Low-loss flexible Parylene photonic waveguides for optical implants

Area of Science:

• Materials Science
• Optoelectronics
• Biomedical Engineering

Background:

• Photonic waveguides are crucial for optical communication and sensing.
• Flexible, biocompatible materials are needed for implantable photonic devices.
• Parylene C offers promising properties but faces challenges with propagation loss.

Purpose of the Study:

• To develop low-loss photonic waveguides using Parylene C on a flexible, biocompatible platform.
• To identify and mitigate the sources of propagation loss in Parylene C waveguides.
• To assess the suitability of these waveguides for implantable applications.

Main Methods:

• Fabrication of Parylene C photonic waveguides using a novel conformal coating process.
• Characterization of waveguide propagation loss, focusing on sidewall roughness.
• Investigation of thermal annealing effects on waveguide performance.

Main Results:

• Achieved compact, low-loss (<5 dB/cm) Parylene C photonic waveguides.
• Identified reactive ion etching-induced sidewall roughness as the primary loss contributor.
• Reduced propagation loss by over 30 dB/cm through the new fabrication method.
• Thermal annealing at 300°C negatively impacted waveguide performance.

Conclusions:

• A new fabrication technique significantly enhances Parylene C photonic waveguides for implantable use.
• The developed waveguides offer a promising solution for biocompatible, flexible photonic integration.
• Further optimization is needed, as thermal annealing proved detrimental.