Dr Alberto Rodríguez Cuevas - Aston University

The stand-off detection of hazardous substances, particularly explosives, remains a critical yet technically challenging objective in security and defence. Explosives exhibit exceptionally low vapour pressures, often in the parts-per-trillion to parts-per-billion range, making their detection in the gas phase considerably more demanding than for typical chemical warfare agents or environmental pollutants. Furthermore, concealed explosives release only trace volatile organic compounds (VOCs) into the atmosphere, requiring highly sensitive and selective detection technologies capable of operating at safe distances.  

This project proposes the development of a dual-comb spectroscopy (DCS) platform for the stand-off detection of hazardous materials, leveraging two complementary optical frequency comb (OFC) sources already developed at Aston University. One is a fibre-based, polarization-multiplexed dual-comb system; the other employs electro-optic modulators (EOMs) seeded at 1550 nanometres. Both systems will be evaluated and benchmarked for their ability to detect trace VOC emissions associated with explosive materials under realistic conditions, including interference from complex chemical backgrounds.  

Building upon this foundation, the project will extend DCS operation into the 2-micrometre spectral window by integrating a thulium-doped seed laser and amplifier into the EOM-based system. This extension targets stronger molecular absorption features critical for enhancing sensitivity. A multi pass optical configuration will further boost detection limits by increasing the optical interaction path length. Real-world validation will involve the detection of both VOC emissions and direct spectroscopic signatures from concealed hazardous substances.  

The approach prioritises remote detection aligned with operational needs in border control, critical infrastructure protection, and urban security. By combining broadband coverage, high resolution, rapid acquisition, and portable implementation, this project aims to bridge the gap between laboratory OFC systems and field-deployable chemical threat detectors, offering a significant advancement in national security sensing capabilities.