Micropattern-assisted absorption enhancement and wettability surface on ZnO via single femtosecond laser beam tailoring

Herein, we report significant micropattern-assisted absorption enhancement on crystalline ZnO fabricated by a single femtosecond laser beam (400 nm, 35 fs, kHz). This two-dimensional micropattern, which is achieved by one-step femtosecond laser tailoring, sharply contrasts the traditional laser-induced periodic surface structure. The large-area preparation of two-dimensional micropatterns can be achieved via an overlapped scanning method, showing potential practical applications. We find that the absorption shows an increasing trend, with maximum values of 90-99% in the ultraviolet spectral regions and 75-80% in the visible spectral regions. Additionally, theoretical results demonstrate that a strong electric field enhancement phenomenon exists on the two-dimensional structure from the ultraviolet to near-infrared wavelengths. We also determine the liquid contact angle of these micropattern structures, which exhibit controlled wettability characteristics that are dependent on laser energy.