High-reflectivity draw-tower fiber Bragg gratings—arrays and single gratings of type II

Fiber Bragg gratings (FBG) were manufactured during the fiber drawing process [draw tower grating (DTG)] with excellent reflectivity values. This was done in the region of 1550 nm by single pulses of a 248-nm excimer laser applied during the fiber drawing process of single mode fibers. An improved setup for the writing process and special photosensitive fibers enable the manufacture of type I DTG arrays with a reflectivity of up to 40% and type II DTGs with a reflectivity near 100%. Details of the setup and results of the DTG arrays and DTGs of type II are reported.