High sensitivity gas sensing method based on slow light in photonic crystal waveguide

This paper proposed a high sensitivity gas sensing system based on slow light in photonic crystal waveguide (PCW). The PCW was used as the gas chamber, and the harmonic detection method was adopted for signal processing. Combined the Maxwell equation with perturbation theory, the effective gas absorption factor was deduced which was greatly enhanced due to slow light in PCW. For the measurement of CO gas, a PCW was designed as the gas chamber and the detection sensitivity could be increased by 14.45 times compared with the traditional system that without PCW as the chamber. Thus the measuring detection limit of 21.5 ppm is achieved with active region is only 1 mm long. The proposed method provided a potential for expending the applications of slow light in the sensor fields, having powerful practicability and favorable application prospects.