Sensitive carbon monoxide detection based on laser absorption spectroscopy with hollow-core antiresonant fiber

A carbon monoxide (CO) sensing system based on hollow-core antiresonant fiber (HC-ARF) is developed using tunable diode laser absorption spectroscopy (TDLAS) technology. A HC-ARF with length of 75 cm is applied as light transmission passage and gas chamber. Compared with conventional multipass cell, HC-ARF has the advantages of compact volume, low cost, steady transmission, and simple optical alignment. Two techniques of direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) were used respectively. In DAS, the minimum detection limit (MDL) was 12251.04 ppm. In WMS, the modulation depth of this HC-ARF based CO-TDLAS sensor was optimized to be 0.13 cm(-1) and the R-squared numeric of the linear relationship between the peak of the 2 f signal and the gas concentration was 0.99, indicating that the system has a nice linear responsiveness to the CO gas concentration. Finally, the MDL of the sensor was calculated to be 196.33 ppm.