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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 28, Issue 9, 23 April 1992

Volumes & issues:

Volume 28, Issue 9

23 April 1992

MOS circuit for nonlinear Hebbian learning
  • Author(s): M.H. Cohen  and  A.G. Andreou
  • Source: Electronics Letters, Volume 28, Issue 9, p. 809 –810
  • DOI:  10.1049/el:19920512
  • Type: Article
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  • p. 809 –810 (2)
    An analogue MOS circuit that implements a nonlinear Hebbian learning rule is presented. The circuit has two differential inputs (voltages) and yields an output (current) which approximates the product of a cubic and a hyperbolic tangent functions of the two input voltages. This has been successfully incorporated in an analogue integrated circuit implementation of the Herault-Jutten neuromorphic network.
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Node synchronisation for high rate convolutional codes
  • Author(s): J. Sodha  and  D. Tait
  • Source: Electronics Letters, Volume 28, Issue 9, p. 810 –812
  • DOI:  10.1049/el:19920513
  • Type: Article
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  • p. 810 –812 (3)
    A node synchronisation technique for rate (ν − l)/ν convolutional codes is presented which can resolve a loss of node synchronisation with only a single trial. The algorithm, which is implemented external to the decoder, is based on extracting evidence in support of the in-sync or off-sync hypotheses from the syndrome and other sequences associated with the convolutionally encoded received channel symbols. Simulation results are presented for rate R = (ν − l)/ν punctured codes derived from the well known standard NASA, constraint length 7, rate 1/2 code.
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Performance potential of silicon bipolar transistors
  • Author(s): S. Marksteiner ; A. Felder ; T.F. Meister
  • Source: Electronics Letters, Volume 28, Issue 9, p. 812 –814
  • DOI:  10.1049/el:19920514
  • Type: Article
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  • p. 812 –814 (3)
    The performance potential of silicon bipolar transistors is investigated by device simulation. Using a one-dimensional drift-diffusion equation solver, the SPICE parameters of selfaligned transistors are extracted from doping profiles and device geometries. These parameters are used to predict the CML gate delay for different doping profiles. The validity of this extraction procedure is verified by comparison with experimental data. For a double-diffusion type doping profile with a pinch resistance of 15kΩ/□, a transit frequency of 56GHz and a CML gate delay of ∼15ps are achievable. With a doping profile including a low-doped emitter region and a high base doping concentration, significant improvements are found: A transit frequency of 81.6GHz and a pinch resistance of 10kΩ/□ enable CML gate delay times below 10 ps.
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Inband noise cancelling in FM systems: the white noise case
New robust threshold setting method for frequency-hopping acquisition
  • Author(s): N.M. Stojanović  and  V.M. Jovanović
  • Source: Electronics Letters, Volume 28, Issue 9, p. 815 –817
  • DOI:  10.1049/el:19920516
  • Type: Article
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  • p. 815 –817 (3)
    A new, very robust threshold setting method for the serial search acquisition of frequency hopping (FH) waveforms, the ‘reference channel detector’ (RCD), is proposed and analysed. It is shown that this detector has considerable immunity when subjected to large signal dynamics and pulse jamming. Especially in pulse jamming, this procedure is a much more appropriate solution than the constant and adaptive threshold setting methods reported previously.
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10 Gbit/s, 1200 km error-free soliton data transmission using erbium-doped fibre amplifiers
10 Gbit/s timing recovery circuit using dielectric resonator and active bandpass filters
  • Author(s): P. Monteiro ; J.N. Matos ; A. Gameiro ; J.R.F. da Rocha
  • Source: Electronics Letters, Volume 28, Issue 9, p. 819 –820
  • DOI:  10.1049/el:19920518
  • Type: Article
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  • p. 819 –820 (2)
    A clock recovery circuit that employs a dielectric resonator, designed for the 10.368Gbit/s demonstrator of the R1051 RACE project is described. Experimental results have shown a jitter performance and sensitivity to detuning well within usual specifications for practical links. This circuit thus provides a very attractive low cost solution for multigigabit transmission.
