Large-scale parallel optical interconnects hold the key to resolving the grand challenge of enormous bandwidth requirement between on-chip cores and within multi-chip modules. Silicon photonics, which is the mostly available integrated photonic platform, must excel in energy efficiency and bandwidth density in order to meet the stringent requirement of future extreme-scale photonic interconnects. The goal of this GOALI proposal is to develop hybrid silicon-transparent conductive oxide (Si-TCO) devices, especially microring resonators including microdisks, with unprecedented electro-optic (E-O) tunability and energy efficiency for large-scale on-chip wavelength division multiplexing (WDM) optical interconnects. The proposed research is highly interdisciplinary and will impact academia, industry, and photonics community by proving a unique path to integrate highly efficient TCO materials with silicon photonics. If successful, this GOALI project will lay a solid foundation toward developing a new type of silicon photonic devices for future extreme-scale on-chip WDM optical communication. The education and outreach activities will benefit graduate, undergraduate and K-12 students, and broaden the participation of under-represented minorities and women students at OSU. This research will also promote industrial collaboration with Hewlett Packard Enterprise and AIM Photonics, and broaden the research experiences of students in science and engineering at Oregon State University (OSU).
TCO materials have attracted escalating research interests in integrated photonic devices, metamaterials and metasurfaces in recent years due to the extraordinary refractive index tuning achieved either through oxygen vacancy doping or electrical gating. In addition, TCO materials can be deposited with high quality using DC- or RF-sputtering on various platforms, which also possess long-term stability. Therefore, TCO materials are fully compatible with silicon photonics and has the potential to be readily integrated with existing silicon photonic integrated circuits (PICs). This GOALI project will focus on the development of metal-oxide-semiconductor (MOS) capacitor-driven active silicon-TCO photonic devices as well as exploring the feasibility of scalable integration with existing silicon photonic platforms. The main objectives of this research include: 1) demonstrating hybrid Si-TCO micro-ring filters with extremely large E-O tuning efficiency to compensate fabrication errors and temperature variation without any thermal heater; 2) implementing an athermal on-chip 4-channel WDM transmitter module using dual-functional microring resonators, which can simultaneously function as wavelength tunable filters and high speed E-O modulators; and 3) verifying process compatibility and hybrid integration with silicon photonics for future scalable manufacturing using AIM Photonics foundry service. We expect that the electrically tunable silicon microring resonators with near-zero wavelength tuning power will replace the power-hungry thermal heaters that have been used for decades. Most importantly, we will prove that such scalable MOS-driven photonic devices can be fabricated by combining AIM Photonics passive silicon-on-insulator multi-project wafer (SOI-MPW) runs and in-house TCO processes at OSU.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
