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Updated: Mar 29, 2026
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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
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Disentangling Electronic and Ionic Nonlinear Polarization Effects in Bulk THz Kerr Response
Chao Shen1, Maximilian Frenzel2, Sebastian F Maehrlein2,3,4
1ISTA (Institute of Science and Technology Austria), Klosterneuburg 3400, Austria.
Physical Review Letters
|March 27, 2026
Summary
Nonlinear terahertz (THz) spectroscopy reveals insights into material dynamics. This study identifies a Raman mode and kinematic effects in LaAlO3, offering a framework for interpreting complex nonlinear THz-Kerr spectra.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Terahertz (THz) spectroscopy probes low-energy excitations in materials.
- Nonlinear THz spectroscopy offers deeper insights into material dynamics and mode interactions.
- Interpreting nonlinear spectra is complex due to potential artifacts unrelated to intrinsic material properties.
Purpose of the Study:
- To investigate the nonlinear THz-induced Kerr effect in lanthanum aluminate (LaAlO3).
- To differentiate between intrinsic material dynamics and kinematic effects in nonlinear THz spectroscopy.
- To establish a framework for interpreting nonlinear THz-Kerr response in complex materials.
Main Methods:
- Utilized nonlinear THz-induced Kerr effect measurements.
- Analyzed temporal oscillations of the Kerr signal.
- Investigated phase matching effects of probe and pump THz fields.
Main Results:
- Identified an Eg Raman mode at 1.1 THz excited via a two-photon process.
- Observed peaks at 0.86 and 0.36 THz attributed to phase matching effects.
- Demonstrated the significant influence of kinematic effects on the THz-Kerr response.
Conclusions:
- Kinematic effects play a crucial role in shaping nonlinear THz-Kerr spectra.
- Off-resonant electronic hyperpolarizability mediates spectral features.
- Developed a framework for accurate interpretation of nonlinear THz spectroscopies in complex materials.
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