Temperature characteristics of hetero-core optical fiber Au/TiO2 SPR sensors fabricated by sputtering and Layer-by-Layer stacking techniques

In this paper, we proposed hetero-core optical fiber temperature sensors with an Au and TiO2 multilayer film formed by the sputtering and Layer-by-Layer (LbL) stacking technique. A TiO2 is known as a material with a relatively large temperature coefficient of refractive index. In our previous work, a hetero-core fiber optic temperature sensor based on surface Plasmon resonance (SPR) utilizing the Au and TiO2 formed by the sputtering has been proposed, which could measure the temperature less than 50 °C. The sensitivity of the temperature sensor improves with increasing thickness of the TiO2 film formed on the optical fiber. In order to improve the deposition rate of the TiO2 thin film, we tried to form the TiO2 film by the LbL technique. We experimentally confirmed that the sensitivities in the optical loss change of the hetero-core fiber SPR sensor with the Au/TiO2 multilayer film made by the sputtering and by the LbL method were 1.5 × 10-3 dB/°C and 2.9 × 10-3 dB/°C with ranging from 100 to 300 °C at the wavelength of 900 nm and 850 nm, respectively.