Tunable Diode Laser Plasmonic Grating Spectroscopy for Hydrogen Sensing

The design and development of portable plasmonic embedded measurement systems represents a significant engineering challenge, aimed at delivering the high sensitivities observed in devices based on such physical phenomena to field applications. This work proposes the Tunable Diode Laser Plasmonic Grating Spectroscopy technique to achieve a system architecture in which narrower resonances observed in metallic diffraction gratings enable the spectral detection of analytes. The primary application investigated is hydrogen sensing using Palladium (Pd) and Niobium (Nb) hydride-forming structures. Analytical and numerical simulations are employed to assess the influence of hydrogen gas presence on the metal dielectric function and structural parameters. It is demonstrated that highly linear detection can be achieved using spectral detection systems, and in the case of a Nb grating on a flexible substrate, a theoretical 55 ppm limit of detection is attainable.