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

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THz electromagnetic radiation is used in a variety of fields including high-resolution imaging, wirelesscommunication, skin cancer screening, chemical analysis, etc. Typical THz sources have limitations ofcomplex setups or low temperature, etc. hindering size shrinking down and consequently, manypotential applications.Here we propose to use spintronics, or spin-electronics, to develop on-chip, DC powered THz sourceswith tuneable output frequency. The spintronic THz emitter is simple to fabricate with methodscompatible with industrial protocols, it works at room temperature, it is all-electrical, and it is scalabledown to the nanometre scale. Realising it would attract enormous interests for its potentialapplications.Here we give two examples:Wireless above 100 GHz: These devices could find applications for the development of high resolutionradars for automotive applications for driver's assistance (see through fog and rain) and trafficcoordination. 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 andnot allowing space resolution below ~ 1 mm. Having the possibility to bring the same analysis on-chipvia a cheap, all-electrical device that allows gaining several orders of magnitude in the achievablespace resolution would be an enormous gain.Ultra-fast computing: The past twenty years have seen an explosion of data exchange due to cloudcomputing, mobile connectivity and increasingly data-intensive technologies such as artificialintelligence and autonomous driving. The processing of this huge amount of data is putting a greatstrain on data centres and demands faster and more compact memories. The operating frequency ofthe devices together with their areal density is what determines computational power. While thesecond quantity steadily increased in the past decades, the clock speed has remained pinned at a fewGHz for the past twenty years. Having on-chip and CMOS-compatible THz sources would offer a way topush the working speed up by several orders of magnitude.