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Radio and Electronic Engineer

Issue 7.8 • Date July-August 1981

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Displaying Results 1 - 13 of 13
  • Optical fibre communications

    Page(s): 303 - 304
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    Freely Available from IEEE
  • Optical fibre transmission lines

    Page(s): 313 - 325
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1537 KB)  

    Optical fibre transmission lines have many advantages over coaxial cables. The most widely used fabrication techniques involve chemical vapour deposition resulting in losses of well below 1 dB/km. Analysis of propagation follows well-defined principles and the results obtained are broadly comparable with those at microwave frequencies, although the wavelength of operation, ¿1 ¿m, is much shorter. By suitable design single-mode fibres can be made to give bandwidth × length products approaching 100 GHz·km. Multimode fibres are now well understood, pose fewer problems and can be excited with light-emitting diodes. View full abstract»

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  • Some recent optical fibre developments. Part 1

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    Freely Available from IEEE
  • Optical fibre cables

    Page(s): 327 - 332
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (766 KB)  

    Optical fibre cables serve to protect the fibre sufficiently to allow installation of the cable without impairment of the transmission characteristics and to ensure fibre survival over the life of the cable. The degree of protection required is examined and some possible ways it may be achieved in practice discussed. View full abstract»

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  • Connectors for optical fibre systems

    Page(s): 333 - 340
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    This paper outlines the requirements of demountable connectors for optical fibres and cables used in data links and telecommunications applications. Problems associated with alignment and termination of the mating fibres are discussed. The various methods for overcoming or minimizing these problems are reviewed and specific examples of connector technology are highlighted. Some techniques for measuring the optical properties of connectors are given and their value and limitations in the assessment of system performance are detailed. Finally future requirements are discussed. View full abstract»

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  • Light-emitting diodes for optical fibre systems

    Page(s): 341 - 348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2273 KB)  

    Light-emitting diodes are important fibre optic sources not only for short haul, low cost data links, but also in the long haul, high data rate telecommunications field. This paper discusses the range of applicability of l.e.d. sources, and the performance, design and optimization of such devices. Results are given for devices operating both in the low-loss 1.3¿m window and in the 0.8¿0.9 ¿m window. View full abstract»

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  • Receivers for optical fibre communications

    Page(s): 349 - 361
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    This paper is a review of today's state-of-the-art in receivers for optical fibre communications, both in practice and in theory. The functions of an optical receiver are discussed, and a detailed description of unity-gain photodiodes is given. The problem of detection in the presence of noise is treated next, and the difference between optical and radio-frequency systems is highlighted. The theory of avalanche photodiodes is summarized, and state-of-the-art devices and their performance described. The final section is a review of the theory of optical receivers, with comparisons of theoretical predictions with practical achievements, especially for the sensitive p-i-n f.e.t. receivers. View full abstract»

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  • Semiconductor laser sources for optical communication

    Page(s): 362 - 376
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    The paper is a general review of double heterostructure GaAlAs and GaInAsP injection lasers and their application in long-distance optical communication systems. After briefly describing the physics of semiconductor laser operation, the performance of oxide stripe and advanced laser structures at 0.85, 1.3 and 1.55 ¿m wavelength is discussed. The parameters of greatest importance in optical communication systems such as laser spectrum and modulation response are covered in some detail and estimates of device parameters and manufacturing tolerances are given. The relative merits of the different types of laser for both multimode and single-mode optical fibre systems are then discussed. It is shown that single-mode systems operating close to the dispersion minimum are capable of data rates above 390 Mbit/s over distances of 30 km even when fairly conservative worst case assumptions are made. The key parameters that will allow single-mode systems to operate at data rates of more than 1 Gbit/s over distances of 50 to 100 km are identified. View full abstract»

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  • Systems applications of optical fibre transmission

    Page(s): 377 - 384
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    This paper describes a number of systems to demonstrate the wide application of fibre optic technology. It covers both undersea and landline trunk applications together with a discussion of power budgets and an indication of the benefits of long wavelength technology. Lower-speed digital systems for junction applications and avionics, military and industrial use are described as well as the transmission of analogue signals such as television. View full abstract»

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  • Characterization of single-mode optical fibres

    Page(s): 385 - 391
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    Experimental techniques for the measurement of total loss and absorption loss, chromatic and monochromatic bandwidth, mode cut-off and refractive index profile are reviewed and illustrated by the results obtained on a particular single-mode fibre. The relationship between theory and experiment is explored. View full abstract»

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  • Some recent optical developments. Part 2

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    Freely Available from IEEE
  • Optical fibre transmission systems¿the problems of formulating optical radiation safety criteria

    Page(s): 393 - 396
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (466 KB)  

    Although national and international standards regarding laser safety either already exist or are in the course of preparation, they do not specifically cover the use of lasers in optical fibre transmission systems. It is necessary to relate the safety requirements for lasers as published in the national and international standards to optical sources as used in optical fibre transmission systems. This paper attempts to do this and to stimulate discussion of the problems involved. The paper concludes that under normal operation optical fibre systems are intrinsically safe, since no exposure to optical radiation is possible. In cases where a fibre end is exposed, minimum viewing distances are proposed. View full abstract»

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  • Integrated optics: a tutorial review

    Page(s): 397 - 413
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    Integrated optics involves the use of thin transparent dielectric layers on planar substrates as optical waveguides. Various methods can be used to couple light into and out of the guiding layers, including butt and transverse coupling, prisms and diffraction gratings. Optical components are defined by photolithography, and may be passive (such as strip waveguides with bends, junctions and directional couplers) or active (such as switches, modulators and beam deflectors). The substrate and film materials may be glass for passive circuits, or electro-optic or semiconductor single crystal for active devices. Hybrid integration of active and passive devices may be used to produce complex integrated circuits. Alternatively, the use of semiconductor materials offers the possibility of monolithic integration of all types of component on a single substrate. View full abstract»

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