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Nonlinear Optical Effects Enhanced by Deep Band Crossings
Nianlong Zou1, He Li1,2, Meng Ye3
1Tsinghua University, State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Beijing 100084, China.
Physical Review Letters
|December 12, 2025
Summary
This study introduces "deep band crossings" (DBCs) within material bands to significantly boost nonlinear optical (NLO) effects. This approach enhances shift conductivity in insulators, offering a universal method for NLO applications.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nonlinear Optics
Background:
- Nonlinear optical (NLO) effects are crucial for optical applications.
- Existing research on NLO materials focuses on valence-conduction band crossings.
- Insulators, ideal for NLO, lack these specific band crossings.
Purpose of the Study:
- To explore novel band crossings for enhanced NLO effects in insulators.
- To introduce and define "deep band crossings" (DBCs).
- To demonstrate a practical method for enhancing NLO properties.
Main Methods:
- Theoretical investigation of band structures and NLO properties.
- Analysis of 2D and 3D material models.
- High-throughput computational screening.
Main Results:
- Deep band crossings (DBCs) significantly enhance NLO effects, particularly shift conductivity.
- Demonstrated enhancement in 2D with a "deep Dirac nodal point" and in 3D with GeTe's "deep Dirac nodal lines."
- High-throughput calculations confirm the widespread applicability of DBCs.
Conclusions:
- Deep band crossings offer a universal and practical strategy for enhancing NLO effects in materials.
- This approach is particularly relevant for insulators, expanding their use in NLO applications.
- Engineering band crossings provides a tunable pathway for advanced optical materials.
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