Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors

Getinet Woyessa,Andrea Fasano,Christos Markos,Ole Bang,Kristian Nielsen,Alessio Stefani,Henrik K Rasmussen

doi:10.1364/oe.24.001253

Abstract

We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured POFs.

Highlights

A lot of research has gone into developing low loss polymer optical fibers (POFs) [1,2]
The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8μm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 μm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C
In order to explore the potential of this fiber for sensing, fiber Bragg gratings were inscribed in the fabricated SIPOF

Summary

Introduction

A lot of research has gone into developing low loss polymer optical fibers (POFs) [1,2]. As for the realization of the all-solid preform and/or fiber, techniques, such as batch extrusion, continuous extrusion, interfacial-gel polymerization, chemical vapor deposition, and centrifugation have been used [13,14,15,16] Using these methods, fabrication of single mode POFs is difficult because it is not easy to control dopant diffusion from core to cladding during the polymerization of monomers in the preform making process. We started the preform fabrication by casting the cladding material, ZEONEX 480R produced by ZEON CORPORATION with a glass transition temperature of 138°C [25], from granulates into a solid rod This method differs from chemical casting [32] as it does not involve any polymerization process. The end facet of the fabricated SIPOF is shown as inset in Fig. 1 (a)

Refractive index profile and loss measurement

Fiber Bragg grating inscription and characterization

Findings

Conclusion