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

摘要

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. Besides, photochemical LPFG fabrication in PCF not only allows recording by adding new periods to the grating, but also by repetitive exposure over the fixed number of periods. This important improvement results in production of stronger grating resonances with narrower bandwidths.