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Current-mode divide-by-two circuit
ECR plasma etching of chemically vapour deposited diamond thin films
  • Author(s): S.J. Pearton ; A. Katz ; F. Ren ; J.R. Lothian
  • Source: Electronics Letters, Volume 28, Issue 9, p. 822 –824
  • DOI:  10.1049/el:19920520
  • Type: Article
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  • p. 822 –824 (3)
    Arc jet deposited films of diamond have been patterned using Au or photoresist masks and electron cyclotron resonance (ECR) O2 discharges. To achieve anisotropic features, additional RF-induced DC biasing of the sample is necessary. Diamond etch rates of 2000 Å/min were obtained for 1 mtorr, 400 W O2 discharges with −80 V DC bias. The etch rates increase with either pressure or microwave power as a result of a greater density of atomic oxygen in the plasma. Chlorine (BCl3)-based discharges did not product significant etching of the diamond, but SF6/O2 mixtures had slightly faster rates than O2 alone.
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1.5 μm compressive-strained multiquantum-well 20-wavelength distributed-feedback laser arrays
  • Author(s): C.E. Zah ; P.S.D. Lin ; F. Favire ; B. Pathak ; R. Bhat ; C. Caneau ; A.S. Gozdz ; N.C. Andreadakis ; M.A. Koza ; T.P. Lee ; T.C. Wu ; K.Y. Lau
  • Source: Electronics Letters, Volume 28, Issue 9, p. 824 –826
  • DOI:  10.1049/el:19920521
  • Type: Article
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  • p. 824 –826 (3)
    The wide gain spectrum of compressive-strained multiquantum-well active layers was used to fabricate 20-wavelength distributed-feedback laser arrays. A record wide wavelength span of 131 nm in the 1.5/μm wavelength region was demonstrated. The maximum intrinsic modulation response, measured by a parasitic-free optical modulation technique, reaches 16 GHz.
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40 GHz, low half-wave voltage Ti:LiNbO3 intensity modulator
Passive filter for increasing directivity in dual polarisation antenna systems
Submilliamp threshold current (0.62 mA at 0°C) and high output power (220 mW) 1.5 μm tensile strained InGaAs single quantum well lasers
  • Author(s): P.J.A. Thijs ; J.J.M. Binsma ; L.F. Tiemeijer ; T. van Dongen
  • Source: Electronics Letters, Volume 28, Issue 9, p. 829 –830
  • DOI:  10.1049/el:19920524
  • Type: Article
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  • p. 829 –830 (2)
    The strain dependence of the threshold current density of λ = 1.5 μm wavelength tensile strained InxGa1−xAs (0.22 < x < 0.53)–InGaAsP single quantum well (SQW) lasers is reported. The optimum indium mole fraction was found to be 0.32 (1–5% strain), resulting in TM polarised lasers with threshold current densities as low as 92 A/cm2. Using this SQW, buried heterostructure lasers with 0.62 mA threshold and 220 mW CW output power were realised.
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Efficient upconversion pumping at 1.064 μm of Tm3+ -doped fluoride fibre laser operating around 1.47 μm
  • Author(s): T. Komukai ; T. Yamamoto ; T. Sugawa ; Y. Miyajima
  • Source: Electronics Letters, Volume 28, Issue 9, p. 830 –832
  • DOI:  10.1049/el:19920525
  • Type: Article
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  • p. 830 –832 (3)
    1.064 μm upconversion pumping was used to operate a highly efficient CW and Q-switched thulium (Tm3+)-doped fluoride fibre laser at around 1.47 μm. The maximum CW output power was 100 mW for a launched pump power of 570 mW. The threshold power was 200 mW, the slope efficiency 27% and the wavelength tuning width 20 nm. A peak power of 70 W was generated for Q switching at a launched pump power of 300 mW.
