CO2 laser writing of long-period fiber grating in photonic crystal fiber under tension

We demonstrate that the efficiency of CO2 laser writing of longperiod fiber gratings in a solid-core photonic crystal fiber (PCF) can be enhanced greatly by applying tension to the fiber during the writing process through the mechanism of frozen-in viscoelasticity. Using this mechanism, we are able to write strong gratings in PCFs with a dosage of CO2 laser radiation low enough not to cause any significant fiber structure deformation. (C) 2009 Optical Society of America