Near-Infrared Spectroscopic Gas Detection Using a Surface Plasmon Resonance Photodetector with 20 nm Resolution

Abstract

This paper reports on gas sensing based on near-infrared (NIR) reconstructive spectroscopy using a surface plasmon resonance (SPR) photodetector. The reconstructive spectrometer consists of an Au grating structure on an n-type silicon substrate. When the Au grating is irradiated with transverse magnetic polarized light, SPR emerges at different incident angles for each wavelength, producing an electric current via the Schottky barrier at the Au/n-type Si interface. The irradiated light spectrum can be derived by analyzing the relationship between the incident angle and the current. The proposed reconstructive spectrometer presented a 20 nm wavelength resolution in the NIR region. NIR light absorption appeared at approximately 1392 nm in the 1.5% ethanol gas spectrum by the SPR photodetector, which is coherent with Fourier transform infrared spectroscopy, indicating that the proposed reconstructive spectrometer is applicable to gas measurements.

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

“…1, which is almost the same as the one reported in Ref. 25. The gas sensing principle and procedure are as follows.…”

“…On the other hand, the measurable gas concentration is estimated to remain at a few ppm levels with low resolution by noise analysis. 25) In the latest research, some methods measure ammonia or ozone in the atmosphere with high resolution at the ppb level using tunable lasers for spectroscopic gas measurement. 35,36) Bridging this resolution gap will be a requirement in the future.…”

“…23) In response to this problem, our group has proposed a NIR spectroscopic method using a gold diffraction grating plasmonic photodetector as an IR spectroscopy method that does not require an optical path length. [24][25][26] This photodetector can excite surface plasmon resonance through a diffraction grating formed on a silicon substrate. Due to surface plasmon resonance, free electrons in gold are excited, and by having these free electrons flow into the silicon substrate, it has the function of measuring the surface plasmon resonance as an electric current.…”

“…24,26) However, at present, gas sensing by NIR spectroscopy using this plasmonic photodetector is limited only to the measurement of specific concentrations of ethanol gas, and the changes in response when measuring different concentrations and the adaptability to other gas measurements have not been verified. 25) Therefore, an additional evaluation of whether the sensor can be deployed for other types of gases has not been made. In this study, we verified the possibility of deploying NIR gas sensing by spectroscopy to measure water vapor, ethanol gas at different concentrations, and NH 3 gas.…”

High-Performance Waveguide-Integrated Ge/Si Avalanche Photodetector with Lateral Multiplication Region

“…Near-infrared photodetectors have been widely used in fiber communication [ 1 , 2 , 3 , 4 , 5 ], spectroscopy [ 6 , 7 ], and light detection and ranging (LIDAR) [ 8 , 9 ]. High-speed and high-sensitivity photodetectors are desirable to relax the power budget and improve the energy efficiency of fiber communication.…”