Turning the corner: efficient energy transfer in bent plasmonic nanoparticle chain waveguides

Area of Science:

• Plasmonics
• Nanophotonics
• Optical Engineering

Background:

• Subwavelength plasmonic waveguides are essential for integrating optical and electrical components.
• Bending losses in plasmonic waveguides limit device performance and propagation distances.
• Complex architectures like sharp turns are necessary for advanced plasmonic circuits.

Purpose of the Study:

• To investigate bending losses in plasmon propagation through silver nanoparticle chains.
• To demonstrate loss-free propagation of surface plasmon polaritons around sharp turns.
• To compare propagation lengths of subradiant and super-radiant plasmon modes.

Main Methods:

• Utilized bleach-imaged plasmon propagation (BlIPP), a far-field fluorescence technique.
• Created permanent maps of plasmonic near-fields by fluorophore bleaching.
• Measured propagation lengths at 633 nm for straight and 90° bent silver nanoparticle chains.

Main Results:

• Surface plasmon polaritons propagated around 90° turns in silver nanoparticle chains with negligible bending losses.
• Measured propagation lengths for straight and bent chains were comparable (8.0 ± 0.5 μm and 7.8 ± 0.4 μm, respectively).
• Subradiant plasmon modes exhibited longer propagation lengths than super-radiant modes, independent of input polarization.

Conclusions:

• Sharp turns in silver nanoparticle chains do not induce significant bending losses for surface plasmon polaritons.
• Subradiant plasmon modes offer enhanced propagation distances, beneficial for plasmonic waveguide design.
• These findings enable the development of complex, integrated plasmonic circuits with improved performance.