Photochemical long-period grating fabrication in pure-fused-silica photonic crystal fiber

We report on first photochemical recording of a long-period fiber grating (LPFG) in a pure fused silica photonic crystal fiber (PCF), which is based on two-photon absorption (TPA) of high-intensity femtosecond 264 nm pulses. The main disadvantage of previously used nonphotochemical methods of LPFG inscription in PCF fiber (electric arc, mechanical pressure or CO₂ laser irradiation) is that they easily damage the fragile holey structure, especially in PCFs with large hole diameters.