ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

General Ideas of Optical Fibers

Updated on June 6, 2013

The transmission of light via a dielectric waveguide was first proposed and investigated at the beginning of the twentieth century. However, a transparent dielectric rod, typically of silica glass with a refractive index of around1.5, surrounded by air, proved to be an impractical waveguide due to its unsupported structure. Proposals for a clad dielectric rod was made in the mid 1950s inorder to overcome these problems. This structure is illustrated down below.

  1. Core
  2. Cladding
  3. Buffer
  4. Jacket

The figure shows a transparent core with a refractive index n1 surrounded by a transparent cladding of slightly lower refractive index n2. The cladding supports the waveguide structure and substantially reduces the radiation loss into the surrounding air. In essence, the light energy travels in both the core and cladding allowing the associated fields to decay to a negligible value at the cladding-air interface.

The invention of clad waveguide structure led to the first serious proposals by Kao and Hockham in 1966 to utilize optical fibers as a communication medium, even though they had losses in excess of 1000 dB km-1. These proposals stimulated tremendous efforts to reduce the attenuation by purification of the materials. This has resulted in improved conventional glass refining techniques giving fibers with losses of around 4.2 dB km-1. Progress in glass refining processes such as depositing vapor phase reagents to form silica has allowed fibers with losses well below 0.1 dB km-1 to be fabricated.

Most of this work was focused on the 0.8 - 0.9 micrometer wavelength band because the first generation optical sources fabricated from gallium aluminium arsenide alloys operated in this region. However, as silica fibers were studied in further detail it became apparent that transmission at longer wavelengths would result in lower losses and reduced signal dispersion. This produced a shift in optical fiber source and detector technology in order to provide operation at these longer wavelengths. Hence at longer wavelengths, especially around 1.55 micrometers, fibers with losses as low as 0.01 dB km-1 have been reported.

In order to appreciate the transmission mechanism of optical fibers with dimensions approximating to those of a human hair, it is necessary to consider the optical wave guiding of a cylindrical glass fiber. Such a fiber act as an open optical waveguide, which may be analyzed utilizing simple ray theory. However the concept of geometric optics are not sufficient when considering all types of optical fibers, and electromagnetic mode theory must be used to give a complete picture.

Types of Fiber Materials

Glass Fibers

A broad distinction may be made between glasses based on pure SiO2 and those derived from low softeing point glasses such as the sodium borosilicates, sodium calcium silicates and lead silicates. For convenience, we shall refer to this as silica fibers and glass fibers respectively. An obvious requirement of the material used is that it must be possible to vary the refractive index. Pure silica has a refractive index of 1.45 at 1 micrometer. B2O3 can be used to lower the refractive index, whilst other additives such as GeO2 raise it. Thus a typical fiber might consist of an SiO2 : GeO2 core with a pure SiO2 cladding. Glass fibers can be made with a relatively wide range of refractive indices, but control of the impurity content is more difficult than with silica.

Plastic Fibers

Other types of fibers are possible using plastics. For example, fibers are available with silica cores and plastic cladding. This plastic coated silica (PCS) fibers are easy to manufacture; the fiber core may simply be drawn through a bath of a suitable polymer which is subsequently cured by heating to a higher temperature to provide a solid cladding. This process readily lends itself to the production of step index fibers with large core diameters where very little of the energy is carried in the cladding. Such fibers are attractive for medium distance, moderate bandwidth communication systems where cost is a major consideration. Typical losses are in the order of 10 dB km-1 .

Fiber Optic Communication

Communications using an optical carrier wave guided along a glass fiber has a number of extremely attractive features, several of which were apparent when the technique was originally conceived. Optical fiber communication has following merits.

  1. Enormous potential bandwidth
  2. Small size and weight
  3. Electrical isolation
  4. Immunity to interference and cross talk
  5. Signal security
  6. Low transmission losses
  7. Ruggedness and flexibility
  8. System reliability and ease of maintenance
  9. Potential low cost


    0 of 8192 characters used
    Post Comment
    • jabelufiroz profile imageAUTHOR


      6 years ago from India

      Thank you rileriki.

    • rileriki profile image

      Mateja Ristic 

      6 years ago from New York

      Useful article for brief introduction of fiber optic cables.

    • roysyas profile image

      closed profile 

      6 years ago from Earth

      vote up for this impressive explanation.

    • carolina muscle profile image

      carolina muscle 

      6 years ago from Charlotte, North Carolina

      A interesting explanation of optical fiber technology. thank you!

    • Coolpapa profile image


      6 years ago from Florida

      Good piece on a component of communications that is taken for granted.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)