Effect of LiNbO3 crystals temperature on ultra-fast laser induced periodic surface structures

The effect of LiNbO3 crystals temperature on the formation of periodic surface structures induced by femtosecond laser pulse with duration of 120 fs and wavelength of 800 nm was investigated theoretically and experimentally. Firstly, experimental results show that surface periodic ripples tend to form on high temperature LiNbO3 crystals. Then, an improved rate equation including Drude model was proposed to analysis the dynamic of free carrier density and optical properties. The theoretical calculation results show that, the LiNbO3 crystal at high temperature is more likely to excite high-density carriers under femtosecond laser irradiation, which benefits from the change of carrier excitation mechanism. Temperature-controlled femtosecond laser micro-/nano- processing will become a new effective method for fabrication wide-gap transparent dielectric materials.