Flip-chip optical couplers with scalable I/O count for silicon photonics

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Semiconductor Device Fabrication

Background:

• Silicon photonics packaging is crucial for integrating optical components.
• Scalable and tolerant optical interfacing methods are needed for advanced photonic integrated circuits.
• Flip-chip bonding offers a promising approach for high-density interconnects.

Purpose of the Study:

• To develop and demonstrate a scalable and tolerant optical interfacing method for silicon photonics packaging using flip-chip bonding.
• To design and fabricate bidirectional optical couplers for efficient light transfer between silicon and polymer waveguides.
• To experimentally verify the performance of the developed optical interface across a relevant spectral window.

Main Methods:

• Design and fabrication of bidirectional optical couplers integrating silicon-on-insulator (SOI) and single-mode polymer waveguides.
• Utilizing flip-chip bonding as the core interfacing technique.
• Experimental characterization of coupling loss and misalignment loss within the 1530-1570 nm spectral range.

Main Results:

• Successful operation of the optical interface demonstrated in the 1530-1570 nm spectral window.
• Achieved coupling loss as low as 0.8 dB at 1570 nm for both polarization states.
• Planar misalignment loss below 0.6 dB (TE) and 0.3 dB (TM) for lateral offsets up to ± 2 µm.
• Observed no temperature dependence of coupling loss up to 70°C.

Conclusions:

• The developed flip-chip bonding method provides a scalable and tolerant solution for silicon photonics packaging.
• The bidirectional optical couplers exhibit high performance with low loss and robustness to misalignment and temperature variations.
• This interfacing technique is suitable for reliable optical interconnects in advanced silicon photonic devices.