Extraction of higher-order nonlinear electronic response in solids using high harmonic generation.

Area of Science:

• Optoelectronics
• Quantum Optics
• Materials Science

Background:

• Nonlinear susceptibilities are crucial for ultrafast lightwave-driven optoelectronics.
• Previous methods could only determine 3rd order nonlinear susceptibility.
• High harmonic generation (HHG) offers potential for higher-order nonlinear susceptibility extraction but lacks direct correspondence.

Purpose of the Study:

• To establish a direct correspondence between high harmonics and nonlinear susceptibilities.
• To extract high-order nonlinear susceptibilities (7th, 9th, and 11th) from sapphire.
• To explore the potential for advanced optical signal processing.

Main Methods:

• Utilizing the highly nonlinear nature of high harmonic generation (HHG).
• Developing a regime for direct correspondence between HHG and nonlinear susceptibilities.
• Analyzing angular-resolved periodicities in extracted susceptibilities.

Main Results:

• Successfully extracted 7th, 9th, and 11th order nonlinear susceptibilities from sapphire.
• Observed angular-resolved periodicities in susceptibilities linked to crystal band structure variations.
• Demonstrated a clear correspondence between high harmonics and nonlinear susceptibilities.

Conclusions:

• This work establishes a method for characterizing high-order nonlinear susceptibilities via HHG.
• The findings pave the way for multi-channel optical signal processing.
• Laser polarization can be used to control optical signal processing channels.