LPG inscription in mPOF for optical sensing

Abstract

We demonstrate a long period grating (LPG) inscription in microstructured polymer optical fibers (mPOFs) using a single 248 nm UV laser pulse of 15 ns duration for every inscription point using a point by point technique with total length of 25 mm. The fabrication time indicates shortening for a single coupling point (15 ns against 42 s reported in literature). A grating with 20 dB transmission dip has been fabrication by using two UV pulses for each coupling point. The device has been fabricated in mPOF with a core that has been doped with benzyl dimethyl ketal (BDK) for photosensitivity increase. The strain and temperature responses of the fabricated gratings under different conditions have been characterized in order to assess the viability for sensing applications. Better performance was achieved with suitable post annealing process of the gratings.

Suspended-Core Microstructured Polymer Optical Fibers and Potential Applications in Sensing

“…Within this region, PMMA-based MPOFs exhibit an extremely low loss, allowing up to 10 m of fiber to be used. Strain [61,62,63], temperature [64], pressure [65], humidity [66,67], and biological sensors [68] using MPOF based LPGs have already been demonstrated. In 2009, a mechanically-induced LPG in an MPOF has been proposed for strain monitoring.…”