Periodic Reporting for period 1 - TERAOPTICS (Terahertz Photonics for Communications, Space, Security, Radio-Astronomy, and Material Science) Reporting period: 2020-09-01 to 2022-08-31 Summary of the context and overall objectives of the project The European Training Network (ETN) TERAOPTICS - Terahertz Photonics for Communications, Space, Security, Radio-Astronomy, and Material Science trains a new generation of creative, innovative and entrepreneurial early-stage researchers (ESR) in the field of THz Photonics.Terahertz (THz) radiation is the part of the electromagnetic spectrum between infrared and microwaves, meaning it is longer in wavelength than the former and higher in frequency than the latter. It is generally defined as the frequency range of 0.3 to 3 THz – or 300 to 3000 GHz. This part of the electromagnetic spectrum is not only notoriously hard to generate and detect, but also attracted a considerable interest in recent years, owing to potential applications in high-bandwidth and high-data-rate THz communications, satellite-to-satellite wireless links, THz spectroscopy for discovering star building in radio astronomy, high-resolution imaging and localization for security and in general for non-destructive material characterization and identification. These are not just high-impact scientific topics, but with the ever increasing interconnectivity of future industry and healthcare applications, beyond 5G technology such as THz communication put this field of research at the centre of enabling technologies for growth in virtually all sectors of the economy. Because of very recent scientific breakthroughs such as photonics mediated generation of ultra-low phase noise THz signal generation (see also Nobel prize 2005 in physics for Hänsch et al.), THz Photonics is seen as a key enabling technology (KET) for a variety of applications. With the increasing desire in recent years to achieve a higher degree of technological independence, TERAOPTICS plays a crucial part in the training of future Engineers and Scientists to develop such technologies. The main challenges for a commercial market breakthrough for THz technologies are widely considered to be the following: High output power over a large frequency range, reduction of noise in transmitter and receiver, compact and lightweight designs, and the capabilities to shape or form the beam as desired for the application. More specifically research-wise, the project aims to exploit the fundamental scientific knowledge of the breakthroughs to develop photonic mediated semiconductor-based THz sources, THz mixers, and THz detectors and integrated functional receivers and transmitters for future mobile THz systems in the targeted application fields. This means, that all the above challenges are addresses with integrated photonics, such as lasers interoperating on a single chip, are addressed. To achieve the goals all parts of the technological development process are addressed within the project: From the design of optical chips including advanced features such as novel laser sources and beam-forming networks to the packaging of the chips to make usable components out of them. This enables our researchers to transform new ideas, groundbreaking research and advanced technologies into innovative THz products and services for a sustainable economic and social development in the targeted application areas: communications, space, security, radio-astronomy and material science. TERAOPTICS raises excellence in THz Photonics by integrating a structured research program and doctoral training. The network extends the traditional academic research setting by incorporating open and inter-disciplinary research elements in an international and inter-sectorial network environment consisting of solely renowned, highly experienced and equipped academic and non-academic beneficiaries in the field of Terahertz Photonics (4 universities, 2 research institutes, 3 SMEs, and 2 industry) and 13 academic and non-academic partners. TERAOPTICS enhances the career perspectives of the ESRs through international, interdisciplinary, and inter-sectorial mobility combined with an innovation-oriented mindset.Therefore, the overarching objective of TERAOPTICS is to provide high-level training in the field of THz Photonics to a new generation of high achieving early-stage researchers, to provide them an inspiring research program and intellectual, scientific, technical and transferable skills trainings to enhance their career opportunities in academia and industry and to create the new generation of excellent, creative and risk-taking researchers and engineers. This goal will be achieved by a unique, internationally renowned, interdisciplinary, and inter-sectorial network of academic and non-academic beneficiaries and partners providing both formal (workshop-style) and informal (hands-on) research training in a most stimulating professional environment and non-academic placements and scientific conferences. Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far Since the beginning of the network, TERAOPTICS performed multiple high-level trainings, mentioned as one of the objectives, which are not only exclusively available to the ESRs within the network, but is also available to other young researchers from across Europe and the whole world, with over a hundred researchers who have already benefited from a participation in a TERAOPTICS training event within the first two years of the programme. These trainings focus on fundamentals in THz science and technology, just as well as on additional career aspects relevant to young researchers, such as high-impact publishing. The large visibility of these stand-alone events, just as well as the prominent display of TERAOPTICS at international conferences allowed for a wide dissemination within the scientific community already. Additionally, the youtube video lecture and social media channels achieve an audience past the direct scientific community.Scientifically, the first phase of the project focused on the design of the new concepts researched in TERAOPTICS. And now that our Early Stage Researchers are in place and finished their fundamental trainings, they succeeded with the fabrication of their initial components, so that the Europe-wide testing started. To make the most of the vast and diverse capabilities within the TERAOPTICS network, the ESRs travel through Europe to partner institutions for thorough testing and complimentary measurement campaigns. This will lead to the next step, where the ESRs combine their developed components for application testing. Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far) TERAOPTICs succeeded in the demonstration of multiple THz emitter concepts, comparison between different concepts, and already successfully demonstrated communication with said devices. This shows the balanced approach that the TERAOPTICS network is taking, by utilizing the diverse strengths within the network to pursue multiple approaches simultaneously to achieve the best results for the specific application. These components are accompanied by the first demonstrations of ultra-low-noise laser sources and power combining, which push the limits of what has been previously available for THz technology. Micrograph of a TERAOPTICS photonics chip during characterisation. View of the setup of the chip shown in the micrograph.