Highly sensitive distributed liquid-droplet sensor based on evanescent-wave linearly chirped fiber Bragg grating

We propose a highly-sensitive distributed addressable liquid-droplet sensor based on an evanescent-wave linearly chirped fiber Bragg grating (LCFBG). Due to liquid-droplet-induced increase of the localized effective refractive index, a transmission window is generated within the original reflection stopband of LCFBG. Utilizing the spatial encoding feature of Bragg wavelength in LCFBG and spectrum properties of the created passband, both numerical and experimental results demonstrate that the position, size, and refractive index information of multiple distributed discrete liquid-droplets can be detected simultaneously.