Surface birefringence in FTO thin film fabricated by ultrafast laser

Abstract

Ultrafast laser-induced periodic surface structures (LIPSSs) have been studied intensely in the last two decades, which have become a useful method for surface nanostructures and are widely used to tune surface properties. This paper reported the fabrication of high-spatial-frequency LIPSSs (HSFLs) on FTO film induced by 1,030[Formula: see text]nm femtosecond laser. The morphology, duty cycle and birefringence effects of HSFLs were studied in detail by changing the laser fluence and scanning speed. Clear and uniform HSFLs were formed over the entire ablated area when the laser fluence and scanning speed were 89[Formula: see text]mJ/cm2 and 0.01[Formula: see text]mm/s, respectively. The duty cycle of the HSFL was measured to be as high as 0.36, and the thickness of the HSFL layer was found to be in the range of 409–546[Formula: see text]nm. The phase retardation of the FTO film with HSFLs could reach up to 96[Formula: see text]nm and could be used as an optical attenuator with a tunable range of 71–100% for 532[Formula: see text]nm linear polarized light.