What happens when two lasers are sent in counterpropagating directions through a medium? Surprisingly, this question has only attracted limited attention in the past. However, the nonlinear interaction of counterpropagating light in resonators has fascinating implications. One effect that we recently discovered is the spontaneous symmetry breaking and optically induced nonreciprocity of counter-propagating optical modes. This symmetry breaking manifests itself in a remarkable effect: light of the same frequency and power can enter a microresonator in one direction but not in the other. The fundamental nature of such a broken symmetry could impact science far beyond optical physics. This proposal aims to exploit this discovery for novel types of photonic elements. Work package (A) addresses an urgently needed photonic element: the integrated optical diode (or isolator). Currently, such devices rely on magneto-optical effects that make it impossible to integrate them into chip-based photonic circuits. The use of Kerr-nonlinearity induced symmetry breaking in a simple microring resonator is a promising route towards a novel class of nonreciprocal integrated optical devices. Work package (B) addresses research on nonlinear-enhanced optical gyroscopes. Currently the best gyroscopes are based on ring lasers that cannot be further miniaturized because their sensitivity scales with their size. The symmetry breaking of counter-propagating light in a microresonator has the potential to overcome this limitation and to realize microphotonic gyroscopes with unprecedented sensitivities. The final work package (C) will investigate the nonlinear interaction of counter-propagating light for optical switching and optical memories. We believe that this proposal on optical nonreciprocity and spontaneous symmetry breaking of counterpropagating light will lead to a variety of fascinating developments both in fundamental science and for the next generation of integrated photonic devices.

The EU Green Deal sets ambitious targets for the transformation towards a climate neutral continent. Hydrogen plays a key role as an energy in this ambition, yet the metrological infrastructure to support the entire hydrogen supply chain is underdeveloped. This project will focus on key aspects of determining quality and quantity of hydrogen, monitoring and regulatory conformity, providing the necessary measurement standards, methods, models and best practices for the production, storage, transmission, and distribution of hydrogen

Complex wireless technologies underpin the internet of things, and fifth and sixth generation (5G and 6G) mobile networks. These ‘new radio’ technologies require improved underpinning documentary wireless standards for the radio signals, systems, transmission environments used, and the radio frequency exposures created. Current challenges faced by the telecommunications sector include a lack of accurate, fast, lowcost, and traceable methods for manufacturers to demonstrate 5G/6G product verifications match customer specifications. This project aims to develop the practical and efficient measurement methods required to enable normative standards to better match rapidly emerging radio technologies for 5G/6G product and system over-the-air testing, for wireless channels up to sub-THz, and for radio frequency exposure assessment.

Battery and automotive industries face strong competition for high capacity energy storage technologies for use in electric vehicles, portable devices and grid stabilisation. Despite recent advances in battery performance, capacities and lifetimes are still too poor for many key applications. To accelerate innovation by materials and device manufacturers, new metrology is urgently required. This project supports the development of operando techniques, underpinned by standardised ex situ analysis and electrochemical measurements, to enable beyond state-of-the-art battery materials characterisation.

The conformity assessment of biomethane requires further standardisation in order to support Europe’s green energy future. The overall EU target for Renewable Energy Sources consumption by 2030 has been raised to 32 % in the RED II directive [Directive (EU) 2018/2001, 2018]. This project will deliver accessible traceability to the stakeholder community by developing efficient and effective methods for the preparation of traceable gas transfer standards for the performance evaluation of biomethane monitoring systems. Using these, a robust performance assessment protocol will be developed and validated in order to benchmark and characterise analytical systems (e. g. gas analysers). The outputs, including trial applications, will be directly fed into standardisation development. This project will bridge the gap between previously developed primary standards and the industry’s need for accessible, traceable performance evaluation against a validated protocol.