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Fibre optic cables
BOOKS Optical Fibers: materials and fabrication T Izawa, S. Sudo D.Reidel,1987,ISBN9&277-2378-8,ppx+186,E59.OO,US $79.00
glasses, even though, as the authors admit, they are not used for telecom fibres. A description of the transmission characteristics of silica fibres is at about the right level, though it suffers from the lackof definitions earlier. That on other fibre types is so brief it is hardly worth including.
With the maturity of silica libre technology a book on the materials aspects of fibres and their fabrication is long overdue. The authors are well placed to tackle this task since they have worked for many years at the forefront of libre development at N’IT Laboratories in Japan. The result, however, is disappointing.
In summary, this booklacks both balance and direction. It contains a lot of useful information, but the reader will be hard stretched to assess the relevance of much of it. Finally, one cannot help but wonder at the curious English which reaches its peak in the opening sentence of chapter six: ‘The transmission characteristics of various tibres will be described by the transmission loss characteristics.’
Aside from poor English, which should have been improved at the editorial stage, the booklacks a well defined direction and uniformity of treatment of the subject. Extreme attention to detail of the one process with which the authors are familiar is at the expense of adequate coverage of other, equally relevant, topics. An even bigger criticism is the apparent failure of the authors to identify clearly the nature of their readership. To those expert in the subject most of the content will be familiar; those less familiar will be inhibited by a lack of context and failure to define terms. There is for example, no adequate description of the structure of an optical tibre and important terms such as singlemode are left undefined. The book opens with a brief summary of the materials that have been used in optical tibres, including polymers and glasses for long wavelength transmission. There is a discussion of the optical loss mechanisms in glasses, but no attempt to explain how these determine either the minimum loss or the operating wavelength windows in silica tibres. The second chapter deals in more detail with the optical properties of pure and doped silica. Again, whilst all the topics are adequately covered from the physics viewpoint there is little attempt to place their relevance in context. The two main chapters on fibre fabrication techniques illustrate the lack ofbalance. Whilst over 50 pages are devoted to an in-depth treatment of the vapour axial deposition (VAD) process, the alternative, and more widely used outside vapour deposition (OVD) and modified chemical vapour deposition (MCVD) are covered along with libre pulling in 23 pages. Too little attention is given to the chemistry of the OVD and MCVD processes. The section on fibre pulling lacks a detailed discussion of coatings; indeed ultra-violet curable coatings which are now becoming the industry standard are not even mentioned. The discussion of the VAD process leaves no aspect of the subject uncovered. One feels at times that the authors are desperate to include every known fact, and at times the chapter reads more like a research report than a review. Soot consolidation alone is afforded more space than tibre pulling and coating, for example. For the reader who wishes to acquire a detailed understanding of the process variables of the technique this chapter would be invaluable; the majority, however, who want an overview of tibre fabrication would find it overwhelming. The last two chapters are again somewhat superficial. There is a brief summary of multicomponent glasses which includes non-silica glasses. Somewhat surprisingly there is detailed discussion of the purification of such
322
M.G. Scott Si?L Fibre Optic Cables G. Mahlke, I? G&sing
John Wiley, 1987, ISBN O-471-91409-6, pp 253, g25.00 The authors of this book attempt to explain the theory and practice of tibre optics, from the first principles of Snell’s law to the practical considerations of installing a fibreoptics network in a real industrial environment. After two pages of history, the book starts with brief reviews of the physics and chemistry of optical libres, and the merits of different refractive index profiles. Chapter 5, the first containing any substantial details, describes the major parameters of the different fibres available (such as attenuation and dispersion) and the techniques of measurement. This is followed by brief chapters on optical fibre construction, manufacture and fibre buffers, bringing us to the two chapters forming the heart and main purpose of the book. The first details the different mechanical requirements of optical cables and the different constructions currently available. Chapter 10 deals with installation problems and practices - splicing, connectors and the like. The book finishes with brief chapters on network topologies, optical transmitters and receivers, couplers and optical systems, plus an excellent glossary. This is not a book for beginners with little or no knowledge of optics. Its emphasis is primarily and intentionally on the practical, engineering aspects of the subject. As such, chapters outside this area are very brief, and this is the only criticism of an otherwise excellent book. For example, Chapter 3, on the chemistry of glass lasts just six pages ofA paper, plus the periodic table. Similarly, the previous chapter on the physics of optical waveguides could usefully be expanded to explain modes and modal interference more clearly. What this book does is give an excellent overview for an engineer,moving into this new area from a related discipline. The text is illustrated with numerous diagrams of exceptional clarity and many worked examples. G. Tebby
Optronics
OPTICS AND LASER TECHNOLOGY
glasses, even though, as the authors admit, they are not used for telecom fibres. A description of the transmission characteristics of silica fibres is at about the right level, though it suffers from the lackof definitions earlier. That on other fibre types is so brief it is hardly worth including.