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High speed non-selfaligned InP/InGaAs Npn heterojunction bipolar transistor grown by low pressure metal organic vapour phase epitaxy
  • Author(s): P.M. Enquist ; D.B. Slater ; P.A. Sekula-Moise ; S.M. Vernon ; V.E. Haven ; E.D. Gagnon ; A.S. Morris ; R.J. Trew ; J.A. Hutchby
  • Source: Electronics Letters, Volume 28, Issue 9, p. 832 –833
  • DOI:  10.1049/el:19920526
  • Type: Article
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  • p. 832 –833 (2)
    Lattice matched GaInAs/InP Npn heterojunction bipolar transistors (HBTs) have been grown by low pressure metal organic vapour phase epitaxy (MOVPE) and processed with non-selfaligned fabrication techniques. The transistors exhibit a cutoff frequency of 60 GHz and maximum oscillation frequency of 32 GHz which are the highest values reported to date for GaInAs/InP HBTs grown by MOVPE.
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Perfect q-ary sequences from multiplicative characters over GF (p)
Gate-induced drain leakage current degradation and its time dependence during channel hot-electron stress in n-MOSFETs
  • Author(s): G.Q. Lo  and  D.L. Kwong
  • Source: Electronics Letters, Volume 28, Issue 9, p. 835 –836
  • DOI:  10.1049/el:19920528
  • Type: Article
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  • p. 835 –836 (2)
    The effects of channel hot-electron stress on the gate-induced drain leakage current (GIDL) in n-MOSFETs with thin gate oxides have been studied. It is found that under worst case stress, i.e. a high density of generated interface states ΔDit the enhanced GIDL exhibits a significant drain voltage dependence. Whereas ΔDit increases significantly the leakage current at low Vd, it has minor effects at high Vd. On the other hand, the electron trapping was found to increase the leakage current rather uniformly over both low and high Vd regions. In addition, GIDL degradation can be expressed as a power law time dependence (i.e. ΔIleak = A . tn), and the time dependence value n varies according to the dominant damage mechanism (i.e. electron trapping against ΔDit), similar to that reported for on-state device degradation.
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Visible light-emitting diodes consisting of AlP–GaP short-period superlattices
  • Author(s): A. Morii ; H. Okagawa ; K. Hara ; J. Yoshino ; H. Kukimoto
  • Source: Electronics Letters, Volume 28, Issue 9, p. 836 –838
  • DOI:  10.1049/el:19920529
  • Type: Article
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  • p. 836 –838 (3)
    Short-period superlattices of AlP-GaP, which form a novel class of light-emitting materials in the spectral region from red to green, were applied for the first time to visible light-emitting diodes fabricated by metal organic vapour phase epitaxy. Light emission from diodes at room temperature was found to be characteristic of the superlattices: emission spectral shift toward shorter wavelengths from red to green and emission intensity increases with decreasing the period of superlattices.
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Parallel contention resolution control for input queueing ATM switches
  • Author(s): H. Obara  and  Y. Hamazumi
  • Source: Electronics Letters, Volume 28, Issue 9, p. 838 –839
  • DOI:  10.1049/el:19920530
  • Type: Article
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  • p. 838 –839 (2)
    Input queueing ATM switches requiring fast contentionl resolution control have been negatively affected by long turn-around time (TAT) due to the distance between an input port controller and a centralised contention controller. A parallel contention resolution control for input queueing switches is presented. The proposed control allows a TAT of more than one cell slot, resulting in the potential development of a centralised contention controller an ATM switch with an aggregate capacity of 1 Tbit/s.
