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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 20, Issue 11, 24 May 1984

Volumes & issues:

Volume 20, Issue 11

24 May 1984

Frequency trimming for high-frequency SAW device using ultraviolet light
  • Author(s): K. Setsune ; O. Yamazaki ; K. Wasa
  • Source: Electronics Letters, Volume 20, Issue 11, p. 433 –434
  • DOI:  10.1049/el:19840300
  • Type: Article
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  • p. 433 –434 (2)
    A new technique for frequency trimming of surface-acoustic-wave (SAW) devices is demonstrated using ultraviolet light. Irradiation by ultraviolet light of a very thin SiO2 film which is fabricated on a quartz substrate makes it possible to adjust the operation frequency within an accuracy of better than ±10 kHz at 900 MHz with an insertion loss increase of less than 1 dB. This technique is applied successfully to a 668 MHz SAW resonator.
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Harmonic distortion due to laser modulation in multimode fibre optic analogue transmission
  • Author(s): K. Kaede ; R. Ishikawa ; K. Minemura ; R. Lang ; T. Furuse ; A. Ueki
  • Source: Electronics Letters, Volume 20, Issue 11, p. 434 –435
  • DOI:  10.1049/el:19840301
  • Type: Article
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  • p. 434 –435 (2)
    The effect of laser-diode frequency chirping on harmonic distortions in multimode fibre analogue transmission with direct intensity modulation was clarified experimentally with results in good agreement with the theory. The results show that the harmonic distortion can be greatly reduced by the reduction of the frequency chirping which accompanies diode-laser intensity modulation.
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Proposal for a digital pseudorandom number generator
Bandwidth limitations of log-periodic microstrip patch antenna arrays
  • Author(s): P.S. Hall
  • Source: Electronics Letters, Volume 20, Issue 11, p. 437 –438
  • DOI:  10.1049/el:19840303
  • Type: Article
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  • p. 437 –438 (2)
    Results are presented for the frequency dependence of the propagation constant of uniform microstrip patch arrays that allow the bandwidth limitations of log-periodic patch arrays to be deduced. It is found that direct coupling of the patch to the feed line limits the log-periodic bandwidth to about a 2:1 frequency range. However, the introduction of series reactance into the equivalent circuit such as by the use of overlaid patches indicate that log-periodic action over a very wide bandwidth is possible which will then be limited by the uniform substrate and production tolerances.
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Laser-diode optical switch module
Experimental studies of metal-clad tapered optical waveguides
140 GHz broadband crossbar stripline mixers with over 20 GHz instantaneous RF bandwidth
Fabrication and characteristics of ion-implanted GaAs/GaAlAs integrated injection logic inverter
  • Author(s): P. Narozny  and  H. Beneking
  • Source: Electronics Letters, Volume 20, Issue 11, p. 442 –443
  • DOI:  10.1049/el:19840307
  • Type: Article
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  • p. 442 –443 (2)
    An integrated injection logic inverter has been realised in GaAs/GaAlAs material using ion implantation and Zn diffusion. Si ions have been implanted to merge the current source with the switching transistor, whereas the Be implantation provides the base contact. The shallow p+-emitter of the pnp current source has been fabricated by Zn diffusion. Instead of a lateral pnp transistor, which is typical in I2L technology, a vertical arrangement has been used. This type of transistor shows a better current efficiency and can be fabricated with a better uniformity in terms of base width. First results of an I2L inverter with a vertical pnp transistor are shown.
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Fading rates in coherent OTDR
Annealing of Mg implants in GaAs using incoherent radiation
Low resistance alloyed ohmic contacts to Al0.48In0.52As/n+-Ga0.47In0.53As
  • Author(s): P.M. Capani ; S.D. Mukherjee ; P. Zwicknagl ; J.D. Berry ; H.T. Griem ; L. Rathbun ; L.F. Eastman
  • Source: Electronics Letters, Volume 20, Issue 11, p. 446 –447
  • DOI:  10.1049/el:19840310
