A general design algorithm for low optical loss adiabatic connections in waveguides

• Published in: Optics express Vol. 20; no. 20; p. 22819
• Main Authors: Chen, Tong, Lee, Hansuek, Li, Jiang, Vahala, Kerry J.
• Format: Journal Article
• Language: English
• Published: United States 24.09.2012
• Subjects: Algorithms; Computer Simulation; Computer-Aided Design; Equipment Design; Equipment Failure Analysis; Light; Models, Theoretical; Optical Devices; Refractometry - instrumentation; Scattering, Radiation; Surface Plasmon Resonance - instrumentation
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.20.022819

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.