Gas Detection by Near-Infrared Spectroscopy Based on a Surface Plasmon Resonance Photodetector

This paper reports a gas detection method by near-infrared (NIR) spectroscopy using a Surface Plasmon Resonance photodetector (SPR) equipped with an Au grating on a n-Si substrate. The photodetector can detect light of a specific wavelength as photocurrent at a corresponding incident angle. The spectrum of incident light can be obtained from the photocurrent by examining the responsivity of each wavelength of the photodetector in advance. we fabricated the photodetector and measured the absorption spectrum of ethanol gas in the NIR laser using the photodetector, and absorption around λ = 1390 nm was observed.