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Online ISSN 1350-911X Print ISSN 0013-5194

Electronics Letters

Volume 18, Issue 20, 30 September 1982

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Volume 18, Issue 20

30 September 1982

Room-temperature CW operation of 1.3 μm distributed-feedback GaInAsP/InP lasers
  • Author(s): Y. Uematsu ; H. Okuda ; J. Kinoshita
  • Source: Electronics Letters, Volume 18, Issue 20, p. 857 –858
  • DOI:  10.1049/el:19820581
  • Type: Article
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  • p. 857 –858 (2)
    Distributed-feedback GaInAsP/InP lasers with a low threshold current emitting at 1.3 μm have been successfully fabricated. A minimum CW threshold current of 66 mA was obtained at room temperature. The temperature coefficient of lasing wavelength was 1 Å/°C, which is about a fifth of that for Fabry-Perot lasers. A stable single longitudinal mode was obtained up to 52°C in a p-side-up configuration.
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Amorphous-silicon TFT array for LCD addressing
  • Author(s): M.V.C. Stroomer ; M.J. Powell ; B.C. Easton ; J.A. Chapman
  • Source: Electronics Letters, Volume 18, Issue 20, p. 858 –859
  • DOI:  10.1049/el:19820582
  • Type: Article
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  • p. 858 –859 (2)
    A 64×64 element matrix array of amorphous-silicon thin-film transistors has been fabricated on a glass substrate. Using a drive scheme to simulate a 500-line display, an output voltage of 8.5 V RMS is obtained. This large output voltage is sufficient for an alphanumeric liquid-crystal display using the dyed cholesteric-nematic phase-change effect. The driving voltages for the array are compatible with LOCMOS (18 V) peripheral circuitry.
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GaSb Photodiode for detection of 1.73 μm radiation of Er:YLF laser
  • Author(s): C. Heinz  and  W. Schmidt Auf Altenstadt
  • Source: Electronics Letters, Volume 18, Issue 20, p. 859 –860
  • DOI:  10.1049/el:19820583
  • Type: Article
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  • p. 859 –860 (2)
    We have developed a GaSb photodiode for receiving the 1.73 μm radiation of a solid-state laser (Er:YLF). The diode layers have been grown by LPE on (100)-oriented Te-doped GaSb substrates. The peak value of the responsivity of the diodes is 0.55 A/W at a wavelength of 1.73 μm corresponding to a quantum efficiency of 40%. The best RA product of the diodes is 83 Ωcm2. The data are obtained without anti-reflection coating.
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Hybrid-mode feed for multiband applications having a dual-depth corrugation boundary
  • Author(s): S. Ghosh ; N. Adatia ; B.K. Watson
  • Source: Electronics Letters, Volume 18, Issue 20, p. 860 –862
  • DOI:  10.1049/el:19820584
  • Type: Article
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  • p. 860 –862 (3)
    Electrical characteristics of a hybrid-mode circular aperture horn with dual-depth corrugations are presented. It is shown that the hybrid-mode characteristics of such a horn can be optimised to give low crosspolarised radiation in two bands having arbitrary separation. This is achieved by means of appropriate choice of the depth of successive corrugations. Measured results are given for a horn designed to operate in two bands separated by 1:1.5.
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OTDR in single-mode fibre at 1.5 μm using heterodyne detection
High-quality InP surface corrugations for 1.55 μm InGaAsP DFB lasers fabricated using electron-beam lithography
Fabrication of curved structures by electron-beam lithography
Optical-waveguide microdisplacement sensor
Karnaugh map extended to six or more variables
  • Author(s): A.K. Halder
  • Source: Electronics Letters, Volume 18, Issue 20, p. 868 –870
  • DOI:  10.1049/el:19820589
  • Type: Article
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  • p. 868 –870 (3)
    Inclusion of up to four minterms in each of the sixteen cells enables a Karnaugh map to be extended for the minimisation of six-variable logical functions. The columns of minterms of the map have been so designed as to alternate as even minterm and odd minterm columns. This distinctive separation of columns would facilitate the plotting of function minterms on the map as well as the generation of prime implicants. An example illustrates the application of the extended map in the easy minimisation of a six-variable function.
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Very low threshold GRIN-SCH GaAs/GaAlAs laser structure grown by OM-VPE
  • Author(s): S.D. Hersee ; M. Baldy ; P. Assenat ; B. de Cremoux ; J.P. Duchemin
  • Source: Electronics Letters, Volume 18, Issue 20, p. 870 –871
  • DOI:  10.1049/el:19820590
  • Type: Article
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  • p. 870 –871 (2)
    In a recent publication we gave preliminary results on the lasing characteristics of a GRIN-SCH GaAs/GaAlAs laser grown by OM-VPE. The parameters of this single quantum well laser have now been further optimised, and for a quantum well thickness of 60 Å, with outer confinement layers composed of Ga0.4Al0.6As, significantly lower threshold current densities have been achieved. For a broad-area laser of cavity length 413 μm (width 140 μm) the average threshold current density is 232 A cm−2, and this decreases to 121 A cm−2 for a chip length of 1788 μm. We believe that these are the lowest lasing threshold current densities that have yet been reported.
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Dual-wavelength (GaAl)As laser
Chirp pulse transmission through a single-mode fibre