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Performance analysis of microcellular mobile radio systems with shadowed cochannel interferers
  • Author(s): Y.D. Yao  and  A.U.H. Sheikh
  • Source: Electronics Letters, Volume 28, Issue 9, p. 839 –841
  • DOI:  10.1049/el:19920531
  • Type: Article
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  • p. 839 –841 (3)
    A study is presented of microcellular mobile radio systems where the desired signal has Rician statistics and cochannel interferers experience lognormal shadowing as well as Rayleigh fading. This implies a Rician/Rayleigh-plus-lognormal microcell interference model. The probability density function of the signal-to-interference ratio is derived and used to evaluate the performance of microcellular systems in terms of the outage probability.
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Design of ridge waveguide couplers with carrier injection using discrete spectral index method
  • Author(s): S.V. Burke ; P.C. Kendall ; P.N. Robson ; G.J. Rees ; M.J. Adams
  • Source: Electronics Letters, Volume 28, Issue 9, p. 841 –842
  • DOI:  10.1049/el:19920532
  • Type: Article
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  • p. 841 –842 (2)
    It is shown that the design of ridge waveguide couplers with a uniformly layered refractive index profile can be extended to include the nonuniformity arising within an active layer as a result of carrier injection. This is analysed using the spectral index method combined with a degenerate perturbation approach. The simplicity of this approach makes it possible to solve design problems in which the correct mixing of the fields beneath the ridges is an essential feature of the modelling, and necessary for accuracy of design.
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Genetic tuning of digital PID controllers
Low-temperature MBE-grown In0.52Ga0.18Al0.30As/InP optical waveguides
  • Author(s): H. Künzel ; N. Grote ; P. Albrecht ; J. Böttcher ; C. Bornholdt
  • Source: Electronics Letters, Volume 28, Issue 9, p. 844 –846
  • DOI:  10.1049/el:19920534
  • Type: Article
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  • p. 844 –846 (3)
    The MBE growth of In0.52Ga0.18Al0.30As (λg = 106 μm) layers in the temperature range of 400–450°C was demonstrated to give high-quality optical waveguides which not only exhibit low propagation losses as low as 0.5 dB/cm at λ = 1.55 μm but concomitantly high resistivity of > 104 Ωcm. The refractive index of In0.52Ga0.18Al0.30As was estimated to be 3.207 ± 0.03 at λ = 1.55 μm.
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Effects of carrier transport on relative intensity noise and critique of K factor predictions of modulation response
  • Author(s): R. Nagarajan ; M. Ishikawa ; J.E. Bowers
  • Source: Electronics Letters, Volume 28, Issue 9, p. 846 –848
  • DOI:  10.1049/el:19920535
  • Type: Article
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  • p. 846 –848 (3)
    The maximum possible intrinsic modulation bandwidth in semiconductor lasers is conventionally written in terms of the K factor. Although this is often sufficient in bulk lasers, it is usually not true in quantum well lasers where carrier transport can significantly affect the high speed properties. Analytical expressions are presented, which include the effects of carrier transport, for the modulation response and the relative intensity noise in quantum well lasers. It is shown that in the presence of significant transport effects, the K factor is not an accurate measure of the maximum possible intrinsic modulation bandwidth.
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Effect of imperfect power control on cellular code division multiple access system
Frequency stabilisation of monomode semiconductor lasers to birefringent resonators
Strained single quantum well (SSQW) GaInP/AlInP visible lasers fabricated by novel shutter control method in gas source molecular beam epitaxy
  • Author(s): I. Nomura ; K. Kishino ; Y. Kaneko
  • Source: Electronics Letters, Volume 28, Issue 9, p. 851 –853
  • DOI:  10.1049/el:19920538
  • Type: Article
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  • p. 851 –853 (3)
    A novel shutter control method for growing GaInP strained layers without growth interruption by gas source molecular beam epitaxy (GSMBE) is presented. By using the method, strained single quantum well (SSQW) GaInP/AlInP visible lasers were fabricated by GSMBE, for the first time. The threshold current density of the laser was 329 A/cm2 for the compressive strained case (700 nm in wavelength) and 1.7 kA/cm2 for the tensile strained case (634 nm).
