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ALL-OPTIcal signal processing on-Chip in hybrid III-V/ Si integrated platforms

Final Report Summary - ALLOPTICS (ALL-OPTIcal signal processing on-Chip in hybrid III-V/ Si integrated platforms)

The project goal was to lay the foundations of an all-optical signal processing architecture that provides a novel on-chip technology for managing the transfer of information across the communication network. The cost, size, and energy requirements of the present electronic equipment that manages data flows are rapidly reaching crisis point, accelerated by the exponential growth of the global Internet traffic. A promising solution lies in moving to all-optical technologies, where optical data are handled without conversion into electrical signals; this would allow the inherent speed of light and its high data-handling capacity to be fully exploited in the core of the network. The construction of the underlying integrated nonlinear optical functions requires architectures and materials where the light-matter interaction is enhanced. Ideally, this technology should be CMOS compatible for ensuring the photonic-electronic convergence. While some progress has been achieved using silicon photonics, the power consumption, size and rapidity of the resulting devices are intrinsically constrained by the material and device geometry. ALLOPTICS aims at developing new solutions based on material platforms with less nonlinear loss than crystalline silicon in the Telecom band, and optimized slow light structures where light-matter interaction is promoted. Based on this new technology, ALLOPTICS targets the creation of low power and compact devices for regenerating and routing high-speed optical signals and more fundamental science goals that will prepare the groundwork for future research programs.

During the ALLOPTICS project ( advances have been made into the design of new slow light structures created into a semiconductor layer that are embedded into silica. These designs should be more robust than suspended membranes used so far, while enhancing the light-matter interaction for decreasing the power consumption of the resulting devices. They should allow for the creation of efficient nonlinear devices while improving heat dissipation, a critical issue for nonlinear applications.
We have experimentally identified a promising CMOS compatible platform, hydrogenated amorphous silicon, with the right combination of nonlinear properties in the Telecom band. Our measurements performed onto preliminary photonic crystal structures made in this material are promising but on-going fabrication optimization is required to reach the level of performance needed for applications. This platform should eventually sustain the creation of highly efficient nonlinear devices for all-optical signal processing and routing.
We exploited slow light enhanced nonlinear optics for the creation of highly compact and integrated optical auto-correlators that are capable of measuring short near-infrared pulses in the time-domain.
Finally, we developed a novel CMOS compatible SiGe-based platform for nonlinear optics in a spectral window that has been less explored, i.e. the mid-IR, but with many promising applications. We assessed the nonlinear properties of this platform, which should result in the creation of broadband optical sources with great implications for on-chip biosensing.