Second-harmonic optical vortex conversion from WS₂ monolayer

Area of Science:

• Nonlinear optics
• Quantum information processing
• Materials science

Background:

• Orbital angular momentum (OAM) of light is crucial for optical communication and quantum information processing.
• Nonlinear optical media are key for generating and converting OAM.
• Atomically thin materials offer unique platforms for advanced optical functionalities.

Purpose of the Study:

• To demonstrate OAM conversion of optical vortices using a single WS2 monolayer via second-harmonic generation.
• To investigate the role of valley-contrasting physics in WS2 nonlinear optics.
• To explore potential applications in miniaturized optoelectronics and quantum computing.

Main Methods:

• Utilized a single atomically thin WS2 monolayer.
• Employed second-harmonic generation (SHG) for OAM conversion.
• Operated at room temperature.

Main Results:

• Successfully demonstrated OAM conversion of optical vortices.
• Showcased precise control over output circular polarization via WS2's valley-contrasting physics and nonlinear optical selection rules.
• Achieved this conversion using only a single WS2 monolayer.

Conclusions:

• Single WS2 monolayers can efficiently convert OAM of optical vortices.
• Valley physics in WS2 dictates the polarization of generated second-harmonic vortices.
• These findings enable the development of compact valleytronic devices for chiral photonics, nonlinear beam generation, and quantum computing.