▎ 摘　　要

To improve the selectivity of carbon nanotubes for gas sensors, we design a surface plasmon polarization waveguide based on graphene that can sense trace gases. In addition, a gas concentration measurement system was designed for a sensor based on optical cavity ring-down spectroscopy. The gas concentration measurement system was composed of two loops, which were combined with the minimum mean square error algorithm to achieve an amplified spontaneous emission noise filter. The experimental results show that the gas concentration measurement error was significantly improved after CO filtering. The slope of the logarithmic ring-down curve and the ring-down time decreased with the increasing gas concentration. The gas concentration and ring-down time showed an improved linear relationship. The design system can detect trace gases as a single gas or a variety of toxic gases in special environments. The device provided a wide range of sensors and measurements. Moreover, the proposed device is relatively simple and easy to implement, with high detection sensitivity. (C) 2019 Elsevier Ltd. All rights reserved.