  • Type: Article
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  • p. 446 –447 (2)
    A low ohmic contact resistance metallurgy and associated alloy cycles have been developed for applications to Al0.48In0.52As/Ga0.47In0.53As MODFETs (HEMTs). The metallurgy involves sequentially evaporated Ni/Ge/Au/Ag/Au layers followed by transient thermal alloy cycles. This resulted in low transfer resistances ∼0.06 Ωmm to the underlying GalnAs layer for alloying temperatures to ∼480°C.
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New mode scrambler for optical fibre measurements
Stress modification in optical fibre
Estimation of linewidth enhancement factor α of CSP-type AlGaAs lasers from measured correlation between AM and FM noises
X-band paraphase amplifier
New low-loss broadband SAW filter using unidirectional IDTs with U-shaped MSCs
  • Author(s): M. Hikita ; H. Kojima ; T. Tabuchi ; Y. Kinoshita
  • Source: Electronics Letters, Volume 20, Issue 11, p. 453 –454
  • DOI:  10.1049/el:19840315
  • Type: Article
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  • p. 453 –454 (2)
    A new low-loss broadband SAW filter is presented. A new configuration using one pair of electrically connected IDTs with an optimum number of fingers, as well as unidirectional IDTs with U-shaped MSCs, is described. Experimental results with bandwidth as wide as 10% and loss as low as 3 dB are achieved. Very accurate computer-aided design of a low-loss filter with MSCs is obtained.
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Computer-aided simulation of power MOSFET switch-mode convertors
Generalisation of the partial-power law (Brown's identity) to waveguides with lossy media
Comment: Radiometer input circuit requirements for microwave thermography
Reply: Radiometer input circuit requirements for microwave thermography
Broadband dual-depth E-plane corrugated square waveguide polariser
InGaAs/InGaAlAs/InAlAs/InP SCH-MQW laser diodes grown by molecular-beam epitaxy
Design and performance of groove-guide directional couplers
n+ -GaAs/undoped GaAlAs/undoped GaAs field-effect transistor
  • Author(s): K. Matsumoto ; M. Ogura ; T. Wada ; N. Hashizume ; T. Yao ; Y. Hayashi
  • Source: Electronics Letters, Volume 20, Issue 11, p. 462 –463
  • DOI:  10.1049/el:19840323
  • Type: Article
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  • p. 462 –463 (2)
    The first self aligned accumulation-mode GaAs MIS-like FET having an n+ -GaAs/undoped GaAlAs/undoped GaAs structure is reported. The FETs fabricated show the threshold voltage of almost zero (V̅th = 0.035 V) and very uniform (σVth = 0.013 V) characteristics, as expected. The transconductance is as high as 170 mS/mm, which is the highest value ever reported on GaAs MIS-like FETs.
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Monolithic integration of low-threshold-current 1.3 μm GaInAsP/InP DFB lasers
  • Author(s): Y. Hirayama ; J. Kinoshita ; H. Furuyama ; Y. Uematsu
  • Source: Electronics Letters, Volume 20, Issue 11, p. 463 –465
  • DOI:  10.1049/el:19840324
  • Type: Article
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  • p. 463 –465 (3)
    Two 1.3 μm GaInAsP/InP DFB lasers with low threshold currents (28 and 29 mA) were successfully integrated. Both DFB lasers operated continuously at temperatures of up to 68°C. The 12 Å separation in wavelength between the two lasers was produced by a 2 Å difference of the grating periods. A thermal interaction between the two lasers was estimated from the shift in their wavelengths.
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Efficient fibre to X-cut Ti:LiNbO3 waveguide coupling for λ = 1.32 μm
  • Author(s): R.C. Alferness  and  M.D. Divino
  • Source: Electronics Letters, Volume 20, Issue 11, p. 465 –466
  • DOI:  10.1049/el:19840325
  • Type: Article
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  • p. 465 –466 (2)
    While efficient fibre-waveguide coupling has been achieved for titanium-diffused waveguides on Z-cut Y-propagating lithium niobate crystals, previously reported results for coupling to waveguides on non-Z-cut crystals have been poor. Here we report total fibre-waveguide-fibre insertion losses as low as −1.35 dB for ∼l.5 cm-long waveguides on X-cut Y-propagating lithium niobate—the preferable orientation for polarisation conversion devices. The losses are only slightly higher than the best value for Z-cut crystals (∼ −1 dB) due to the larger waveguide mode eccentricity.
