Novel D-type Fiber Optic Localized Plasmon Resonance Sensor Realized by Femtosecond Laser Engraving

A novel fiber optic localized plasmon resonance (FO-LPR) sensor composed of a D-shape optical fiber was proposed and demonstrated in the present study. The D-shape optical fiber was fabricated by a femtosecond laser micromachining system. The dimensions of the D-shape zone were 100 mu m in depth measured from the surface of the polymer jacket layer, and the total length was 6 mm. After annealing treatment, the mean roughness of the surface was 231.7 nm as determined by AFM. The exposed surface of the D-shape fiber was modified with self-assembled gold nanoparticles to produce the FO-LPR sensor. The response of the sensor shows that the signal increases linearly with increasing refractive index. The sensor resolution of the sensor was determined to be 4.1x10(-4) RIU.