A versatile two-dimensional terahertz spectroscopy platform with dual independently controlled intense pulses

Area of Science:

• Optics and Photonics
• Condensed Matter Physics
• Spectroscopy

Background:

• Two-dimensional terahertz (2D THz) spectroscopy is a powerful technique for probing ultrafast dynamics in materials.
• Existing THz spectroscopy platforms often lack the flexibility and intensity required for high-order nonlinear measurements.
• Investigating nonlinear optical phenomena in the terahertz (THz) frequency range is crucial for understanding fundamental material properties.

Purpose of the Study:

• To present a novel, high-intensity two-dimensional terahertz (2D THz) spectroscopy platform.
• To demonstrate the platform's capability in resolving high-order nonlinear optical responses.
• To investigate nonlinear wave-mixing in silicon using dual-frequency THz excitation.

Main Methods:

• Utilizing dual high-intensity THz sources generated in LiNbO3 crystals via the tilted-pulse-front technique.
• Employing an integrated periscope beam combiner for efficient THz beam combination and overlap.
• Achieving independent control over polarization, spectrum, and intensity of individual THz pulses.

Main Results:

• Successfully resolved polarization-dependent nonlinear signals up to the 11th order in a 2D spectrum.
• Demonstrated the platform's performance by investigating nonlinear wave-mixing in silicon at room temperature.
• Confirmed the capability of the tabletop laser system for exploring complex THz material responses.

Conclusions:

• The developed 2D THz spectroscopy platform offers enhanced experimental flexibility and high sensitivity.
• The instrument is capable of elucidating complex nonlinear mechanisms in materials at THz frequencies.
• This work paves the way for advanced studies of material properties using nonlinear THz spectroscopy.