Design and Characterization of Bio-Chemical Sensor Based on Photonic Crystal Fiber with Fluorine-Doped Tin Oxides Film

The Mid-infrared waveband plays an important role in the biochemical sensing and material analysis, while the silica glass fiber is rarely used in the mid-infrared region due to the high transmission loss, and most of the silica glass fiber sensors are only used for testing refractive index. In order to achieve both of the concentration and functional groups of biological sample simultaneously, in this paper, we proposed a dual-channel integrated photonic crystal fiber sensor with fluorine-doped tin oxide (FTO) based on the unique optical properties of photonic crystal fibers and FTO. The surface plasmon polaritons (SPP) of FTO in the mid-infrared region has high sensitivity to the refractive index of surrounding material. Theoretical result shows that the confinement loss of the proposed fiber can be close to zero realized by a kind of unique super mode. Meanwhile, it also has a good structural error-tolerant rate, which reduces the difficulty of preparation. These findings have potential to apply the mid-IR waveband to detect multiple physical quantities simultaneously in the biochemical sensing field.