Near-infrared gas spectroscopy based on plasmonic photodetector applied for multiple gas species

We proposed a NIR spectroscopy system that measures multiple types of gases using a plasmonic photodetector. We formed a gold diffraction grating on a silicon substrate to create a plasmonic photodetector and conducted gas spectral measurements in the NIR region. As a result, we could measure the transmission spectrum of water vapor gas at a concentration of 2%. Furthermore, we could measure ethanol gas transmittance at different concentrations of 4.5% and 2.7%, and change in transmission depending on concentration. Lastly, the transmission spectrum of 10% NH3 gas was measured. Since these results are consistent with evaluations using Fourier transform IR spectroscopy, it was confirmed that the proposed gas measurement can be applied to multiple types of gas sensing.