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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 25, Issue 9, 27 April 1989

Volumes & issues:

Volume 25, Issue 9

27 April 1989

Novel ion-assisted antireflection coatings for lithium niobate devices
5.5 GHz multiple quantum wellreflection modulator
Correlation of tunnelling currents and tunable luminescence in selectively diffused nipi LEDs
  • Author(s): D.E. Ackley ; J. Mantz ; H. Lee ; N. Nouri ; R. Cheponis ; C.-L. Shieh
  • Source: Electronics Letters, Volume 25, Issue 9, p. 560 –561
  • DOI:  10.1049/el:19890382
  • Type: Article
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  • p. 560 –561 (2)
    Measurements of the current/voltage characteristics and electroluminescence spectra of nipi LEDs with selectively diffused contacts have been performed over the temperature range 3-300 K. Good correlation has been observed between the forward characteristics of the diodes and the tuning of the electroluminescence. Analysis of the I/V characteristics indicates that the recombination occurs by electron tunnelling through the parabolic potential barriers.
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Accurate analytical approximations for error function and its integral
  • Author(s): P. Van Halen
  • Source: Electronics Letters, Volume 25, Issue 9, p. 561 –563
  • DOI:  10.1049/el:19890383
  • Type: Article
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  • p. 561 –563 (3)
    Analytical expressions for the error function and the integral of the error function, which can be used in the calculation of electric field and potential distribution in semiconductor junctions with a Gaussian doping profile, are presented. For both functions, the complete x-interval, ranging from 0 to infinity, is handled with a single expression. The absolute accuracy of the analytical expressions for all x-values is better than ±1.6×10−9for the error function and better than ±3.7×10−8 for the integral of the error function.
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Picosecond pulse amplification by electrically pulsed semiconductor optical amplifiers
Bulk silicon technology for complementary MESFETs
  • Author(s): U. Magnusson ; J. Tiren ; A. Söderbärg ; M. Rosling ; Ö. Grelsson ; H. Bleichner ; J.O. Nylander ; S. Berg
  • Source: Electronics Letters, Volume 25, Issue 9, p. 565 –566
  • DOI:  10.1049/el:19890385
  • Type: Article
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  • p. 565 –566 (2)
    A technology for fabrication of complementary silicon MESFETs on bulk silicon substrates has been developed. The technology is similar to CMOS technology, and utilises n-silicon substrates. P-wells are used for the n-channel devices. Device isolation was achieved by trench etching. The silicidcs of Er and Pt were used as gate Schottky contacts. P-and n-channel characteristics are presented together with subthreshold behaviour and preliminary results regarding radiation hardness. Also, results from two-dimensional simulations of the devices are presented.
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High-contrast reflection modulation at normal incidence in asymmetric multiple quantum well Fabry-Perot structure
  • Author(s): M. Whitehead  and  G. Parry
  • Source: Electronics Letters, Volume 25, Issue 9, p. 566 –568
  • DOI:  10.1049/el:19890386
  • Type: Article
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  • p. 566 –568 (3)
    We have modelled the properties of a multiple quantum well pin diode optical modulator with the natural semiconductor reflectivity (R ≈ 0.3) at its front surface and a high reflector (R ≈ 0.95), such as an integrated semiconductor quarterwave stack, at the back. By using resonant electroabsorption, rather than electrorefraction, our calculations show that it is possible to achieve contrast ratios of over 200, with less than 3dB insertion loss.
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Highly uniform, high quantum efficiency GaInAsSb/AlGaAsSb double heterostructure lasers emitting at 2.2 μm
  • Author(s): J.L. Zyskind ; J.C. Dewinter ; C.A. Burrus ; J.C. Centanni ; A.G. Dentai ; M.A. Pollack
  • Source: Electronics Letters, Volume 25, Issue 9, p. 568 –570
  • DOI:  10.1049/el:19890387
  • Type: Article
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  • p. 568 –570 (3)
    GaInAsSb/AlGaAsSb double heterostructure lasers with low pulsed threshold current density were grown previously by liquid-phase epitaxy using a complicated five-layer structure to relieve the strain arising from graded cladding layers. Double heterostructures have now been grown over a narrower temperature range to minimise this grading. These simpler three-layer DH lasers have high room-temperature quantum efficiencies (5.4% per facet) and low broad-area threshold current densities (2.6 kA/cm2) which are uniform from chip to chip.
