ABSTRACT
This chapter provides a description of optical coupling in single-mode (SM) fiber systems using Gaussian beam approximation. An essential factor in the implementation of an optical transmission system is the interconnection of the various components such as transmitters, fiber-optic transmission lines, repeaters, and receivers. The coupling of SM fibers by splicing or by means of optical connectors has been given extensive treatment. Treatment will also be given to techniques which are frequently employed to improve efficiency and reduce optical feedback. The optimum coupling efficiency can be obtained for identical field distribution of source and the fundamental mode of the fiber. The effect of "near" reflections from the fiber face and from coupling lenses on the laser emission characteristics is described with the Compound Cavity Model. The fiber front ends are carefully cleaved and placed in position, usually in the case of SM fibers, by observing and optimizing the amount of coupled light.
