Graphene for high-speed communications

The Photonics and Optoelectronic Work Package focuses on research areas and high technology readiness level (TRL) activities that provide fast solutions for data-transmission, image sensing technologies and terahertz (THz) detection at room temperature, which are difficult to achieve with traditional electronic and optical technologies. 

The last 10 years 

As graphene has evolved from components to application-tailored prototypes over the past decade, the objectives of the Work Package have followed the same trajectory. We launched five spin-offs (i.e., Camgraphic, Emberion, Cambridge Raman Imaging and Qurv) stemming from the research and development efforts of the Work Package. These meet the needs of different industries, and target optical sensors, imaging systems and data communications. 

In particular, Cambridge Raman Imaging is developing a coherent Raman microscopy platform, based on the graphene-enabled dual wavelength fibre laser source, that can differentiate between cancer and healthy tissues. Preliminary chemometric data of tumour tissue samples have been acquired and the product is expected to be launched as soon as the end of 2023, targeting the market of cellular process analysis in academia and pharma/biotech industry. Then the product will evolve into a clinical scanner to assess tissue biopsies and support histopathologists in the process of diagnosing cancer. 

During Core 3, some of the activities with higher TRL moved to the Graphene Flagship Spearhead Projects linked to data communication and broadband image sensors. In the Work Package, we aim to develop the best performing building blocks, while the work carried out in the Spearheads focuses on engineering innovative solutions. By the end of 2023, we aim to surpass state-of-the-art devices and target end-user specifications with the motivation to advance the TRL of these systems even further in the future. 

This year’s progress 

Over the past year, the researchers in the Photonics and Optoelectronic Work Package worked on THz lasers and detectors. They produced a THz quantum cascade laser (QCL) working at 55% of its total possible range of frequencies. This ability, known as "comb operation", is useful for detecting harmful gases and explosives and can be applied to infrared imaging systems to detect medical conditions, breath analysers and a variety of other sensing and spectroscopic applications. 

The team also reported room temperature detectors for THz frequencies using CVD-grown, large-area, single-layer graphene, integrated in antenna-coupled field effect transistors. The device showed quick responses (around 5 nanoseconds) and low levels of background noise. 

Finally, the scientists discovered a way to generate a photovoltage perpendicular to the usual electron flow by shining circularly polarized light on a bilayer graphene device. This new energy source can be used for detecting small amounts of light and energy, which could have important applications in fields like infrared and terahertz sensing, space imaging, medical imaging and material inspection for security purposes. 

References 

Riccardi, E. et al. Laser Photonics Rev. 2022, DOI: 10.1002/lpor.202200412 

Di Gaspare, A. et al. Adv. Opt. Mater. 2022, DOI: 10.1002/adom.202200819 

Asgari, M. et al. Appl. Phys. Lett. 2022, DOI:  https://aip.scitation.org/doi/full/10.1063/5.0097726