Surface birefringence in FTO thin film fabricated by ultrafast laser

作者：Chen, Long; Yang, Jian; Zhang, Fengzhuo; Zhang, Yuchan; Jiang, Qilin; Cao, Kaiqiang^*; Jia, Tianqing

来源：JOURNAL OF NONLINEAR OPTICAL PHYSICS & MATERIALS, 2022, 2250030.

DOI：10.1142/S0218863522500308

• Femtosecond laser
• periodic nanostructures
• FTO films
• birefringence effect
• phase retardance

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 1,030nm 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 89mJ/cm(2) and 0.01mm/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 409-546nm. The phase retardation of the FTO film with HSFLs could reach up to 96nm and could be used as an optical attenuator with a tunable range of 71-100% for 532nm linear polarized light.