Influence of Polarization Direction on Damage Threshold of x-Cut Lithium Niobate(Invited)
Through femtosecond laser single-pulse experiments,we investigated the influence of polarization directions(0°,45°,90°,and 135°)on the damage threshold of x-cut lithium niobate(LN)crystals.We found that the material damage threshold exhibited considerable polarization dependence,with the damage threshold along the 90° polarization direction being lower than those in other polarization directions.Through first-principles calculations,we confirmed that tunneling ionization caused by the femtosecond laser mainly breaks Nb—O bonds.Along the incident polarization angle of 90°,more number of Nb—O bonds are easily broken,thereby reducing the damage threshold in that polarization direction.This study contributes to an in-depth understanding of the ablation of ultrafast lasers on LN crystal surfaces and has an important reference value for the laser preparation of functional devices on LN crystal surfaces.