Efficient High-Order Harmonic Generation from the van der Waals Layered Crystal Copper Indium Thiophosphate

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nonlinear Optics

Background:

• Layered metal thio- and selenophosphates (MTPs) are van der Waals materials with diverse magnetic, ferroelectric, and optical properties.
• Recent studies highlight MTPs' potential in integrated nanophotonics due to efficient harmonic generation and high third-order nonlinear optical properties.

Purpose of the Study:

• Investigate the high-order nonlinear optical response of copper indium thiophosphate (CIPS) in bulk and thin-film forms.
• Explore the generation of high-order harmonics (HHG) using intense mid-infrared laser fields.

Main Methods:

• Experimental studies of high-order harmonic generation (HHG) from CIPS crystals.
• Computational analysis using first-principles calculations.
• Utilized a 3.2 μm wavelength driving laser source.

Main Results:

• Generated odd and even harmonics up to the 10th order, exceeding the material's bandgap.
• Achieved conversion efficiencies up to 10^-7 for the fifth and seventh harmonics.
• Observed power-law scaling of harmonic intensities, indicating a perturbative nonlinear optical origin.

Conclusions:

• High-order harmonic generation in CIPS suggests potential for integrated nanophotonics.
• First-principles calculations indicate electron-electron interactions mediate the highest harmonic orders.
• Correlation-enhanced optical nonlinearity is suggested for MTPs.