Distributed backscattering in production O-band Si nanophotonic waveguides

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Integrated Optics

Background:

• Backscattering in integrated photonic waveguides is a critical performance-limiting factor.
• Existing literature lacks extensive studies, especially on waveguides from production foundry processes.

Purpose of the Study:

• To experimentally measure and analyze distributed backscattering in production O-band silicon photonic waveguides.
• To identify the primary sources of backscattering in silicon and silicon nitride waveguides.

Main Methods:

• Experimental measurement of distributed backscattering.
• Analysis of backscattering trends across varying waveguide geometries and polarizations.
• Fabrication using production foundry processes.

Main Results:

• Measured backscattering ranged from -18 to -36 dB/mm in silicon waveguides.
• Sidewall stochastic defects were identified as the dominant source of backscattering in silicon.
• Both sidewall and cladding defects contribute to backscattering in silicon nitride waveguides.

Conclusions:

• Sidewall defects are the primary cause of backscattering in production silicon waveguides.
• Understanding these defects is crucial for improving optical system performance.
• Silicon nitride waveguides require consideration of both sidewall and cladding defects for accurate modeling.