Optimum design of a planar array of tapered waveguides

The paper is concerned with the problem of designing a planar array with nearly ideal radiation characteristics. An array of tapered waveguides is used, and each input Bloch mode is adiabatically transformed into a plane wave. The array then radiates most of its power in the Brillouin zone Ω of order m = 0. It can be useful for a variety of applications, including star couplers and wavelength multiplexers suitable for lightwave distribution in local area networks. A design procedure for optimizing the array is described, and optimum design conditions and optimum efficiency are explicitly derived.