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InGaAsP/InP quantum well buried heterostructure waveguides produced by ion implantation
  • Author(s): J.E. Zucker ; K.L. Jones ; B. Tell ; K. Brown-Goebeler ; C.H. Joyner ; B.I. Miller ; M.G. Young
  • Source: Electronics Letters, Volume 28, Issue 9, p. 853 –855
  • DOI:  10.1049/el:19920539
  • Type: Article
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  • p. 853 –855 (3)
    Formation of buried InGaAsP/InP quantum well waveguides by means of phosphorus ion implantation and thermal annealing during regrowth is demonstrated. Absorption spectra of implanted and unimplanted regions are used to estimate the induced index difference, which is of the order of 1% at 1.55 μm. Calculated mode intensities are in good agreement with the observed near field intensity patterns. With this etchless implant technique, we achieve a significant reduction in propagation loss for singlemode pin waveguides relative to etched semi-insulating planar buried heterostructure waveguides fabricated from the same quantum well structure. In addition to reduced scattering loss, buried quantum well waveguides produced by ion implantation are more manufacturable because fewer and less-critical processing steps are involved.
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Estimated-queue expanded bus (EQEB) protocol for single-hop multichannel lightwave networks
  • Author(s): K.W. Cheung  and  V.W. Mak
  • Source: Electronics Letters, Volume 28, Issue 9, p. 855 –857
  • DOI:  10.1049/el:19920540
  • Type: Article
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  • p. 855 –857 (3)
    The estimated queue expanded bus (EQEB) protocol is proposed to extend the distributed queue dual bus (DQDB) protocol for multichannel operation. The EQEB can increase the bus capacity while reducing the node complexities. Network simulations for 1024 nodes on 16 channels demonstrate that a throughput of ≥0.8 per channel per bus can be achieved even under heavily overloaded conditions. Fairness of access is also demonstrated.
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Fused polished polarisation-maintaining fibre couplers
Buried channel heterojunction field-effect transistor (BCHFET)
  • Author(s): G.W. Taylor ; P.A. Kiely ; P.A. Evaldsson ; P. Cooke ; D.P. Docter
  • Source: Electronics Letters, Volume 28, Issue 9, p. 858 –860
  • DOI:  10.1049/el:19920542
  • Type: Article
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  • p. 858 –860 (3)
    A new p-channel field-effect transistor is described in which the threshold is controlled by acceptor doping in a channel below the heterointerface. The transconductance is determined by the conduction in a filled undoped quantum well at the heterointerface in addition to the doped channel. For a nominal 1 × 50 μm2 FET a transconductance of 42 mS/mm and a gate conduction of 30 μA are achieved at a gate voltage of −1V. As a p-channel FET, it is an ideal complement to N-channel HFETs. A method is proposed to incorporate the n-channel HFET and the p-channel BCHFET into a complementary inverter.
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Stable 30mW operation at 50°C for strained MQW AlGaInP visible laser diodes
  • Author(s): Y. Ueno ; H. Fujii ; H. Sawano ; K. Endo
  • Source: Electronics Letters, Volume 28, Issue 9, p. 860 –861
  • DOI:  10.1049/el:19920543
  • Type: Article
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  • p. 860 –861 (2)
    High-power strained multiquantum-well (MQW) AlGaInP visible laser diodes (LDs) have been developed. Marked improvements in threshold current density and characteristic temperature have been demonstrated. Very stable 30 mW operation at 50°C for more than 1000h has been achieved for transverse-mode stabilised +0.30% lattice-mismatched MQW LDs. The operating current increase rates are less than 10−4 h−1.
