Precise Control of Laser-Induced Periodic Surface Structures using Angle of Incidence and Polarization

Laser-induced periodic surface structures (LIPSS) produced using ultrafast laser processing have been extensively studied for applications such as structural coloration. However, achieving uniform LIPSS with controlled spatial frequency remains challenging. LIPSS varies with parameters including laser wavelength, angle of incidence (AOI), laser energy density, and the number of laser pulses. Controlling laser wavelength and AOI can be impractical for spatially varying LIPSS. This paper explores the polarization dependency of LIPSS periodicities and selective coupling into the two branches of low-spatial frequency LIPSS-I (LSFL-I) observed at off-normal incidences. High and low-frequency LSFL-I periodicities emerge with off-normal AOI in TM illumination, consistent with the laser-SPP interference model. Adjusting beam polarization according to the laser-SPP model provides a convenient method to spatially control LIPSS. Notably, large TE illumination by changing the polarization suppresses the low-frequency LSFL-I mode, enabling improved fabrication of highly tunable single-frequency LIPSS gratings.