Observation of inner surface laser-induced periodic surface structures in a microhole produced in a glass optical fiber by varying femtosecond laser pulse number and energy

Laser-induced periodic surface structures (LIPSS) formation was observed inside a microhole produced in an optical fiber, when the femtosecond laser pulse number and the laser energy were optimized to be 150 and 30μJ, respectively. We have also found that LIPSS were formed only at the bottom of the microhole, which may be responsible for the strong evanescent field produced by the femtosecond laser propagating inside the microhole.