Silicon nitride CMOS-compatible platform for integrated photonics applications at visible wavelengths

Area of Science:

• Materials Science
• Photonics
• Nanotechnology

Background:

• Integrated photonic circuits are crucial for optical communication and sensing.
• Silicon nitride (SiN) is a promising material for photonic applications due to its optical properties.
• Developing cost-effective and high-performance SiN-based devices is an active area of research.

Purpose of the Study:

• To demonstrate silicon nitride as a high-performance, cost-effective material for dense integrated photonic circuits in the visible spectrum.
• To report experimental results for nanophotonic waveguides and key photonic components.
• To characterize the performance of these components for practical applications.

Main Methods:

• Fabrication of nanophotonic waveguides using a standard CMOS pilot line.
• Characterization of waveguide losses in aqueous and silicon dioxide cladded environments.
• Design and testing of waveguide bends, grating couplers, and multimode interference couplers (MMI) at 660 nm.
• Optimization of buried oxide layer thickness for grating coupler efficiency.

Main Results:

• Waveguide losses below 0.71 dB/cm in aqueous environments and 0.51 dB/cm with silicon dioxide cladding.
• High integration densities enabled by high index contrast, with insertion losses below 0.05 dB per 90° bend for radii as small as 35 µm.
• Grating couplers achieved efficiencies above 38% for TE polarization through optimized buried oxide layer design.

Conclusions:

• Silicon nitride is a viable and efficient material for fabricating integrated photonic circuits in the visible spectrum.
• The demonstrated components and low losses pave the way for advanced photonic applications.
• The use of a standard CMOS process line suggests a cost-effective manufacturing approach for these photonic circuits.