Enhanced Second Harmonic Generation from Ferroelectric HfO₂-Based Hybrid Metasurfaces

Area of Science:

• Nanophotonics
• Nonlinear Optics
• Materials Science

Background:

• High-efficiency optical second harmonic generation (SHG) is crucial for advanced optical systems.
• Hybrid metasurfaces offer enhanced SHG but face integration challenges.
• On-chip integration requires CMOS-compatible nonlinear materials.

Purpose of the Study:

• To demonstrate enhanced SHG in on-chip integrated metasurfaces.
• To utilize ferroelectric Y:HfO2 thin films for improved nonlinear optical performance.
• To establish a pathway for efficient on-chip nonlinear light sources.

Main Methods:

• Fabrication of hybrid metasurfaces incorporating nanometer thin films of ferroelectric Y:HfO2 on silicon.
• Characterization of SHG intensity from hybrid metasurfaces compared to bare films and control structures.
• Determination of the effective second-order nonlinear optical coefficient (χ(2)) of Y:HfO2.

Main Results:

• A 20-fold enhancement in SHG intensity was observed from the hybrid metasurface compared to a bare Y:HfO2 film.
• A 3-fold SHG enhancement was achieved compared to a nonferroelectric HfO2 control structure.
• The effective nonlinear optical coefficient χ(2) of Y:HfO2 was measured as 6.0 ± 0.5 pm/V.

Conclusions:

• Ferroelectric Y:HfO2 thin films significantly enhance on-chip SHG.
• The developed hybrid metasurfaces provide an efficient route for on-chip nonlinear light generation.
• This work paves the way for CMOS-compatible nanophotonic nonlinear light sources.