Integrated silicon photonic packaging

Citation

Hwang, H. Y. (2019). Integrated silicon photonic packaging [Doctoral thesis, University College Cork]. https://hdl.handle.net/10468/9524

Keywords

• Silicon photonics
• Packaging
• Integration
• Optical assembly
• Electrical interposer
• Grating couplers
• Evanescent coupling
• MEMS optical switch

Brief

This thesis aims to bridge the gap between silicon photonics research and manufacturing by developing and demonstrating advanced packaging technologies, focusing on high-density integration and passive optical assembly.

Summary

The doctoral thesis, "Integrated silicon photonic packaging," by How Yuan Hwang (2019) explores advanced packaging technologies for silicon photonics, aiming to bridge the gap between device fabrication and final packaged products. The thesis emphasizes the need for high-density integration and efficient optical coupling methods to enable mass manufacturing of silicon photonic packages. Hwang uses state-of-the-art silicon photonic MEMS optical switches from the University of California, Berkeley as test devices to demonstrate the developed packaging solutions.

The thesis addresses the challenges posed by densely populated electrical and optical interconnects in silicon photonic devices. Two generations of packaging solutions are presented:

• First-generation packaging involves a 12x12 silicon photonic MEMS optical switch package using a ceramic interposer for electrical routing and a lidless fiber array for optical coupling. This approach demonstrates the feasibility of 2D packaging for silicon photonics.
• Second-generation packaging targets higher density integration with two test vehicles:

1. A pluggable package (Test Vehicle 2a) employs a ceramic interposer with spring-contacted interposers for electrical connectivity and enables decoupling of optical assembly.
2. A through-glass-via package (Test Vehicle 2b) utilizes a compact glass interposer with two metallization layers and through-vias, reducing electrical length and enabling 2.5D integration.

A key innovation is a 2D, 136-channel, pitch-reducing optical fiber array fabricated using ion-exchange processes, addressing the challenges of conventional fiber v-groove arrays. The thesis further investigates passive optical coupling methods:

• Grating-to-grating coupling, using vertically stacked gratings, eliminates active alignment, enables 2.5D integration, and offers cost savings by reducing active device size.
• Evanescent coupling based on buried glass waveguides integrated with through-glass-via interposers. This method simplifies the assembly process and reduces packaging complexity.

Hwang provides design rules and considerations for silicon photonic packaging, emphasizing the importance of device layout, material selection, and process compatibility. The thesis concludes that packaging plays a crucial role in realizing the full potential of silicon photonics, requiring innovative solutions and careful integration of electrical, optical, thermal, and mechanical aspects.

Origin: https://cora.ucc.ie/server/api/core/bitstreams/4c1b8595-1427-4514-bc2f-33c11056d833/content