Integrated silicon photonic MEMS

Abstract

Silicon photonics has emerged as a mature technology that is expected to play a key role in critical emerging applications, including very high data rate optical communications, distance sensing for autonomous vehicles, photonic-accelerated computing, and quantum information processing. The success of silicon photonics has been enabled by the unique combination of performance, high yield, and high-volume capacity that can only be achieved by standardizing manufacturing technology. Today, standardized silicon photonics technology platforms implemented by foundries provide access to optimized library components, including low-loss optical routing, fast modulation, continuous tuning, high-speed germanium photodiodes, and high-efficiency optical and electrical interfaces. However, silicon’s relatively weak electro-optic effects result in modulators with a significant footprint and thermo-optic tuning devices that require high power consumption, which are substantial impediments for very large-scale integration in silicon photonics. Microelectromechanical systems (MEMS) technology can enhance silicon photonics with building blocks that are compact, low-loss, broadband, fast and require very low power consumption. Here, we introduce a silicon photonic MEMS platform consisting of high-performance nano-opto-electromechanical devices fully integrated alongside standard silicon photonics foundry components, with wafer-level sealing for long-term reliability, flip-chip bonding to redistribution interposers, and fibre-array attachment for high port count optical and electrical interfacing. Our experimental demonstration of fundamental silicon photonic MEMS circuit elements, including power couplers, phase shifters and wavelength-division multiplexing devices using standardized technology lifts previous impediments to enable scaling to very large photonic integrated circuits for applications in telecommunications, neuromorphic computing, sensing, programmable photonics, and quantum computing.

Integrated 4-terminal single-contact nanoelectromechanical relays implemented in a silicon-on-insulator foundry process

“…To demonstrate that these issues can be overcome, we report for the first time, nanoscale, silicon (Si) 4-T NEM relays that are patterned in front-end-of-line (FEOL) processing and monolithically integrated with back-end-of-line (BEOL) metallic interconnect layers manufactured in a commercial silicon-on-insulator (SOI) foundry platform (iSiPP50G by IMEC 16–19 ). The foundry wafers containing the NEM relay structures and interconnects are post-processed to implement the electrical isolation between the control and signal paths of the 4-T NEM relays, the metallization of the contacts of the 4-T NEM relays, and the suspension of the movable sections of the relays.…”

“…To enable the realization of VLSI NEM relay-based logic circuits, integrated 4-T NEM relays have to be manufacturable using high-yield, foundry-compatible processes. We structured our 4-T NEM relays and interconnects in the commercial SOI foundry process iSiPP50G offered by IMEC 18 as depicted in Fig. 2a, with a subsequent post-foundry process as shown in Fig.…”

Evanescent coupling of nonlinear integrated cavities for all-optical reservoir computing

“…A common strategy for coherent signals is Mach-Zehnder interferometers with two phase shifters, typically based on the thermo-optic effect (TO). Such phase shifters require a constant supply of electrical current, and their state-of-the-art chip footprint is 109 × 21 µm [62]. If we were to estimate the neuron density of an RC with a readout, it would be limited to 200 neurons mm −2 .…”

“…However, such shifters do not suffer from thermal crosstalk, which would allow for a more compact design. They also require three orders of magnitude less power [62]. Phase shifters based on plasmonic nonlinear polymers are even more compact, with the device length being 29 µm [63].…”

Coherent free-electron light sources

“…Thus far, SPR has developed from near-UV [71] to X-rays [72] . With advancements in microand nanotechnologies, such as photolithography, electron beam exposure, and ion beam etching, grating structures with reduced spatial dimensions can be manufactured [73][74][75][76] , thereby permitting SPR radiation on some nonperiodic structures [77] . Electron beam emissions generated by field emitters/integrated all-silicon structure circuits have been reported in several studies [78,79] .…”