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Interference tunable second harmonic generation for two-dimensional materials in layered structures
Optics Express
|June 29, 2023
Summary
We demonstrate tunable second harmonic generation (SHG) in layered 2D materials. Constructive interference between light waves maximizes SHG signals, achieving a three-order-of-magnitude enhancement in MoS2-based structures.
Area of Science:
- Materials Science
- Optics
- Condensed Matter Physics
Background:
- Second Harmonic Generation (SHG) is a nonlinear optical process.
- Two-dimensional (2D) materials offer unique optical properties.
- Controlling SHG in layered structures is crucial for optoelectronic applications.
Purpose of the Study:
- To experimentally investigate the tunability of SHG in a 2D material/dielectric film/substrate structure.
- To understand the interference mechanisms governing SHG enhancement.
- To achieve significant signal variations through structural optimization.
Main Methods:
- Fabrication of a layered structure: monolayer MoS2 on TiO2 dielectric film on an Ag substrate.
- Experimental measurement of SHG signals under varying conditions.
- Analysis of interference effects between incident and reflected fundamental light, and between upward and downward SH light.
Main Results:
- SHG tunability was observed in the 2D material layered structure.
- Maximal SHG enhancement occurs when both fundamental and second harmonic interferences are constructive.
- A three-order-of-magnitude variation in SHG signals was demonstrated from a monolayer MoS2/TiO2/Ag structure.
- Optimal conditions involve a highly reflective substrate and a dielectric film with a significant refractive index difference.
Conclusions:
- The study experimentally confirms the tunability of SHG in 2D material-based layered structures.
- Interference phenomena play a critical role in modulating SHG intensity.
- The findings provide a pathway for optimizing nonlinear optical responses in 2D materials for advanced photonic devices.
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