Modulation of the sensing bandwidth of dual-channel SPR sensors by TiO2 film.

• This work utilizes TiO 2 film to tune the sensing bandwidth and the resonance wavelength range to the near-infrared band. • A dual-channel sensor with wide bandwidth is proposed. • The experimental results show that the RI range of the sensor is 1.333–1.385, and the temperature range is 10–80 ℃. • The sensor has simple structure and good repeatability. Facing the diversity and complexity of the types of parameters to be measured, multi-channel surface plasmon resonance (SPR) fiber sensors provide an excellent solution. However, the sensing bandwidth is a key factor affecting the sensor performance. In this paper, we explore a method to modulate the sensing bandwidth using the TiO 2 film. A dual-channel SPR sensor with a wide sensing bandwidth is proposed. In this sensor, no-core fiber (NCF) is used as the sensing probe, and multimode fibers are used for the transmission of optical signals. The sensor has a cascaded composite film structure, the region coated with Ag film as the refractive index sensing region and the region coated with Ag/TiO 2 /PDMS as the temperature sensing region. The experimental results show that the sensing bandwidth of the sensor varies for different TiO 2 coating times. It indicates that the TiO 2 film can regulate the sensing bandwidth flexibly. Therefore, to achieve the optimal sensing effect, the TiO 2 coating time can be flexibly adjusted according to the RI characteristics of the environment. The maximum sensitivity of this dual-channel sensor is 4.5 nm/°C and 3151 nm/RU when the temperature range is between 10 and 80 °C and the RI range is between 1.333 and 1.385, respectively. In addition, we discuss the repeatability and stability of this dual-channel sensor. [ABSTRACT FROM AUTHOR]