High-efficiency vertical fibre-to-polymer waveguide coupling scheme for scalable polymer photonic circuits

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Integrated Optics

Background:

• Polymer photonic circuits are valuable for communication, sensing, and optical signal processing due to their optical properties.
• Efficiently coupling optical fibers to polymer waveguides remains a significant challenge in the field.

Purpose of the Study:

• To propose and demonstrate a wafer-scale vertical coupling scheme for polymer waveguides.
• To address the limitations in optical fiber to polymer waveguide integration.

Main Methods:

• Utilized a silicon nitride grating coupler with an inverse taper.
• Integrated the coupler with SU8 polymer waveguides for vertical coupling.
• Performed detailed design, simulation, fabrication, and characterization.

Main Results:

• Achieved a maximum coupling efficiency of -3.55 dB in the C-band and -2.92 dB in the L-band.
• Demonstrated a 3-dB bandwidth of 74 nm in the C-band and 80 nm in the L-band.
• Validated the scheme's performance through comprehensive testing.

Conclusions:

• The proposed vertical coupling scheme offers a scalable and efficient surface grating solution.
• This approach facilitates the integration of polymer waveguides into photonic integrated circuits.
• The method enhances the practical application of polymer-based photonic devices.