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Bulk-Si platform: Born for DRAM, updated with on-chip lasers, and transplanted to LiDAR

Journal
IEEE Journal of Lightwave Technology
Date
2022.05.15
Abstract

The CMOS industry has been expecting silicon photonics to provide photonic and electro-photonic integrated circuits based on the CMOS processes and infrastructures for scalability of incumbent technology evolutions and creation of novel technologies. However, the compatibility with the legacy CMOS has been compromised with the development convenience of early silicon photonics in that the specialty silicon-on-insulator substrates have been widely used as integration platforms. Since this specialty substrate may hinder the photonics integration with legacy volume products later, a legacy-friendly integration platform with a generic bulk-silicon substrate has been developed for better compatibility. This paper overviews the bulk-silicon photonics platform born for DRAM integration, platform updates with III/V-on-bulk-Si lasers, and transplantation of its library to LiDAR applications where the virtuous cycle of cost-volume is on strong demand. The photonics integration with DRAM was to resolve the speed-capacity trade-off in the DRAM interconnects, and technical feasibility as well as lessons learned from the trial are reviewed. In the bulk-silicon device library in comparison to the silicon-on-insulator one, the thermal advantage of ~40% lower thermal impedance and the optical disadvantage of ~0.4 dB/mm higher waveguide losses are summarized. In the LiDAR applications, performances up to ~20m detection in 20fps by a single-chip scanner integrating tunable laser, semiconductor optical amplifiers, and optical phased array are presented with scalability analysis and future outlooks.

Reference
https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9695329
DOI
http://dx.doi.org/10.1109/JLT.2022.3146160