ANALYSIS OF THE COUPLING CHARACTERISTICS OF A TAPERED 3-GUIDE COUPLED SYSTEM

Optical coupling characteristics of a three-guide coupled system are discussed. Application of a taper-formed waveguide in the system is proposed. We carried out the theoretical analysis of the new tapered waveguide system by applying a modified coupled-mode theory, with the tapered guide being approximated by a successive stepped small guide segments. Based on numerical examinations, novel coupling characteristics of the tapered guide system, compared with a conventional uniform system, are demonstrated. A symmetrical coupled-guide structure is shown to be suitable for composing three-branched optical power dividers and power combiners, with a relaxed restriction on the guide coupling length. Taper slope and waveguide separation are two important parameters for designing power dividing ratios. Application of the tapered three-guide coupled system in a new type of optical isolator is also proposed. We present the main working principles of the new isolator. © 1990 IEEE