AN ALL-FIBER GAS SENSING SYSTEM USING HOLLOW-CORE PHOTONIC BANDGAP FIBER AS GAS CELL

摘要

An all-fiber compact gas sensing system using a hollow-core photonic bandgap fiber (HC-PBF) as a gas cell is proposed in this paper. Compared with the present reported microstructured optical-fiber gas cells, the HC-PBF gas cell proposed here has relatively lower transmission loss and much simpler construction. The total transmission loss through the HC-PBF gas cell is demonstrated experimentally to be as low as 1.5 dB and the time taken for gas to get into the 90-cm-cell, under the free diffusion condition, is approximately 11 min. Combining the HC-PBF gas cell with a tunable fiber laser, an all-fiber gas sensing system is developed. The properties of the proposed system are demonstrated experimentally by detection of carbon monoxide (CO) and acetylene (C_(2)H_(2)). Approximately linear relationships between the system responses and the concentrations of the detected gases are experimentally demonstrated. The minimal detectable concentration of CO of 300ppm and C_(2)H_(2) of 5 ppm are also achieved respectively by the experiments.