High sensitivity temperature sensor based on a PDMS-assisted bow-shaped fiber structure

We experimentally demonstrate a bow-shaped fiber structure (BFS) fabricated by a simple knotting method. Interference transmission spectra of output light is observed due to interference between the core and cladding mode. The extinction ratio (ER) of output transmission spectra can be adjusted by pulling fiber pigtail of the BFS, which indicates the device can be applied to strain or displacement sensor. The temperature sensing performance is investigated with both bare and polydimethylsiloxane (PDMS)-assisted BFS. Compared with the bare structure, the sensitivity is extremely enhanced when the microfiber region is embedded in PDMS layer, which is as large as -1.63 nm/°C when temperature changing from 21.0 °C to 25.0 °C. The PDMS-assisted BFS with excellent characteristics of good mechanical stability, high sensitivity, low cost, easy fabrication and high flexibility is believed to have promising applications in the future.