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Mobility in n-(Al, Ga)As/GaAs heterojunctions at moderate electric fields
  • Author(s): D. Chattopadhyay
  • Source: Electronics Letters, Volume 20, Issue 11, p. 466 –468
  • DOI:  10.1049/el:19840326
  • Type: Article
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  • p. 466 –468 (3)
    Hot-electron mobilities in (Al, Ga)As/GaAs single hetero-structures at 77 and 300 K are calculated for fields below 500 V/cm. Polar optic and acoustic deformation potential phonon scattering are considered, and intra- and inter-sub-band transitions in the first two sub-bands are included. The strong electron-electron interaction is assumed to enforce a displaced Maxwellian distribution function. The calculated results mostly explain the recently observed field variation of mobility.
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Tribroken-line dipole
  • Author(s): Du Jia-Cong  and  Zhong-Pei Zhang
  • Source: Electronics Letters, Volume 20, Issue 11, p. 468 –469
  • DOI:  10.1049/el:19840327
  • Type: Article
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  • p. 468 –469 (2)
    A new type of antenna structure that has a radiation performance similar to those of shaped wire antennas with maximum directivity is presented. The optimum geometry of the dipole with maximum directivity is found by applying the method of moments and the pattern search method. In addition, the dipole characteristics, like patterns and input impedance, are calculated and also compared with experimental results.
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Monolithic integrated amplifiers for a gigabit optical repeater
Monolithic multigigabit/s silicon decision circuit for applications in fibre-optic communication systems
Transient chirping in single-frequency lasers: lightwave systems consequences
  • Author(s): R.A. Linke
  • Source: Electronics Letters, Volume 20, Issue 11, p. 472 –474
  • DOI:  10.1049/el:19840330
  • Type: Article
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  • p. 472 –474 (3)
    The effect of modulation-induced laser wavelength shifts on optical transmission through dispersive fibres is shown to be a serious limiting factor at bit rates greater than 1 Gbit/s. Wavelength excursions with magnitudes as large as 6 Å are seen to occur in single-frequency lasers (C3 and DFB) during a transition from one power level to another. The wavelength shifts briefly toward shorter wavelengths and then back to the equilibrium value during turn-on and toward longer wavelengths and back during turn-off. These excursions, which are well explained by a model in which the carrier density is temporarily driven out of equilibrium by a change in injection current, last for hundreds of picoseconds or about one half of the relaxation resonance period. This time-dependent behaviour gives rise to a dramatic degradation of system performance with increasing bit rate.
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New complete processing system for recognition and classification of objects in multiple image frames
Magnetostatic band suppression at microwave frequency in triple-layered garnet films
Low-noise 140–170 GHz heterodyne receiver using quasiparticle tunnel junctions
Pattern synthesis by use of an augmented Lagrangian algorithm
High-performance GaAs-GaAlAs phase modulators for PSK optical fibre systems
  • Author(s): A.J.N. Houghton ; P.M. Rodgers ; D.A. Andrews
  • Source: Electronics Letters, Volume 20, Issue 11, p. 479 –481
  • DOI:  10.1049/el:19840335
  • Type: Article
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  • p. 479 –481 (3)
    GaAs-GaAlAs monomode phase modulators have been made from MBE-grown heterostructures using reproducible fabrication techniques. A π phase shift at 9 V was obtained for a device length of 4.2 mm. With an internal optical loss <2.5 dB and modulation capability to >1.2 Gbit s−1, these devices show superior overall performance to any previously reported semiconductor guided-wave devices.
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Proof and extension of general sensitivity formulas for lossless two-ports

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