Thin-Core-Fiber-Based Long-Period Fiber Grating for High-Sensitivity Refractive Index Measurement

作者：Fu Cailing; Zhong Xiaoyong; Liao Changrui^*; Wang Yiping; Wang Ying; Tang Jian; Liu Shen; Wang Qiao

来源：IEEE Photonics Journal, 2015, 7(6): 7103208.

DOI：10.1109/JPHOT.2015.2493721

• Long period fiber gratings
• thin core fiber
• fiber optics components
• fiber optics sensors

We experimentally demonstrated the fabrication of asymmetric long-period fiber gratings (LPFGs) in thin core fiber by use of focused CO2 laser beam. The proposed device exhibits a high extinction ratio of over 25 dB at the resonant wavelength and a narrowed 3-dB bandwidth of only 8.7 nm, which is nearly one order of magnitude smaller than that of LPFGs in conventional single-mode fibers. It also exhibits a high polarization-dependent loss of over 20 dB at resonant wavelength. The temperature and external refractive index (RI) sensitivity of the proposed structure are measured to be 46 pm/degrees C, within a temperature range from 25 degrees C to 100 degrees C, and 1047.3 nm/RIU, within the RI range from 1.400 to 1.440, respectively. The temperature induced error is similar to 8% for RI measurement. Such long LPFGs may find potential applications of highly sensitive RI sensors in the fields of chemical and biomedical sensing.

• 单位
  shenzhen univ