Work

High-spatial-frequency nanoripples induced on a WS 2 film by femtosecond laser pulses for second harmonic generation and Raman scattering manipulation

Year: 2025

Type: article

Abstract: Transition metal dichalcogenides (TMDCs) have attracted great interest due to their unique layer-related electronic and optical properties, which exhibit potential applications in optoelectronic devices. However, the fabrication of nanostructures on the surface of a TMDC film, which is necessary for their device applications, remains a big challenge. Direct laser writing has been widely employed to fabricate periodic structures on the surface of metallic and dielectric materials. Here, we demonstrate that high-spatial-frequency nanoripples with a period of only one-tenth of the laser wavelength could be produced on the surface of a WS 2 film by using femtosecond laser ablation. The period of nanoripples is controlled by adjusting the WS 2 film thickness and laser fluence, and their orientation is perpendicular to the writing laser polarization. It is revealed that the fabricated nanoripples exhibit polarization control for reflected light, second harmonic wave, and Raman signal. Interestingly, the second harmonic generation is enhanced (suppressed) when the polarization of the excitation light is parallel (perpendicular) to the orientation of nanoripples. In addition, the Raman signals are greatly enhanced in the presence of nanoripples. Based on numerical simulation, it is unveiled that the modification in the electric field distribution in the WS 2 film induced by nanoripples plays a crucial role in the second harmonic generation. At the same time, Raman signals are enhanced by the compressive strain formed in nanoripples. Our findings indicate the potential applications of the high-spatial-frequency nanoripples in controlling the optical properties of the TMDCs and pave the way for realizing polarization-sensitive optical storage and display based on TMDCs.

Source: Optics Express

DOI: 10.1364/oe.555503

Authors: Jinshan Luo, Shulei Li, Shimei Liu, Yuheng Mao, Zhuo Wang, Sheng Lan

Institution: Guangdong Polytechnic Normal University

Language: English

Topic: Laser Material Processing Techniques

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270

Funders: National Natural Science Foundation of China, Natural Science Foundation of Guangdong Province