The unprecedented maturity of silicon materials, processing, and device technologies, stemming from R&D investments now exceeding USD40B annually, clearly offers an enticing opportunity for leveraging into photonics applications and markets. Silicon-on-insulator (SOI) in particular provides many attractive design attributes for photonic circuits. Inherent physical benefits include a very high index contrast, enabling ultra-small bend radius index-guided circuits and devices[1], and a variety of high-performance photonic crystal concepts[2]. While silicon has historically not been viewed as a high-performance active optical material, recent work has now demonstrated that devices based upon plasma index mechanisms[3] can be quite efficient in field-effect configurations, effectively bypassing the previous bandwidth limitations of thermo-optic devices or forward-injection designs. Ge-based detectors, implemented with SiGe VLSI epitaxy technologies, have demonstrated high-performance waveguide designs, and recently even full silicon integrated photoreceivers at bandwidths as high as 17 Gb/s[4]. The result of these studies is a nearly full suite of active and passive photonics devices that can be implemented with very high density and yield using commercial CMOS foundry technologies, with well-documented low costs per unit wafer area. In addition to broad progress in the international research community, there has been significant recent acceleration enabled by DARPA's EPIC program[5,6], as well as impressive advances from start-up companies pursuing product development or deployments in concert with major silicon foundry partners.
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