title: A general design algorithm for low optical loss adiabatic connections in waveguides.
abstract: Single-mode waveguide designs frequently support higher order transverse modes, usually as a consequence of process limitations such as lithography. In these systems, it is important to minimize coupling to higher-order modes so that the system nonetheless behaves single mode. We propose a variational approach to design adiabatic waveguide connections with minimal intermodal coupling. An application of this algorithm in designing the "S-bend" of a whispering-gallery spiral waveguide is demonstrated with approximately 0.05 dB insertion loss. Compared to other approaches, our algorithm requires less fabrication resolution and is able to minimize the transition loss over a broadband spectrum. The method can be applied to a wide range of turns and connections and has the advantage of handling connections with arbitrary boundary conditions.
authors.affiliation: TJ Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Tong
authors.initials: T
authors.lastname: Chen
authors.forename: Hansuek
authors.initials: H
authors.lastname: Lee
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Vahala
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008962:Models, Theoretical; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation*