Structured light interacts with layered semiconductor materials

The growing interest in layered transition metal dichalcogenide (TMD) materials stems from their potential applications in valleytronics devices and the ability to control valley polarization. Monolayer molybdenum disulfide (MoS₂), with its optical bandgap of 1.8eV and modulatable valley degree of freedom through circularly polarized light or strain engineering, exhibits distinct characteristics. In this study, we investigate the interaction between structured light possessing orbital angular momentum (OAM) and layered MoS₂. The interaction between optical orbital angular momentum (OAM) and materials has led to the discovery of novel and intriguing physical phenomena, with significant advancements in recent years. In this study, we investigated the resonant Raman spectroscopy of monolayer molybdenum disulfide (MoS₂) under the illumination of light with different orbital angular momentum. Excitation lasers with wavelengths of 633 nm (1.96 eV) and 532 nm (2.33 eV) were utilized, and a spatial light modulator (SLM) was employed to generate light with optical OAM, which was then used to illuminate the monolayer MoS₂ and observe the resulting Raman spectra. The experimental results revealed that, under resonant excitation, an increase in orbital angular momentum caused a blue-shift in the peak positions of the Raman spectra. This finding indicates a strong coupling between excitons and phonons in the material, where the transfer of orbital angular momentum to the layered material results in compressive strain, altering the characteristic Raman peak positions. The insights gained from this study have the potential to enhance the manipulation of spin properties in TMD materials, opening up new possibilities for spin-based optoelectronics.