Abstract

There is currently considerable interest in novel ARROW^[1-5] waveguide structures. One prospect in view is the creation of novel linear and nonlinear couplers. The ARROW couplers have a finite number of layers whereas true BRAGG waveguides have an infinite number. Nevertheless, they are quite easy to relate to each other. This paper addresses the difficult problem of structures such as ribs, used for twodimensional confinement. The problem with such structures is that it is very difficult to make any analytical progress and any that is made is usually based upon some form of effective index method or a restricted coupled mode theory. Such a method can sometimes work well even for rib waveguides, provided the system is not close to cutoff. If several ribs are put together, as they would be in an ARROW or an ARROW coupler, then it is clear that the finite element method has a strong synergism with the structure under investigation.

© 1992 IQEC