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Transmission properties of some hollow glass waveguides at 10.6 μm wavelength
Deadlock-free window algorithm with limited splitting for multiple access channels
Nearly ideal enhanced barrier height Schottky contacts to n-InP for MESFET applications
  • Author(s): A.A. Iliadis
  • Source: Electronics Letters, Volume 25, Issue 9, p. 572 –574
  • DOI:  10.1049/el:19890390
  • Type: Article
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  • p. 572 –574 (3)
    We report the substantial enhancement of the Schottky barrier height of n-InP, using a new surface passivation process. Au contacts on the passivated surface resulted in nearly ideal Schottky diodes with barrier heights as large as 0.83 eV, ideality factors between 1.02 and 1.17 and high breakdown voltages. The passivation is found to promote the formation of a phosphorus oxide at the interface, which is believed to be responsible for the enhancement of the barrier height. The highquality of the contacts makes them ideal for InP MESFET gate electrodes.
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16-channel optical FDM distribution/transmission experiment utilising multichannel frequency stabiliser and waveguide frequency selection switch
Phase error free linc modulator
  • Author(s): S. Tomisato ; K. Chiba ; K. Murota
  • Source: Electronics Letters, Volume 25, Issue 9, p. 576 –577
  • DOI:  10.1049/el:19890392
  • Type: Article
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  • p. 576 –577 (2)
    A new technique for linear amplification with nonlinear components (LINC) is described. LINC implementation is thought to be very difficult because of its sensitivity to phase error caused by the difference in electrical length between two power amplifier branches. The allowable limit of phase error for achieving the 60 dB suppression of the adjacent channel interference (ACI) power is estimated for roll-off bandlimited offset QPSK (OQPSK). Then, a compensating method for this phase error is presented. By using the proposed method, sufficient out-of-band spectrum suppression for mobile radio application is obtained. An output power of 7.5 W and a power efficiency of 21% are experimentally confirmed.
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Key changeable ID-based cryptosystem
Novel strained quantum well laser grown by MOVPE
  • Author(s): J.N. Tothili ; L. Westbrook ; C.B. Hatch ; J.H. Wilkie
  • Source: Electronics Letters, Volume 25, Issue 9, p. 578 –580
  • DOI:  10.1049/el:19890394
  • Type: Article
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  • p. 578 –580 (3)
    Strained-layer broad-area lasers have been grown by MOVPE. The structures contain 3.5nm-wide Ga0.3In0.7As quantum wells. They emit close to 1.5μm and have been made to lase under current injection. These structures were compared with similar lasers containing unstrained 7.0n m-wide Ga0.47In0.53As quantum wells also emitting at 1.5μ m. No improvement has been found in Jth (933 cm−2) or T0 (47 K) in the case of the strained structure, despite the expected band structure modification.
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MOCVD-grown AlInAs/GaInAs MODFET with drain currents higher than 1.3 Am/m
  • Author(s): W.-P. Hong ; G.-K. Chang ; R. Bhat ; W. Chan ; B. van der Gaag ; P. Lin ; J.H. Abeles
  • Source: Electronics Letters, Volume 25, Issue 9, p. 580 –581
  • DOI:  10.1049/el:19890395
  • Type: Article
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  • p. 580 –581 (2)
    Very high-density and high-mobility AlInAs/GaInAs modulation-doped heterostructures have been successfully grown by low-pressure MOCVD. FETs, having gate lengths of 0.25 μm, fabricated from these heterostructures show transconductances as high as 700mS/mm, and drain saturation currents in excess of l. 3mA/mm at Vgs=0V This current density is among the highest yet reported for FETs grown by any technique. The extracted current-gain cutoff frequency is 78 GHz.
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Transient analysis of ferrite twin-toroid phase shifter by spatial network method
Monolithic integration of pseudomorphic power and low-noise HEMTs
  • Author(s): P. Saunier ; H.Q. Tserng ; H.D. Shih ; K. Bradshaw
  • Source: Electronics Letters, Volume 25, Issue 9, p. 583 –584
  • DOI:  10.1049/el:19890397
  • Type: Article
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  • p. 583 –584 (2)
    Monolithic integration of pseudomorphic power and low-noise high electron mobility transistors (HEMTs) on a GaAs substrate has been demonstrated using specially designed multiple epitaxial layers. MBE-grown layers with three heterojunctions were selectively recessed to provide optimum structures for low-noise and power operations. At 18 GHz, a record power-added efficiency of 59% with 8dB gain and 0.4W/mm power density was obtained for the power HEMT. The low-noise device from the same slice achieved a noise figure of ldB with 9dB associated gain at the same frequency.
