Ultrafast all-optical switching in nonlinear 3R-MoS₂ van der Waals metasurfaces

Area of Science:

• Nonlinear optics
• Materials science
• Condensed matter physics

Background:

• Second-order nonlinear optical processes are crucial for photonics and spectroscopy.
• Material platforms are key to advancing nonlinear optical applications.
• Van der Waals crystals offer unique optoelectronic properties.

Purpose of the Study:

• To demonstrate the nonlinear optical properties of 3R-MoS2.
• To enhance second-harmonic generation (SHG) efficiency using metasurfaces.
• To achieve ultrafast optical switching utilizing material symmetry.

Main Methods:

• Fabrication of 3R-MoS2 metasurfaces with high quality factor resonances.
• Utilizing quasi-bound states in the continuum (qBIC) for efficiency enhancement.
• Employing degenerate pump-probe spectroscopy for ultrafast characterization.

Main Results:

• Achieved SHG efficiency enhancement exceeding 10^2 in 3R-MoS2 metasurfaces.
• Demonstrated ultrafast SHG polarization switching with near-unity modulation depth.
• Characterized operation speeds limited only by excitation pulse duration.

Conclusions:

• 3R-MoS2 is a transformative platform for nanoscale nonlinear optics.
• The material offers high conversion efficiencies and ultrafast response times.
• Potential applications include advanced pulse measurement, integrated photonics, and quantum technologies.