Femtosecond Drift Photocurrents Generated by an Inversely Designed Plasmonic Antenna.

Area of Science:

• Optics and Photonics
• Materials Science
• Condensed Matter Physics

Background:

• Photocurrents are vital for light detection, photovoltaics, and THz radiation generation.
• Metal nanostructures offer precise light control and light-driven electron motion via surface plasmons.
• Limited use of metals for photocurrent generation despite abundant methods.

Purpose of the Study:

• To demonstrate enhanced photocurrents using gold nanostructures and a magneto-optical process.
• To explore the inverse Faraday effect for photocurrent generation.
• To enable dynamic photocurrent modulation and THz emission.

Main Methods:

• Inverse design optimization of gold nanostructures.
• Fine-tuning light field amplitude, polarization, and gradients.
• Utilizing a magneto-optical process derived from the inverse Faraday effect.

Main Results:

• Achieved enhanced, volumetric, unidirectional, intense, and ultrafast photocurrents.
• Demonstrated dynamic photocurrent modulation by varying optical pulse duration.
• Potential for generating intense, ultrafast planar magnetic fields and frequency-tunable THz emission.

Conclusions:

• Gold nanostructures can generate significant photocurrents through a magneto-optical inverse Faraday effect.
• The process allows for ultrafast magnetic material manipulation.
• Promising applications in nanoscale THz spectroscopy and THz emission sources.