Origin and Transition of Femtosecond Laser‐Induced Periodic Surface Structures on Single‐Crystalline SrTiO ₃

Abstract Femtosecond laser irradiation induces a non‐classical transition from 2D to 1D laser‐induced periodic surface structures (LIPSS) on single‐crystalline SrTiO 3 (STO). High‐resolution characterization reveals this transition occurs with increasing pulse number—without changes in laser fluence or polarization state. The first few pulses produce initial cracks and 2D LIPSS through anisotropic lattice dynamics. Later, 1D LIPSS emerge, showing laser‐polarization dependence due to periodic energy deposition from surface plasmon polaritons (SPPs)‐laser coupling at specific incidence angles. Theoretical simulations confirm that periodic electromagnetic energy redistribution—caused by SPPs‐laser interference—drives the transition, primarily due to incidence angle changes between the laser and preformed grooves. This work is crucial for understanding how multi‐pulse interactions influence LIPSS formation, enabling better control in designing advanced nanostructured surfaces. It offers promising applications in optics, optoelectronics, photovoltaics, and biosensing.