DESIGN AND ANALYSIS OF COMPLETELY ADIABATIC TAPERED WAVE-GUIDES BY CONFORMAL MAPPING

In this study, we propose a novel equivalent-waveguide concept to desi gn the completely adiabatic tapered waveguides. The optimal combinatio n of taper shape and refractive-index distribution in such ideal struc tures is obtained by applying a series of conformal mappings to transf orm a single-mode straight waveguide into an equivalent tapered config uration. In an ideal taper the curved phase-front effect verifies the constant V-number concept is insufficient for designing a tapered wave guide. Also, the beam propagation method combined with the conformal m apping method is used to analyze the characteristics of light propagat ion in ideal structures. Simulation results predict that in the ideal taper a perfect mode-size conversion can be achieved adiabatically.