Current/frequency-modulation characteristics for directly optical frequency-modulated injection lasers at 830 nm and 1.3 μm
CW longitudinal mode spectra of multiple quantum well stripe lasers
  • Author(s): C. Lindström ; D. Halido ; D.R. Scifres ; R.D. Burnham
  • Source: Electronics Letters, Volume 18, Issue 20, p. 876 –878
  • DOI:  10.1049/el:19820594
  • Type: Article
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  • p. 876 –878 (3)
    The CW longitudinal-mode spectra of multiple quantum well AlGaAs-GaAs heterostructure proton isolated stripe lasers are studied as a function of stripe width. Laser operation corresponding to the lowest confined electron-to-heavy hole, electron-to-light hole, and to the proton-assisted second electron-to-heavy hole transition was observed. These transitions were found to be determined by the stripe width. With an optimised stripe width, laser emission on either of the heavy-hole transitions was obtained for the measured power range up to 15 mW.
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Organic piezoelectric high-frequency thin-film transducers
Short-cavity GaAlAs laser by wet chemical etching
Lower submicron pattern definition by high-voltage electron-beam lithography
Picosecond dispersionless transmission of InGaAsP injection laser pulses at the minimum chromatic dispersion wavelength in a 27 km-long single-mode fibre
  • Author(s): C. Lin ; A. Tomita ; A.R. Tynes ; P.F. Glodis ; D.L. Philen
  • Source: Electronics Letters, Volume 18, Issue 20, p. 882 –883
  • DOI:  10.1049/el:19820598
  • Type: Article
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  • p. 882 –883 (2)
    We report transmission of 60 ps InGaAsP injection laser pulses (Δλ̃7 nm) through a 27 km-long single-mode fibre at the wavelength of minimum chromatic dispersion (1.314 μm). Practically no pulse broadening was observed. We conclude that the pulse broadening due to chromatic dispersion and polarisation-mode-dispersion (if any) combined is less than 30 ps for the 27 km-long single-mode fibre as determined from experimental uncertainty.
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Power spectra of 6B4T and 3B2T codes
Ultrafast optoelectronic switching in CdS
Hybrid models of 3-port immittance convertors and current and voltage conveyors
Rectifying GaAs-GaAlAs-GaAs structures by MOCVD compositional grading
Temporal resolution of an AlxGa1−xAs/GaAs bias-free photodetector
Growth and optical properties of single-crystal metastable (GaAs)1−xGex alloys
  • Author(s): S.A. Barnett ; M.A. Ray ; A. Lastras ; B. Kramer ; J.E. Greene ; P.M. Raccah ; L.L. Abels
  • Source: Electronics Letters, Volume 18, Issue 20, p. 891 –892
  • DOI:  10.1049/el:19820604
  • Type: Article
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  • p. 891 –892 (2)
    Single-crystal metastable (GaAs)1−xGex alloys with 0≤x≤1 have been grown on (100) GaAs substrates using ultra-high-vacuum ion-beam sputter deposition. Optical absorption measurements showed that the direct gap E0 exhibited a large negative, but nonparabolic, bowing as a function of x with a broad minimum E0≃0.5 eV near 35 mole % Ge. Raman results exhibited a nonlinear ‘single-mode’ behaviour, with the longitudinal and transverse optical modes becoming degenerate at x = 1.
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Use of point contributors model for a radar target taking into account mutual coupling by double reflection
  • Author(s): G. Chassay
  • Source: Electronics Letters, Volume 18, Issue 20, p. 893 –894
  • DOI:  10.1049/el:19820605
  • Type: Article
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  • p. 893 –894 (2)
    In a previous letter we showed that the electromagnetic mutual coupling between two diffractive bodies can considerably modify the radar cross-section diagram of these bodies. We commented on the preponderance of mutual coupling by double reflection and established a new formula for the RCS of a system of two spheres, giving excellent results in practice. In this letter, we shall propose a generalisation of the previously established formulas, and shall give a law of composition for the contributions fit for use with the complex models of specular point contributors. In the second Section we shall show how it is possible to replace a model of isotropic point contributors with couplings by a model without coupling by adding imaginary isotropic points.
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InGaAsP/InP (1.3 μm) buried-crescent lasers with separate optical confinement
  • Author(s): R.A. Logan ; J.P. van der Ziel ; H. Temkin ; C.H. Henry
  • Source: Electronics Letters, Volume 18, Issue 20, p. 895 –896
  • DOI:  10.1049/el:19820606
  • Type: Article
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  • p. 895 –896 (2)
    We report that a significant improvement in the performance of InGaAsP (λ=1.3 μm) crescent lasers is obtained by introducing InGaAsP (λ=1.1 μm) cladding layers on both sides of the active layer. Such lasers grown with good reproducibility and high yield have 20–35 mA threshold currents, pulsed power outputs of up to 50 mW, with excellent output linearity, and external quantum efficiencies of 50–60%. Operation up to 90°C with 4 mW output power has been observed. Short current pulse excitation shows that these lasers are suitable for gigabit/s operation.
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Erratum: Efficient waveguide Bragg-deflection grating on LiNbO3
Erratum: RCS diagram records processing in Cheby̅shev space
Erratum: Analysis of efficiency limitations in high-low emitter back surface field silicon solar cells
Erratum: Theoretical analysis of hybrid modes in a dual-depth corrugated waveguide feed

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