With the maturity of silica libre technology a book on the materials aspects of fibres and their fabrication is long overdue. The authors are well placed to tackle this task since they have worked for many years at the forefront of libre development at N’IT Laboratories in Japan. The result, however, is disappointing.
In summary, this booklacks both balance and direction. It contains a lot of useful information, but the reader will be hard stretched to assess the relevance of much of it. Finally, one cannot help but wonder at the curious English which reaches its peak in the opening sentence of chapter six: ‘The transmission characteristics of various tibres will be described by the transmission loss characteristics.’
Aside from poor English, which should have been improved at the editorial stage, the booklacks a well defined direction and uniformity of treatment of the subject. Extreme attention to detail of the one process with which the authors are familiar is at the expense of adequate coverage of other, equally relevant, topics. An even bigger criticism is the apparent failure of the authors to identify clearly the nature of their readership. To those expert in the subject most of the content will be familiar; those less familiar will be inhibited by a lack of context and failure to define terms. There is for example, no adequate description of the structure of an optical tibre and important terms such as singlemode are left undefined. The book opens with a brief summary of the materials that have been used in optical tibres, including polymers and glasses for long wavelength transmission. There is a discussion of the optical loss mechanisms in glasses, but no attempt to explain how these determine either the minimum loss or the operating wavelength windows in silica tibres. The second chapter deals in more detail with the optical properties of pure and doped silica. Again, whilst all the topics are adequately covered from the physics viewpoint there is little attempt to place their relevance in context. The two main chapters on fibre fabrication techniques illustrate the lack ofbalance. Whilst over 50 pages are devoted to an in-depth treatment of the vapour axial deposition (VAD) process, the alternative, and more widely used outside vapour deposition (OVD) and modified chemical vapour deposition (MCVD) are covered along with libre pulling in 23 pages. Too little attention is given to the chemistry of the OVD and MCVD processes. The section on fibre pulling lacks a detailed discussion of coatings; indeed ultra-violet curable coatings which are now becoming the industry standard are not even mentioned. The discussion of the VAD process leaves no aspect of the subject uncovered. One feels at times that the authors are desperate to include every known fact, and at times the chapter reads more like a research report than a review. Soot consolidation alone is afforded more space than tibre pulling and coating, for example. For the reader who wishes to acquire a detailed understanding of the process variables of the technique this chapter would be invaluable; the majority, however, who want an overview of tibre fabrication would find it overwhelming. The last two chapters are again somewhat superficial. There is a brief summary of multicomponent glasses which includes non-silica glasses. Somewhat surprisingly there is detailed discussion of the purification of such
322
M.G. Scott Si?L Fibre Optic Cables G. Mahlke, I? G&sing
John Wiley, 1987, ISBN O-471-91409-6, pp 253, g25.00 The authors of this book attempt to explain the theory and practice of tibre optics, from the first principles of Snell’s law to the practical considerations of installing a fibreoptics network in a real industrial environment. After two pages of history, the book starts with brief reviews of the physics and chemistry of optical libres, and the merits of different refractive index profiles. Chapter 5, the first containing any substantial details, describes the major parameters of the different fibres available (such as attenuation and dispersion) and the techniques of measurement. This is followed by brief chapters on optical fibre construction, manufacture and fibre buffers, bringing us to the two chapters forming the heart and main purpose of the book. The first details the different mechanical requirements of optical cables and the different constructions currently available. Chapter 10 deals with installation problems and practices - splicing, connectors and the like. The book finishes with brief chapters on network topologies, optical transmitters and receivers, couplers and optical systems, plus an excellent glossary. This is not a book for beginners with little or no knowledge of optics. Its emphasis is primarily and intentionally on the practical, engineering aspects of the subject. As such, chapters outside this area are very brief, and this is the only criticism of an otherwise excellent book. For example, Chapter 3, on the chemistry of glass lasts just six pages ofA paper, plus the periodic table. Similarly, the previous chapter on the physics of optical waveguides could usefully be expanded to explain modes and modal interference more clearly. What this book does is give an excellent overview for an engineer,moving into this new area from a related discipline. The text is illustrated with numerous diagrams of exceptional clarity and many worked examples. G. Tebby
Optronics
OPTICS AND LASER TECHNOLOGY