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Novel multiple reference voltage generation scheme for pipeline A/D conversion
  • Author(s): K.R. Lakshmikumar  and  K. Nagaraj
  • Source: Electronics Letters, Volume 25, Issue 9, p. 584 –586
  • DOI:  10.1049/el:19890398
  • Type: Article
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  • p. 584 –586 (3)
    A novel scheme for generating multiple reference voltages for pipeline A/D conversion is proposed. The basic idea is to develop the required reference voltages by summing the voltages from two reference voltage banks. This scheme has potential for high-speed conversion. Further, the architecture of the resistor network which forms the two voltage banks, offers a wide trade-off in power dissipation and speed while requiring a small chip area.
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Comparison of 1-bit adaptive quantisers for speech coding
  • Author(s): S.C. Hall  and  H.S. Bradlow
  • Source: Electronics Letters, Volume 25, Issue 9, p. 586 –588
  • DOI:  10.1049/el:19890399
  • Type: Article
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  • p. 586 –588 (3)
    A 1-bit version of the recently proposed generalised hybrid adaptive quantiser (GHAQ) is compared with two other 1-bitadaptive quantisers, in terms of the signal-to-noise ratio obtained when coding speech in delta modulators. The GHAQ is found to have a clear advantage, particularly when the speech is acquired by a telephone microphone. It is also shown that the optimum coefficients of the predictor can be influenced substantially by the design of the adaptive quantiser, and a technique for finding suitable coefficients in this context is described.
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560 Mbit/s optical PSK heterodyne detection using carrier recovery
Photoluminescence in InP hydrogenated by plasma exposure
  • Author(s): T. Sugino ; A. Boonyasirikool ; J.S. Shirafuji ; H. Hashimoto
  • Source: Electronics Letters, Volume 25, Issue 9, p. 590 –591
  • DOI:  10.1049/el:19890401
  • Type: Article
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  • p. 590 –591 (2)
    Hydrogenation of an InP surface has been achieved by hydrogen plasma. Exposure in the limited temperature range 95–100°C gives rise to a remarkable enhancement of the photoluminescence (PL) intensity by a factor of 5.4 compared with that of unexposed InP. On the other hand, a reduction in the PL intensity occurs at temperatures a little higher than 100°C which leads to surface damage owing to preferential dissociation of phosphorus from the surface of InP. It is confirmed by secondary ion mass spectroscopy (SIMS) that hydrogen with concentration of 1 ×1018 cm−3 diffuses into the bulk InP down to a depth of 300 nm.
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Circuit models for frequency modulation response of semiconductor lasers
Continuous-wave oscillation of holmium-doped silica fibre laser
Mutual signal gain saturation in Er3+-doped fibre amplifier around 1.54 μm wavelength
  • Author(s): K. Inoue ; H. Toba ; N. Shibata ; K. Iwatsuki ; A. Takada ; M. Shimizu
  • Source: Electronics Letters, Volume 25, Issue 9, p. 594 –595
  • DOI:  10.1049/el:19890404
  • Type: Article
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  • p. 594 –595 (2)
    Signal gain saturation characteristics of a 1.48 μm wavelength LD pumped Er3+-doped fibre amplifier are experimentally investigated for two signal channels amplifiedaround the gain peak wavelengths of 1.535 μm and 1.551 μm. The degree of gain saturation is uniquely determined by thetotal output power when the signal wavelengths are closely positioned. This feature is not suited to two-channel amplification for widely spaced wavelengths.
