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Phase Engineering of Giant Second Harmonic Generation in Bi2O2Se
Zhefeng Lou1,2,3, Yingjie Zhao4, Zhihao Gong5
1Key Laboratory for Quantum Materials of Zhejiang Province, Department of Physics, School of Science and Research Center for Industries of the Future, Westlake University, Hangzhou, 310030, P. R. China.
Advanced Materials (Deerfield Beach, Fla.)
|December 5, 2024
Summary
Researchers engineered bismuth oxy-selenide (Bi2O2Se) 2D materials to achieve giant second-harmonic generation (SHG) for nonlinear optics. Strain tuning offers unprecedented control over this effect, paving the way for novel optical devices.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Optics
Background:
- Two-dimensional (2D) materials with strong second-harmonic generation (SHG) are crucial for on-chip nonlinear optics.
- A key challenge is finding materials with both high SHG efficiency and environmental stability.
Purpose of the Study:
- To demonstrate enhanced SHG in phase-engineered 2D bismuth oxy-selenide (Bi2O2Se) via uniaxial strain.
- To explore the tunability of SHG response and ferroelectric properties through strain modulation.
Main Methods:
- Uniaxial strain applied to 20 nm-thick Bi2O2Se films.
- Measurement of second-harmonic generation (SHG) signals.
- Characterization of ferroelectric phase transitions under strain.
Main Results:
- Strained Bi2O2Se exhibited SHG signals 10x stronger than NbOI2/NbOCl2 and 4 orders of magnitude higher than monolayer MoS2.
- Achieved a second-order nonlinear susceptibility of approximately 1 nm/V.
- Demonstrated a six-orders-of-magnitude tunability of SHG via strain, enabling continuous adjustment of ferroelectric phase transitions across room temperature.
Conclusions:
- Phase-engineered, strained Bi2O2Se offers colossal SHG and sensitive strain tunability.
- This air-stable 2D semiconductor is a promising candidate for developing switchable, chip-scale nonlinear optical devices.
