum-well distributed feedback laser diodes grown on corrugated InP by MOVPE
Low-drive-voltage, low-loss AlGaAs/GaAs 2 × 2 switch
  • Author(s): C. Wüthrich ; J. Faist ; W. Baer ; F.K. Reinhart
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1047 –1048
  • DOI:  10.1049/el:19880712
  • Type: Article
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  • p. 1047 –1048 (2)
    The letter reports the realisation of a 2 × 2 switch using a Mach-Zehnder interferometer with tunable coupler sections. The structure is based on a GaAs-AlGaAs double heterostructure with SnO2-doped In2O3 electrodes. At a wavelength of 1.15 μm, this device is characterised by a low switching voltage of 7.5 V and a low loss of 4 dB/cm. A high extinction ratio of 20 dB can be achieved.
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Frequency-locking of a 1.5μm DFB laser to an atomic krypton line using optogalvanic effect
Comparison of optical reflection tolerance between conventional and λ/4-shifted DFB lasers in a 2.4 Gbit/s system
  • Author(s): H. Nakano ; S. Sasaki ; S. Tsuji ; N. Chinone ; M. Maeda
  • Source: Electronics Letters, Volume 24, Issue 16, p. 1049 –1051
  • DOI:  10.1049/el:19880714
  • Type: Article
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  • p. 1049 –1051 (3)
    Effects of optical reflection on transmission characteristics with conventional fibre (1.3μm zero dispersion) are examined using 1.55μm conventional and λ/4-shifted DFB lasers. It is shown for the first time that λ/4-shifted DFB lasers are superior to conventional ones in transmission performance with optical reflection. BER floor levels of λ/4-shifted DFB lasers are lower than those of conventional ones, and do not change for the reflection level of PC-type optical connector.
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Multibit oversampled Σ-Δ A/D convertor with digital error correction
Effect of channel spacing in an optical two-channel DPSK transmission system with optical amplifiers
Photochromic dynamics and nonlinear transmission at modulated CW blue/green wavelengths in germanosilicate optical fibres
Handling isochronous and non-isochronous traffic in local area networks

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