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11 Gbit/s optical transmission experiment using 1540nm DFB laser with non-return-to-zero modulation and pin/HEMT receiver
  • Author(s): J.L. Gimlett ; M.Z. Iqbal ; J. Young ; L. Curtis ; R. Spicer ; N.K. Cheung ; S. Tsuji
  • Source: Electronics Letters, Volume 25, Issue 9, p. 596 –597
  • DOI:  10.1049/el:19890405
  • Type: Article
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  • p. 596 –597 (2)
    An 11 Gbit/s optical transmission experiment, employing a 1540nm distributed feedback (DFB) laser modulated with non-retum-to-zero signal format and an ultrawideband pin/ HEMT receiver, is described. This is the highest data rate transmission experiment reported to date using a directly modulated DFB laser. A span of 81 km of dispersion shiftedfibre was employed resulting in a record bit rate-distance product of 890 Gbit/s km, with no observable penalty due to insertion of the fibre.
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Two-dimensional, coherent y-coupled grating surface-emitting laser arrays
  • Author(s): G.A. Evans ; N.W. Carlson ; J.M. Hammer ; M. Lurie ; J.K. Butler ; J. Connolly ; L.A. Carr ; F.Z. Hawrylo ; E.A. James ; C.J. Kaiser ; J.B. Kirk ; W.F. Reichert
  • Source: Electronics Letters, Volume 25, Issue 9, p. 597 –599
  • DOI:  10.1049/el:19890406
  • Type: Article
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  • p. 597 –599 (3)
    Two-dimensional, coherent, grating surface-emitting AlGaAs laser arrays consisting of forty (4×10)active elements have been fabricated with a multiple quantum well structure. The elements of the array are index-guided ridge lasers, connected laterally by Y-branches and coupled longitudinally with passive ridge waveguides containing second-order distributed Bragg reflectors.
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Transverse resonance method for analysing finlines
Nondestructive measuring technique for misaligned angle in polarisation-maintaining fibre coupler
Field measurement of fusion splice loss using pulse reflection method
  • Author(s): J. Peacock ; J. Scarfe ; J. Reid ; S.R. Mallinson
  • Source: Electronics Letters, Volume 25, Issue 9, p. 602 –603
  • DOI:  10.1049/el:19890409
  • Type: Article
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  • p. 602 –603 (2)
    The letter describes a field experiment to determine the feasibility of using a pulse reflection method for single-ended splice loss evaluation using an OTDR. Results show that although small errors are obtained in the splice measurement (directly related to the level of reflection caused by the OTDR) the method is reasonably accurate and practical for use on short-haul optical systems.
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16 Gbit/s, 70 km pulse transmission by simultaneous dispersion and loss compensation with 1.5 μm optical amplifiers
  • Author(s): N.A. Olsson ; G.P. Agrawal ; K.W. Wecht
  • Source: Electronics Letters, Volume 25, Issue 9, p. 603 –605
  • DOI:  10.1049/el:19890410
  • Type: Article
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  • p. 603 –605 (3)
    A scheme for using semiconductor laser amplifiers for simultaneous compensation of both the fibre loss and the fibre dispersion in the 1.5 μm region is proposed and demonstrated. Experimentally, we demonstrate propagation of 16 Gbit/s pulses over 70 km of non-dispersion-shifted fibre at 1.53 μm wavelength. This distance is four times longer than the fundamental dispersion limit for transform-limited pulses.
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Spectral index method applied to coupled rib waveguides
Monolithic wavelength-flattened 1×7 single-mode fused coupler
Second-and third-order sensitivities of microwave circuits
Npn and pnp GaInP/GaAs heterojunction bipolar transistors grown by MOCVD
AlGaAs/GaAs HBT with GaInAs cap layer fabricated by multiple-self-alignment process using one mask
Spectrum efficiency for multitransmitter simulcasting in land mobile radio
Cache memory for Prolog stack
Solid-state porosity characterisation: photothermal approach
DQDB simulation and MAC protocol analysis
  • Author(s): A. Myles
  • Source: Electronics Letters, Volume 25, Issue 9, p. 616 –618
  • DOI:  10.1049/el:19890419
  • Type: Article
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  • p. 616 –618 (3)
    The distributed queue dual bus (DQDB) metropolitan area network (MAN) is currently being standardised by IEEE 802.6. This letter reports on a characteristic of the DQDB MAC protocol, found using simulation, which causes the end stations to experience higher delays than the middle stations under certain conditions. One mechanism is described to explain the phenomenon along with a modification to improve the protocol's behaviour.
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Linear pulse distortion effects in applications of semiconductor optical amplifiers to local network

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