Long Period Fiber Gratings Written in Photonic Crystal Fibers by Use of CO2 Laser

Photonic crystal fibers are usually divided into two different types of fibers： solid-core photonic crystal fibers （PCFs） and air-core photonic bandgaps fibers （PBFs）. We presented the fabrication methods and applications of long period fiber gratings （LPFGs） written in these two types of photonic crystal fibers by use of a CO2 laser. A stain sensor with a high sensitivity was demonstrated by use of an LPFG written in solid-core PCFs. An in-fiber polarizer based on an LPFG was fabricated by use of a focused CO2 laser beam to notch periodically on a PCF. A novel LPFG was written in an air-core PBF by use of a CO2 laser to collapse periodically air holes in the fiber cladding.