Abstract
An in-fiber Mach–Zehnder interferometer (MZI) is proposed and experimentally demonstrated for relative humidity (RH) and temperature measurements. The MZI is formed by a grapefruit-shaped photonic crystal fiber (G-PCF) cascaded with a short section of multimode fiber that serves as a mode coupler. To enhance sensitivity to humidity, femtosecond laser micromachining was performed to remove a portion of cladding of the G-PCF to expose its core to the ambient medium. The output interference spectrum is fast Fourier transformed to produce a spatial frequency spectrum that describes the intensity composition of the cladding modes in the MZI. In our investigation, it was observed that the interference dip intensity has a sensitivity of to the change of RH in the range of 25%–80% RH, whereas the dip wavelength has a temperature sensitivity of in the range of 25°C–70°C. In addition, the dip intensity was insensitive to temperature. These characteristics have provided convenience in eliminating temperature cross talk and achieving accurate humidity measurement.
© 2018 Optical Society of America
Full Article | PDF ArticleMore Like This
Yimei Zhong, Zhengrong Tong, Weihua Zhang, Juan Qin, and Wenlin Gao
Appl. Opt. 58(29) 7981-7986 (2019)
Ce Bian, Manli Hu, Ruohui Wang, Tingting Gang, Rongxin Tong, Lisong Zhang, Teng Guo, Xiaobo Liu, and Xueguang Qiao
Appl. Opt. 57(2) 356-361 (2018)
Lei Liang, Hao Sun, Nan Liu, Hao Luo, Tingting Gang, Qiangzhou Rong, Xueguang Qiao, and Manli Hu
Appl. Opt. 57(4) 872-876 (2018)