title: Low-loss silicon slot waveguides and couplers fabricated with optical lithography and atomic layer deposition.
abstract: We demonstrate low-loss silicon slot waveguides patterned with 248 nm deep-UV lithography and filled with atomic layer deposited aluminum oxide. Propagation losses less than 5 dB/cm are achieved with the waveguides. The devices are fabricated using low-temperature CMOS compatible processes. We also demonstrate simple, compact and efficient strip-to-slot waveguide couplers. With a coupler as short as 10 µm, coupling loss is less than 0.15 dB. The low-index and low-nonlinearity filling material allows nonlinearities nearly two orders of magnitude smaller than in silicon waveguides. Therefore, these waveguides are a good candidate for linear photonic devices on the silicon platform, and for distortion-free signal transmission channels between different parts of a silicon all-optical chip. The low-nonlinearity slot waveguides and robust couplers also facilitate a 50-fold local change of the waveguide nonlinearity within the chip by a simple mask design.
authors.affiliation: Aalto University, School of Electrical Engineering, Espoo, Finland. antti.saynatjoki@aalto.fi
authors.forename: A
authors.initials: A
authors.lastname: Säynätjoki
authors.forename: L
authors.initials: L
authors.lastname: Karvonen
authors.forename: T
authors.initials: T
authors.lastname: Alasaarela
authors.forename: X
authors.initials: X
authors.lastname: Tu
authors.forename: T Y
authors.initials: TY
authors.lastname: Liow
authors.forename: M
authors.initials: M
authors.lastname: Hiltunen
authors.forename: A
authors.initials: A
authors.lastname: Tervonen
authors.forename: G Q
authors.initials: GQ
authors.lastname: Lo
authors.forename: S
authors.initials: S
authors.lastname: Honkanen
mesh_terms: D017076:Computer-Aided Design; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis; D055096:Optical Devices; D010781:Photography / Q000379:methods; D012031:Refractometry / Q000295:instrumentation*; D012825:Silicon / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D012825:Silicon