Tailoring Second-Harmonic Emission from (111)-GaAs Nanoantennas

Area of Science:

• Nonlinear optics
• Nanophotonics
• Semiconductor physics

Background:

• Second-harmonic generation (SHG) in dielectric nanoparticles is promising for nonlinear light sources.
• Elemental semiconductors lack bulk SHG due to centrosymmetry, while III-V semiconductors like AlGaAs and GaAs are alternatives.
• Existing (100)-GaAs nanoantennas have limited control over SH emission directionality and zero forward/backward radiation.

Purpose of the Study:

• To overcome limitations in SHG directionality and control in semiconductor nanoantennas.
• To present the first SHG nanoantennas utilizing (111)-GaAs.
• To enable efficient and flexible nonlinear beam-shaping devices.

Main Methods:

• Theoretical modeling and experimental fabrication of (111)-GaAs nanoantennas.
• Embedding nanoantennas in a low-index material.
• Investigating SHG properties with varying pump polarization.

Main Results:

• Demonstrated superior forward directionality of (111)-GaAs nanoantennas compared to (100)-GaAs.
• Showcased manipulation of SHG radiation patterns by altering pump polarization.
• Maintained linear properties and nonlinear conversion efficiency during polarization tuning.

Conclusions:

• The developed (111)-GaAs SHG nanoantennas provide a solution for controlled light emission directionality.
• This breakthrough enables tunable nonlinear beam shaping, advancing semiconductor-based nonlinear optics.
• The findings pave the way for practical applications in advanced optical devices.