Fabrication of mid-infrared hollow-core Bragg fiber and it application in gas sensing
中红外空心Bragg光纤的制备及在气体传感中的应用

In its application of gas sensing,the transmission band of the hollow-core Bragg fiber should match the main absorption peak of the target gas.In this paper,we introduce the design method of the hollow-core Bragg fiber transrmssion band and develop a fabrication process supporting its transmission band control.Fiber samples with fundamental transmission bands at 10.6μm and 3.3μm are fabricated,whose transmission losses are 5.9 dB/m and 8.8 dB/m,respectively,measured by the cut-back method.Utilizing the fiber sample with a transmission band of 3.3μm,the injection and the expulsion of CH4/N2 gas are realized and observed by the change of fiber transmission spectrum.The detection limit of the experimental system is measured to be 26 ppm for CH4 by exponential dilution method,demonstrating the feasibility of hollow-core Bragg fiber in its application of gas sensing.