Spectral characteristic of symmetric double tapered plastic optical fibers

Plastic optical fiber (POF) sensor has been immensely developed for many sensing applications including physical and chemical/bio sensor. Since it offers the advantages of non-destructive, easy fabrication and installation, immunity to electromagnetic interference, compact, low fabrication costs and higher durability compare to silica fiber sensor. Tapered POF is one of the modified structures on POF by reducing its diameter and induces guided modes in the core to be evanescent modes. As a sensor, the tapered structure on POF increase the sensitivity of non-tapered POF. The number of tapers on optical fiber affect its characteristics as well. Hence, it is important to investigate the characteristic of tapered POF with the variation on number of tapers. In this paper, the spectral characteristic of symmetric double tapered POF (DT POF) was investigated. The fabrication of symmetric DT POF was conducted by reducing the core diameter using chemical process as described in. The core diameter and the length of the tapered were fixed at 0.45 mm and 1 cm, respectively. The distance between two tapers was varied from 1-3 cm. Transmission spectrum characterization of symmetric DT POF was measured at near infrared wavelength range (900-1600 nm) using a spectrometer by OTO-Photonics.