Thirty years ago Dyakonov and Shur opened a new field in solid-state physics and electronics - plasma-wave electronics. They theoretically predicted that: i) in nano-transistors, plasma waves may oscillate at THz frequencies far beyond the devices’ cut-off GHz frequencies, ii) THz radiation can be detected by plasma nonlinearities, and iii) the current flow can lead to the generation of THz radiation. The detection part of the “plasmonics promise” was proven and nowadays THz plasmonic detector arrays are widely used. In the case of emitters, the task turned out to be considerably more complicated. Only recently (PRX 10, 031004, 2020; with my team’s participation) room temperature, current-driven amplification of incoming THz radiation has been demonstrated in an innovative double grating gate structures based on graphene, one of the most promising materials for plasmonics. These break-through results indicate that existing models of plasmonic systems should be reconsidered and that using new 2D materials or their heterojunctions with innovative geometries, may lead “Towards on-chip plasmonics amplifiers of THz radiation”, which is TERAPLASM’s main objective. The experimental methodology will involve fabrication and THz spectroscopy studies of graphene and alternative-to-graphene unique HgTe and GaN-based systems with a high mobility 2D electron gas. This will allow finding the physical mechanisms responsible for the observed THz plasmonic amplification and select the optimum systems for THz devices. In parallel, theoretical research will develop physical models of THz plasmonic amplification studied in the experimental part of the project. By conducting extensive technological, spectroscopic, and theoretical research TERAPLASM will aim to answer the old basic physics and electronics questions on the feasibility of on-chip plasmonics amplifiers of THz radiation, with important potential applications in wireless telecommunication, biosensing, security, and others.

The primary objective of the original project is to develop a Chip-Scale Optical Atomic Clock (CSOC) using 1310nm and 1556nm light sources combined with 85Rb atomic transitions. With the addition of a new Widening Partner (WP) to the CSOC consortium, the project's scope gains a new dimension. The consortium now gains access to Gallium Nitride (GaN) based visible light emitters adding additional wavelength range from 390nm to 520nm, with a specific focus on integrating a 461nm laser diode into the CSOC photonic circuits. The introduction of the 461nm laser is significant as it aligns with the requirements of the 87Sr optical atomic clock, potentially enabling cross-utilization of technologies between different atomic clock platforms. Exploring the blue spectrum with a 461nm wavelength holds great promise for future optical atomic clocks, enhancing precision and advancing chip-scale optical components and photonics. Successful integration of GaN-based emitters and SiN waveguides into the CSOC project could also spark interest in various other applications, including telecommunications, optical sensing, and quantum technologies. The methodology involves two routes: hybrid-integration of separate GaN and SiN chips and hetero-integration of GaN chip onto SiN structure using transfer printing. By pursuing both integration pathways for GaN emitters and SiN chips in parallel, the project aims to maximize success within a tight timeframe while comprehensively assessing each approach's strengths and weaknesses. The impact of adding the WP includes enhanced expertise in GaN research, expanded capabilities for GaN-based device development, and access to valuable market insights. This collaboration also benefits students and researchers, strengthening the workforce in semiconductor and optoelectronic fields.

Optical atomic clocks are at the heart of modern technology. From time-keeping to navigation to global positioning systems. This project will develop the world’s first all optical atomic clock that is chip scale. It will create this based on recent advances in Kerr soliton micro-comb technology, ps mode locked lasers that are heterogeneously integrated on a chip, and using novel on chip frequency doublers with vastly improved efficiency. Exploiting the Rb85 two photon transition enables to obtain a clock signal that is vastly improved compared to today’s radio frequency transition based clocks. This clock can revolutionize timekeeping in both mobile, airborne or space application and used in future GPS networks such as Galileo. Moreover the underlying clockwork - a chipscale comb - can have applications ranging from distance measurements, to time and frequency metrology. This consortium brings together the leading groups in Europe in the domain of Frequency combs, micro-comb technology and photonic chipscale laser integration.

Lasers are ubiquitous in science and technology, with applications ranging from optical communications and quantum technologies to metrology and sensing and to life sciences and medical diagnostics. However, most commercially used lasers are still based on legacy optical schemes. These devices are either bulky and expensive limiting product development, or lack the ability to quickly sweep or precisely control the laser wavelength, which is key to many applications. At the same time, the advent of advanced photonic integration platforms such as silicon photonics has opened new perspectives, realized only for exascale data centers in telecommunication wavelengths around 1310 and 1550 nm. AgiLight aims at establishing a new class of integrated lasers that can address the entire wavelength range from the blue (400 nm) to the infrared (2.7 µm). These devices rely on a hybrid integration platform that combines ultra-low-loss silicon nitride photonic circuits with advanced tuning actuators and with III-V gain elements, exploiting highly scalable assembly concepts based on 3D printing. The devices will offer high output powers (> 100 mW), down to Hz-level laser linewidths, and unprecedented frequency agility with nanosecond response times and wideband tunability. Comprising leading European research groups and high-tech start-ups as well as a major industrial player, AgiLight will translate ground-breaking research to rapid technology uptake and tailor laser systems for atomic and molecular physics and optics, distance ranging and sensing using the expertise of end-users. The project covers the theoretical and nanofabrication foundations of the envisaged light sources as well as their implementation and functional demonstration in highly relevant research applications throughout the visible and near-infrared spectrum. AgiLight will lay the foundation for an all-European value chain of a novel class of light sources, covering the III-V and low-loss PICs.