Fabrication of Long-Period Fibre Gratings Using 800 nmFemtosecond Laser Pulses

Abstract

Long-period fibre gratings inside standard single-mode opticalcommunication fibres are successfully fabricated with infraredfemtosecond laser pulses. The refractive index perturbations are wellconfined within the fibre core by choosing the proper laser focusingparameters and translation speed of the fibre during the direct laserwriting process. With the self-focusing effect considered and at aconstant average irradiation dose of 1.62×103 J/(cm2μm),the threshold intensity for fabricating long-period gratings withinfrared femtosecond laser pulses is determined to be 5.13×1013 W/cm2.