CMOS compatible Photonic integrated circuits(PICs) are becoming increasingly popular in cuttingedge applications, such as optical interconnects, signal processors for quantum and microwave photonics, on-chip sensing and so forth due to low cost, high volume production and scalability. Low loss waveguides with tightly confined guided mode is the key for designing such large-scale PICs using CMOS fabrication process technology. Besides high refractive index Si waveguide core, SiN waveguides are also gaining major attention due to its relatively lower waveguide losses, wider transparency, less sensitivity to temperature fluctuations and fabrication variations,etc. However, elements such as modulators and phase shifters are difficult to realize in SiN due to the difficulty in tuning the refractive index of the host material, while Si devices can be easily tuned using the thermo-optic or the plasma-dispersion effect. Thus integration of SiN with 220-nm SoI (Silicon on Insulator) platform can offer benefits that can significantly expand the existing portfolio of Si photonic technologies. However, there are few technological challenges to be solved for efficient hybrid integration of SiN waveguide devices.



In this talk, first we are going to discuss the different methodologies adopted by major research institutes and commercial foundries for demonstration of functional PICs with hybrid Si/SiN waveguides. And thereafter, some progress made in this direction using our in-house fabrication facilities will be discussed.