Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

Area of Science:

• Nanophotonics
• Plasmonics
• Optical Engineering

Background:

• Plasmonic components offer nanoscale integration of photonics and electronics.
• Active control of plasmons is crucial for device functionality.
• Achieving all-optical modulation with nanometer mode volume and high depth remains a challenge.

Purpose of the Study:

• To demonstrate all-optical switching of plasmonic nanoparticle scattering.
• To achieve high modulation depth and bandwidth with low optical power.
• To explore applications in superresolution imaging.

Main Methods:

• Utilizing scattering from plasmonic nanoparticles with volumes < 0.001 μm³.
• Investigating photothermal effects for optical switching.
• Measuring modulation depth, spectral bandwidth, and nonlinear optical properties.

Main Results:

• Optical switching of scattering with < 100 μW power and > 80% modulation depth.
• Achieving a spectral bandwidth of ~100 nm.
• Demonstrating a single-particle nonlinearity of ~10⁻⁹ m²/W, the highest for metallic materials.
• Enhancing optical resolution to λ/5 (λ/9 after deconvolution) for superresolution imaging.

Conclusions:

• All-optical control of plasmonic scattering is achievable at the nanoscale.
• Photothermal effects provide a mechanism for efficient all-optical modulation.
• This technology enables low-intensity superresolution imaging and opens new avenues in nanophotonics.