Special issue paper. Transmission and mechanical properties of protected optical fibres for use in optical-fibre cables

The transmission characteristics of various types of fibres, fibre strengthening, cabling and cable techniques such as joint and fault location are discussed. The basic approaches used to obtain experimental results are indicated together with the inherent problems associated with optical fibres. The transmission characteristics of the fibres being investigated such as those of the plastic cladding, annular, conventional step index and graded index types are discussed. The strengthening of individual fibres for fibre breakage prevention and the undesirable effects of subsequent cabling processes on optical properties are discussed. The basic approach to fibre buffering for the preservation of optical properties is described with a method for protecting fibres. The mechanical properties of the cables for underground and indoor use are discussed, and the test equipment and test results are explained. The optical properties of the fibres in the cable have been proved to be virtually unchanged by careful design of the cables. The detectability of the breaking conditions of fibres by a pulse-echo technique is discussed. V-groove splicing is shown with its associated experimental results.