Li Jian
Harbin Engineering University, China
Title: Temperature sensitivity enhancement of the gold thin film-coated long-period fiber grating
Biography
Biography: Li Jian
Abstract
Long-period fiber grating (LPFGs) have attracted considerable attention recently for many applications in fiber sensors. The LPFGs can measure various physical parameters, such as, temperature, strain, refractive index and curvature. In our work, we provide a method to enhance the temperature sensitivity of LPFG. We propose a new type of LPFG, using the filament heating method for measurement of temperature. The LPFG is composed of many micro-tapers, which were fabricated using a GPX-3000 glass processing system (Vytran Corp). By using the Vytran Corp, the heating element was kept fixed and the translation stages with fiber clamps were moved in the same direction with different velocities. We can control the relative moving velocity of the translation stages and the power of heating filament to fabricate different geometric profiles micro-tapers. We used a vacuum coating machine (JS-1600). The thickness of gold thin film increased from 0 nm to 100 nm, and then increased to 200 nm. We tested the temperature sensitivities of the LPFG at three film thicknesses, respectively. The LPFG was placed in a temperature control chamber to test the temperature response. When the environmental temperature increased from 22 to 222ºC, the resonance wavelength had a red shift. The temperature sensitivity of the LPFG with no gold film is 48 pm/ºC. The temperature sensitivities of the 100 nm and 200 nm gold thin film-coated LPFGs are approximately 71 and 67 pm/ºC, respectively. We can enhance the temperature sensitivity of the LPFG by gold thin film-coated. The temperature sensitivity of the LPFG increases first and then decreases with the increase of gold film thickness, which is higher than the temperature sensitivity before coating.