Fabrication of surface corrugated Long Period Gratings on Plastic Optical Fibers for Refractive Index Sensing

We use a simple way to fabricate surface corrugated long period gratings (LPGs) on commercial plastic optical fibers (POFs) by die press print method. The so-obtained LPGs are proposed as refractive index (RI) sensors in this work. The LPGs imprinted on the POFs with different diameters are evaluated, and it shows that an LPG imprinted on a thin POF (with a diameter of 0.25mm) exhibits better RI sensing performance than that of the ones on thick POFs (with diameters of 0.5 and 1.0mm). When the LPG with period of 100μm, groove depth of 45μm was imprinted on the POF with a diameter of 0.25mm, the RI sensitivity of 1998%/RIU with a resolution of 2.70×10-4 RIU is obtained. The sensor is a low-cost solution for RI sensing purpose and with the features of simple structure, easy fabrication and intensity modulation at visible wavelengths.