Final Report Summary - NOLIMITS (NOvel Large-scale InP-Membrane based Integration Technology & Science) Today’s information society relies on huge data centers to process and transfer massive amounts of data that grow every month. Both the current Internet and the Internet of Things (IoT) are growing rapidly. Computer clusters with the size of warehouses are used, where the interconnection of individual processors is limiting the total system performance. This “interconnect bottleneck” can only be overcome by employing optical interconnects. Nanophotonic technologies, as explored in the NOLIMITS projects, hold a promise for a large increase in energy efficiency because of the tight integration of photonics and electronics which allows for short interconnections with low resistance and capacitance, and for compact and energy efficient sources and detectors. The latter is also important for the IoT, where low-power operation is crucial to support autonomous sensors powered by energy harvesting.In the ERC research program NOLIMITS we have developed a new optical technology to achieve these goals. The technology enables integration of the full photonic functionality in a sub-micron-thick Indium-Phosphide-layer on top of a conventional CMOS electronics chip. The use of a thin photonic membrane results in compact photonic components with high speed and low power consumption. The tight interconnection of electronic and optical components allows versatile chip design and further improves space and energy efficiency. A generic design approach based on a set of well-tested fundamental building blocks brought us a robust and cost-effective nanophotonic platform for R&D purposes.Over the past four years, the NOLIMITS team has achieved significant progress towards realization of a versatile nanophotonic technology platform. • Light sources: Efficient amplifiers and lasers are demonstrated in an InP membrane on silicon. A novel design enables reduced footprint and full integration with PIN detectors and passive devices in a single membrane layer. We also realized waveguide-integrated nano-LED light sources with feature size of only 300 nm. They show record-high waveguide-coupling efficiency and promising dynamic performance.• Detector: We demonstrated a uni-travelling carrier (UTC) based detector with record-wide electrical bandwidth (beyond 67 GHz) among state-of-the-art detectors realized in membranes. It was tested in novel optical wireless receivers, and record-high wireless data transmission has been demonstrated.• Modulator: A novel electro-absorption modulator (EAM) concept based on the band-filling effect has been proposed and analyzed. A record-wide optical bandwidth is predicted for these novel EAMs. This property is especially crucial for wavelength-division multiplexing (WDM) technology for optical interconnects.• Technologies: In the project we developed a number of enabling technologies, including wafer-scale bonding, ultra-smooth dry etch, low-loss metal contacts and highly efficient surface treatment. These technologies have attracted significant international interest from academic and industrial groups.This project has initiated a unique research line on membrane-based nanophotonics, which can address many societal challenges (including interconnection and beyond). We ensure the continuity of this promising research line through active cooperation with other projects.
