Chiral Bismuth Halide Metasurfaces for Enhanced Second Harmonic Generation.

Area of Science:

• Optoelectronics
• Materials Science
• Nanophotonics

Background:

• Hybrid organic-inorganic metal halides offer tunable optical properties and solution processability.
• Chiral bismuth halides exhibit strong second-order nonlinear susceptibility, stability, and low toxicity, ideal for nonlinear nanophotonics.
• Efficient second-harmonic generation (SHG) in thin films is often hindered by weak light-matter interactions.

Purpose of the Study:

• To enhance light-matter interactions for efficient SHG in chiral bismuth halide thin films.
• To develop a scalable fabrication method for integrating chiral bismuth halides with nanophotonic structures.
• To establish a novel platform for cost-efficient, nontoxic nonlinear photonic devices.

Main Methods:

• Integration of a chiral bismuth iodide (R-MBA)BiI4 with a nonlocal metasurface.
• Fabrication of the metasurface using femtosecond laser ablation.
• Characterization of SHG enhancement in visible and infrared ranges.

Main Results:

• The resonant metasurface significantly enhances SHG compared to unpatterned films.
• Guided mode resonances were achieved in both visible and infrared spectral ranges.
• Demonstrated a scalable and versatile fabrication technique for the metasurface.

Conclusions:

• The resonant metasurface effectively overcomes limitations of weak light-matter interaction in chiral bismuth halide thin films.
• This work presents a new platform for developing efficient nonlinear photonic devices using solution-processed, nontoxic materials.
• The findings pave the way for advanced applications in nonlinear nanophotonics.