128 × 128 silicon photonic MEMS switch package using glass interposer and pitch reducing fibre array
Citation
Hwang, H. Y., Morrissey, P., Lee, J. S., Brien, P. O., Henriksson, J., Wu, M. C. and Seok, T. J. (2017) '128 × 128 silicon photonic MEMS switch package using glass interposer and pitch reducing fibre array', 2017 19th Electronics Packaging Technology Conference, Singapore, 6-9 Dec. (4 pp). doi:10.1109/EPTC.2017.8277436
- Silicon Photonics
- Optical Packaging
- MEMS Switch
- Glass Interposer
- Through Glass Via (TGV)
- Pitch-Reducing Fiber Array
- Data Traffic Growth
- Scalability
- Row/Column Addressing
- Grating Couplers
- Ion-Exchanged Waveguide Array
Brief
This article presents the design and fabrication of a 128x128 silicon photonic MEMS switch package, utilizing a glass interposer and pitch-reducing fiber array for enhanced optical networking.
Summary
The article presents the design and fabrication of a packaging solution for a large-scale silicon photonic MEMS switch, aiming to address the growing demands of data traffic. The switch, featuring 128x128 ports (16,384 MEMS switch cells), leverages a row/column addressing scheme to reduce the number of electrical interconnects from 16,384 to 512. This reduction makes the design and implementation of electrical interconnections more manageable.
Here are some key aspects of the packaging solution:
- Electrical Packaging: A two-layer redistribution lines (2L-RDL) design on a through-glass via (TGV) interposer accommodates the 512 electrical interconnects. The interposer connects to the switch device on one side and a five-layer test board on the other.
- Optical Packaging: The switch employs 272 grating couplers for optical input and output. A pitch-reducing optical coupling array, utilizing ion-exchanged waveguides, addresses the challenge of the couplers' small pitch (63.5µm). This array gradually increases the waveguide pitch to 127µm for easier coupling with a standard fiber array.
- Planar Coupling Approach: A planar coupling approach is used for the optical interface, offering better packaging integrity compared to vertical coupling. To compensate for the shallow waveguide depth in this approach, an aluminum coating is applied to the coupling facet.
The article highlights the challenges encountered during the development process, such as the limited routing space due to optical coupling requirements and difficulties in achieving uniform insertion loss across the optical channels. While the testing and characterization of the complete package were ongoing at the time of publication, the article emphasizes the significance of this packaging solution as a step toward realizing high-density silicon photonic MEMS switches for future data center applications.