Plasmonic Sensors Based on Plastic Light-Diffusing Fibers ^†

Abstract

A very simple to realize, low-cost, and highly sensitive plasmonic sensor, based on a polymeric light-diffusing fiber (LDF), is presented. The proposed surface plasmon resonance (SPR) sensor is realized by sputtering a gold nanofilm on an LDF made of PMMA. More specifically, a plastic LDF manufactured by GLOBAL ENGINEERING NETWORK SRL (Dosson di Casier, Italy) is used to realize this sensor. The optical fiber is an uncladded POF, with a simil-PMMA core of about 1600 μm in diameter and a removable jacket of about 400 μm (total diameter of about 2 mm). The SPR sensor is achieved by removing the jacket with a mechanical stripper and covering the exposed LDF surface with a 60 nm-thick gold film with a length of about 120 mm. The obtained sensor’s sensitivity varies linearly with the refractive index, and it ranges from about 1000 (nm/RIU) to almost 3000 (nm/RIU) in the considered refractive index range (from 1.332 RIU to 1.392 RIU). The obtained sensitivity values are comparable with those achieved using other SPR optical fiber sensors, but with the advantage of having a very simple production process, which does not require optical fiber modifications (such as the polishing process, tapering process, etc). So, the proposed LDF-based plasmonic sensor could be used to realize novel kinds of optical biosensors and chemical sensors.