SiN half-etch horizontal slot waveguides for integrated photonics: numerical modeling, fabrication, and characterization of passive components.

This work presents a "half-etch" horizontal slot waveguide design based on SiN, where only the upper SiN layer is etched to form a strip that confines the mode laterally. The numerical modeling, fabrication, and characterization of passive waveguiding components are described. This novel slot waveguide structure was designed with on-chip light amplification in mind, for example with an Er-doped oxide spacer layer. Proof-of-concept racetrack resonators were fabricated and characterized, showing quality factors up to 50,000 at critical coupling and residual losses of 4 dB/cm at wavelengths away from the N-H bond absorption peak in SiN, demonstrating the high potential of these horizontal slot waveguides for use in active integrated photonics.