In Situ Multiphysical Metrology for Photonic Wire Bonding by Two-Photon Polymerization.

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Femtosecond laser two-photon polymerization (TPP) is crucial for micro/nano optical devices, especially photonic wire bonding (PWB) for optical interconnects.
• Optimizing optical loss and reliability of polymeric photonic wires remains challenging due to inadequate multiphysical metrology.
• Current methods struggle to meet the demands for practical, in-situ, multiphysical measurements.

Purpose of the Study:

• To develop and apply novel in situ scanning electron microscopy (SEM) for multiphysical metrology of TPP-fabricated PWBs.
• To evaluate the production quality and understand multiphysical coupling effects in microscale polymeric waveguides.
• To optimize PWB design for improved optical loss and mechanical reliability in optical interconnects.

Main Methods:

• Utilized in situ scanning electron microscopy (SEM) for real-time monitoring of working PWBs.
• Performed simultaneous optical and mechanical measurements on microscale photonic wires.
• Analyzed the relationship between structural parameters (curvature, cross-section) and material failure modes.

Main Results:

• Photonic wires with larger local curvature radii exhibited plastic failure, while smaller radii showed elastic recovery.
• Increased cross-sectional dimensions significantly improved mechanical robustness.
• Optical loss in elastically deformed wires was temporary and recoverable upon load removal.
• Optimized PWBs achieved a minimum insertion loss of 0.6 dB.

Conclusions:

• In situ SEM metrology provides a novel approach for multiphysical analysis of PWBs.
• Understanding multiphysical coupling is key to optimizing microscale polymeric waveguide design.
• This approach can enhance the mass production reliability of TPP technology for chip-level optical interconnections.