Developing on-chip, DC powered THz sources with tuneable output frequency for sensing and ultra-fast computing

THz electromagnetic radiation is used in a variety of fields including high-resolution imaging, wireless
communication, skin cancer screening, chemical analysis, etc. Typical THz sources have limitations of
complex setups or low temperature, etc. hindering size shrinking down and consequently, many
potential applications.
Here we propose to use spintronics, or spin-electronics, to develop on-chip, DC powered THz sources
with tuneable output frequency. The spintronic THz emitter is simple to fabricate with methods
compatible with industrial protocols, it works at room temperature, it is all-electrical, and it is scalable
down to the nanometre scale. Realising it would attract enormous interests for its potential
applications.
Here we give two examples:
Wireless above 100 GHz: These devices could find applications for the development of high resolution
radars for automotive applications for driver's assistance (see through fog and rain) and traffic
coordination. Existing commercial products reach as the radar transceivers by Silicon Radar
(https://siliconradar.com/) reach the sub-THz range (up to 300 GHz).
Chemical analysis: Many chemical elements have distinguished signatures at THz frequencies. So far,
contactless THz spectroscopy has mainly been used to study them, requiring expensive equipment and
not allowing space resolution below ~ 1 mm. Having the possibility to bring the same analysis on-chip
via a cheap, all-electrical device that allows gaining several orders of magnitude in the achievable
space resolution would be an enormous gain.
Ultra-fast computing: The past twenty years have seen an explosion of data exchange due to cloud
computing, mobile connectivity and increasingly data-intensive technologies such as artificial
intelligence and autonomous driving. The processing of this huge amount of data is putting a great
strain on data centres and demands faster and more compact memories. The operating frequency of
the devices together with their areal density is what determines computational power. While the
second quantity steadily increased in the past decades, the clock speed has remained pinned at a few
GHz for the past twenty years. Having on-chip and CMOS-compatible THz sources would offer a way to
push the working speed up by several orders of magnitude.

The impact of the CDT in Connected Electronic and Photonic Systems is expected to be wide ranging and include both scientific research and industry outcomes. In terms of academia, it is envisaged that there will be a growing range of research activity in this converged field in coming years, and so the research students should not only have opportunities to continue their work as research fellows, but also to increasingly find posts as academics and indeed in policy advice and consulting.

The main area of impact, however, is expected to be industrial manufacturing and service industries. Relevant industries will include those involved in all areas of Information and Communication Technologies (ICT), together with printing, consumer electronics, construction, infrastructure, defence, energy, engineering, security, medicine and indeed systems companies providing information systems, for example for the financial, retail and medical sectors. Such industries will be at the heart of the digital economy, energy, healthcare, security and manufacturing fields. These industries have huge markets, for example the global consumer electronics market is expected to reach $2.97 trillion in 2020. The photonics sector itself represents a huge enterprise. The global photonics market was $510B in 2013 and is expected to grow to $766 billion in 2020. The UK has the fifth largest manufacturing base in electronics in the world, with annual turnover of £78 billion and employing 800,000 people (TechUK 2016). The UK photonics industry is also world leading with annual turnover of over £10.5 billion, employing 70,000 people and showing sustained growth of 6% to 8% per year over the last three decades (Hansard, 25 January 2017 Col. 122WH). As well as involving large companies, such as Airbus, Leonardo and ARM, there are over 10,000 UK SMEs in the electronics and photonics manufacturing sector, according to Innovate UK. Evidence of the entrepreneurial culture that exists and the potential for benefit to the UK economy from establishing the CDT includes the founding of companies such as Smart Holograms, PervasID, Light Blue Optics, Zinwave, Eight19 and Photon Design by staff and our former PhD students. Indeed, over 20 companies have been spun out in the last 10 years from the groups proposing this CDT.

The success of these industries has depended upon the availability of highly skilled researchers to drive innovation and competitive edge. 70% of survey respondents in the Hennik Annual Manufacturing Report 2017 reported difficulty in recruiting suitably skilled workers. Contributing to meeting this acute need will be the primary impact of the CEPS CDT.

Centre research activities will contribute very strongly to research impact in the ICT area (Internet of Things (IoT), data centre interconnects, next generation access technologies, 5G+ network backhaul, converged photonic/electronic integration, quantum information processing etc), underpinning the Information and Communications Technologies (ICT) and Digital Economy themes and contributing strongly to the themes of Energy (low energy lighting, low energy large area photonic/electronics for e-posters and window shading, photovoltaics, energy efficient displays), Manufacturing the Future (integrated photonic and electronic circuits, smart materials processing with photonics, embedded intelligence and interconnects for Industry 4.0), Quantum Technologies (device and systems integration for quantum communications and information processing) Healthcare Technologies (optical coherence tomography, discrete and real time biosensing, personalised healthcare), Global Uncertainties and Living with Environmental Change (resilient converged communications, advanced sensing systems incorporating electronics with photonics).