title: Impedance matching vertical optical waveguide couplers for dense high index contrast circuits.
abstract: We designed and demonstrated a compact, high-index contrast (HIC) vertical waveguide coupler for TE single mode operation with the lowest coupling loss of 0.20 dB +/- 0.05 dB at 1550 nm. Our vertical coupler consists of a pair of vertically overlapping inverse taper structures made of SOI and amorphous silicon. The vertical coupler can suppress power oscillation observed in regular directional couplers and guarantees vertical optical impedance matching with great tolerance for fabrication and refractive index variations of the waveguide materials. The coupler furthermore shows excellent broadband coupling efficiencies between 1460 nm and 1570 nm.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. rsun@mit.edu
authors.forename: Rong
authors.initials: R
authors.lastname: Sun
authors.forename: Mark
authors.initials: M
authors.lastname: Beals
authors.forename: Andrew
authors.initials: A
authors.lastname: Pomerene
authors.forename: Jing
authors.initials: J
authors.lastname: Cheng
authors.forename: Ching-Yin
authors.initials: CY
authors.lastname: Hong
authors.forename: Lionel
authors.initials: L
authors.lastname: Kimerling
authors.forename: Jurgen
authors.initials: J
authors.lastname: Michel
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods*; D012542:Scattering, Radiation