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Generalised stop-and-wait protocol
  • Author(s): F. Argenti ; A. Garzelli ; G. Benelli
  • Source: Electronics Letters, Volume 28, Issue 9, p. 861 –863
  • DOI:  10.1049/el:19920544
  • Type: Article
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  • p. 861 –863 (3)
    Automatic-repeat-request (ARQ) protocols are widely used in digital communication systems for their high reliability and simple implementation. Of the various ARQ schemes, the stop-and-wait is the simplest in terms of structure, but it achieves low throughput values, even for high signal-to-noise ratios. In the Letter a generalised stop-and-wait protocol is proposed. In this protocol some consecutive messages are sent during a transmission cycle before each stop and waiting period. This protocol retains the implementation simplicity of the classical stop-and-wait scheme, but results in a significant improvement in throughput.
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Novel fast GPS/GLONASS code-acquisition technique using low update rate FFT
  • Author(s): A.J.R.M. Coenen  and  D.J.R. van Nee
  • Source: Electronics Letters, Volume 28, Issue 9, p. 863 –865
  • DOI:  10.1049/el:19920545
  • Type: Article
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  • p. 863 –865 (3)
    A novel ‘differential’ decoding technique is proposed which enables pre-averaging instead of postintegration for a substantially low update rate ‘FFT-IFT’ correlation in sprcadspectrum (navigational) receivers. N-channel code acquisition can be performed to monitor the time dispersion with FFT time left to analyse frequency dispersion in highly reflective areas (e.g. an urban environment).
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Extended trench-gate power UMOSFET structure with ultralow specific on-resistance
Image interpolation by analogue circuit
Gradually-on structure for scan design
Efficient implementation of Gabor transforms for image compression
High-speed hybrid current-mode sense amplifier for CMOS SRAMs
Resonance frequency behaviour of microstrip resonators for thin film overlays
  • Author(s): S.M.V. Iyer  and  R.N. Karekar
  • Source: Electronics Letters, Volume 28, Issue 9, p. 873 –875
  • DOI:  10.1049/el:19920551
  • Type: Article
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  • p. 873 –875 (3)
    The effect of very thin overlays on microstrip resonating structures is studied theoretically and compared with reported experimental results using screen printed dielectric pastes. A graph of resonance frequency against log10 (overlay thickness) shows three distinct regions corresponding to different overlay thickness values. Furthermore, using the theoretical curves the relative dielectric constant of the paste material at microwave frequencies is estimated, by curve fitting. The reported data are found to agree with the theoretical predictions for all regions.
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Four wave mixing in distributed erbium-doped fibre amplifier
  • Author(s): D.M. Spirit ; G.R. Walker ; P.J. Chidgey ; E.G. Bryant ; D.L. Williams ; C.R. Batchellor
  • Source: Electronics Letters, Volume 28, Issue 9, p. 875 –876
  • DOI:  10.1049/el:19920552
  • Type: Article
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  • p. 875 –876 (2)
    The first observation of four-wave mixing in a distributed erbium-doped fibre amplifier is reported. Optical pumping of a 16 km length of fibre to achieve lossless transmission sustains the nonlinear interaction at an almost constant level, making optimum use of the long interaction length available in fibre waveguides. BER data on the effects of four-wave mixing in a multichannel coherent transmission system are reported.
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Computer-generated waveguide holograms by double-ion exchange process in glass
Effect of launch power and polarisation on four-wave mixing in multichannel coherent optical transmission system
  • Author(s): G.R. Walker ; D.M. Spirit ; P.J. Chidgey ; E.G. Bryant ; C.R. Batchellor
  • Source: Electronics Letters, Volume 28, Issue 9, p. 878 –879
  • DOI:  10.1049/el:19920554
  • Type: Article
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  • p. 878 –879 (2)
    An experimental investigation of the effects of launch power and polarisation on fibre four-wave mixing (FWM) in a multichannel coherent optical transmission system is reported. It is concluded that FWM can be an important consideration in the design of optical frequency division multiplexed transmission systems with launch powers greater than a few milliwatts in fibre with low chromatic dispersion.
