High Sensitivity Characteristics of Tapered Fiber Plasmon Sensor With Gold Nanoparticles in 1500 nm Wavelength Band

A tapered fiber plasmon sensor with a tip angle of about 30 degrees was fabricated to realize optical absorption and application to an optical sensor using localized plasmon in the 1500 nm wavelength band. The sharp tip angle of a single-mode fiber (SMF) was well controlled by using a highly GeO2-doped single-mode fiber (SMF) and optimizing the etching conditions with buffered fluoric acid. Gold nanoparticles (Au-NPs) with a diameter of 40 nm were deposited by treating the surface of a tipped SMF with silane coupling. The relationship between Au NPs deposition time and deposition ratio was studied to control Au NPs distribution and pursue higher sensitivities. The wavelength sensitivity of 662 nm/RIU was expected at Au NPs deposition ratio of 34.9 % in the analysis, and actually a high sensitivity of 677 nm/RIU at 35.3 % was experimentally demonstrated.