Phonon-based Circuits: Towards New Energy Efficient Information Technologies

Harnessing the potential of combined phononics, photonics and radiofrequency electronic signals to reduce the carbon footprint of information and communication technology


In our knowledge-based society, Information and Communications Technologies (ICT) are a cornerstone of everyday life. As the world becomes more digitally reliant, innovation in ICT necessarily develops at tremendous speed. But while these advancements benefit humankind in so many ways, there is also a downside: With many ICT devices already commonplace, and with the uptake of IoT tools forecast to increase exponentially, their energy consumption teeters on the verge of becoming unsustainable.


The issue was addressed by the recently concluded Horizon 2020 project PHENOMEN (watch a video introducing the research). Funded by the EU Future and Emerging Technologies (FET) programme, the consortium investigated how power consumption of these technologies could be reduced based on lower energy carriers of information known as phonons.


Currently, most information is transported by electrical charge – electrons, and by light – photons, which can incur high energy consumption. While electrons and photons are relatively common concepts, phonons – units of vibrational energy that arise from a lattice of atoms uniformly oscillating at a single frequency – are less widely known.


In future, these circuits will complement the existing silicon technology and could be applicable in such areas as the IoT and local (edge) information processing.


PHENOMEN will exploit the use of phonons in information technology. Part of their plan is to build phonon lasers which be run using cavity opto-mechanics. One of their research challenges however is to make sure that they are processing phonon signals at room temperature, as these are often the case only picked up at a higher temperature. Once this issue has been resolved, these will be part of the in-chip signal which can perform signal processing actions (such as signal generation, guiding, filtering, demultiplexing and detection) at room temperature.


While silicon-on-insulator photonics offers a versatile platform for the development of integrated optomechanical circuits one constraint is the high costs. Thus, research combined this technology with materials compatible with silicon-based ICT systems, for instance nanocrystalline silicon, which is significantly more cost efficient. In future, these circuits will complement the existing silicon technology and could be applicable in such areas as the IoT and local (edge) information processing.

Schematics of the PHENOMEN project Technology Platform showing the on-chip integration of piezoelectric, phononic and photonic components. The interdigitated transducer (IDT) are the electrical input to and output from the phononic circuit. Inset: Scanning electron micrograph of the IDTs, the optomechanical nanobeam and the optical waveguide realized in crystaline and nanocrystalline silicon. The device includes aluminium nitride (AlN) as the piezoelectric material and the IDTs are made out aluminium (Al). (Courtesy of Prof A. Martinez and of Mr. M. Colombano Soza).


The project produced several noteworthy outcomes, such as the development of a series of different components including detectors and processing elements. In addition, within the information processing circuit, the researchers achieved synchronisation of two sources, leading to the emission of coherent phonons – ‘coherent’ referring to the atomic motions which occur when an atom receives an impulsive external force that enables it to move at the same pace as its neighbouring atoms. This achievement led to a decrease in noise, which is a promising step towards addressing a remaining challenge.


“In the long term, the impact PHEMONEN could have on the electronics industry is huge,” said project coordinator Clivia Sotomayor Torres from Spain’s Catalan Institute of Nanoscience and Nanotechnology. “The unique value of phonon-based information processing circuits is the prospect of low energy information processing and the demonstrated integration onto a silicon platform thus ensuring reproducibility, upscaling, and cost efficiency. This technology has real potential to become a key element of information processing in the smart IoT autonomous concept.”


While the technology generated still requires 10 to 20 years of work before it can enter the market, by the end of the project in February 2020 the consortium had already produced 20 scientific publications – with more in the pipeline – and a series of prototypes. In addition, a spinoff is in the works: one project partner has teamed up with a company for a patent application; together they are preparing an exploitation plan as part of the new FET Innovation Launchpad project SIOMO. Three further patent applications are also pending as a result of PHENOMEN, and additional proposals have been submitted by project partners to continue the research.


Background information

FET-Open and FET Proactive are now part of the Enhanced European Innovation Council (EIC) Pilot (specifically the Pathfinder), the new home for deep-tech research and innovation in Horizon 2020, the EU funding programme for research and innovation.


Cover photo: Photo by Christina @ on Unsplash