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Improvements to synthesis of waveguide horns
Polarisation mode dispersion measurements in 1520 km EDFA system
Asymmetric far-field patterns emitted by symmetrically pumped twin-stripe lasers in crosscoupled-mode operation
Linear and nonlinear intersub-band optical absorption in diffusion-induced AlGaAs/GaAs quantum well at far IR wavelengths
  • Author(s): E.H. Li ; B.L. Weiss ; A. Laszcz
  • Source: Electronics Letters, Volume 28, Issue 9, p. 885 –886
  • DOI:  10.1049/el:19920558
  • Type: Article
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  • p. 885 –886 (2)
    The effect of interdiffusion on the intersub-band absorption coefficient of AlGaAs/GaAs single quantum well structures has been analysed, based on the linear and nonlinear contributions from the first and third order susceptibilities, respectively. The results show that interdiffusion may be used to tune the intersub-band absorption over a large wavelength range of tens of micrometres together with a uniform absorption coefficient.
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Composite algorithms for adaptive IIR filtering
Modified exponential bidirectional associative memories
  • Author(s): W.-J. Wang  and  D.-L. Lee
  • Source: Electronics Letters, Volume 28, Issue 9, p. 888 –890
  • DOI:  10.1049/el:19920560
  • Type: Article
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  • p. 888 –890 (3)
    Based on the Jeng exponential bidirectional associative memory (EBAM), a modified updating rule of EBAM is presented. In the recalling processes of the modified EBAM (MEBAM), the continuity assumption of the EBAM is relaxed and heterocorrelation processes run parallel with the autocorrelation processes. An energy function, which is defined and does not increase on the change of neuron states, ensures the stability of the system. Finally computer simulations demonstrates that the MEBAM has much better storage capacity than that of the Jeng EBAM.
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Security of Xinmei digital signature scheme
  • Author(s): M. Alabbadi  and  S.B. Wicker
  • Source: Electronics Letters, Volume 28, Issue 9, p. 890 –891
  • DOI:  10.1049/el:19920561
  • Type: Article
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  • p. 890 –891 (2)
    Xinmital signature scheme that uses error correcting codes in a manner similar to that of the McEliece public-key cryptosytem. It is claimed that the cryptanalytic work factor for the Xinmei system is O[(n − k)!] or O(2n−k), where n and k are the length and dimension, respectively, of the algebraic code selected for the system. In the Letter it is shown that, in some cases, the cryptanalytic work factor can be as low as O(n3).
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Low distortion up to 2 GHz in 1.55 μm multiquantum well distributed-feedback laser
  • Author(s): M. Kito ; M. Ishino ; N. Otsuka ; N. Hoshino ; K. Fujihara ; Y. Matsui ; F. Fujita
  • Source: Electronics Letters, Volume 28, Issue 9, p. 891 –893
  • DOI:  10.1049/el:19920562
  • Type: Article
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  • p. 891 –893 (3)
    The distortion characteristics of multiquantum well (MQW) distributed-feedback (DFB) lasers emitting at l.55 μm wavelength are investigated over a wide frequency range. The relaxation oscillation frequency fr of the MQW DFB laser is 13 GHz at Ib = 77 mA, which is about 1.5 times larger than that of a DFB laser with a bulk active layer. Owing to the high relaxation oscillation frequency characteristics and the good linearity of the light-output against injection-current curve of the MQW DFB laser, extremely low distortion characteristics (IM2 < − 65 dBc) are achieved up to a high modulation frequency of 2 GHz.
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Hénon stream cipher
Erratum: Error performance of differentially-detected MSK in small delay-spread Rayleigh channel
Erratum: Single element-controlled sinusoidal oscillator employing single current conveyor IC
Erratum: MOS circuit for nonlinear Hebbian learning
Erratum: Strained InGaAsP multiquantum wells for optical electroabsorption waveguide modulators
Erratum: Remote gas sensing with mid-infra-red hollow waveguide

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