Deep-subwavelength spoof magnetic localized surface plasmon waveguiding over arbitrary bending angles.

Area of Science:

• Plasmonics
• Nanophotonics
• Waveguide technology

Background:

• Magnetic localized surface plasmons (MLSPs) are crucial for subwavelength waveguiding.
• Existing structures for MLSPs often lack flexibility in waveguide design, particularly with bending.
• Deep-subwavelength structures offer potential for miniaturized optical components.

Purpose of the Study:

• To propose and demonstrate a novel metal spiral structure (MSS) waveguide.
• To enable the propagation of MLSPs over arbitrary bending angles.
• To investigate the potential for long-distance MLSP transmission using MSS waveguides.

Main Methods:

• Theoretical analysis of MLSP propagation in MSS.
• Electromagnetic simulations to validate theoretical predictions.
• Experimental fabrication and characterization of MSS waveguides.

Main Results:

• Demonstrated propagation of MLSPs in MSS waveguides with arbitrary bending angles.
• Observed uniform coupling strengths and frequencies for adjacent MSSs with varying azimuthal angles.
• Confirmed backward propagation of MLSPs through spectral, dispersion, and field distribution analysis.
• Showcased a long S-chain of MSSs for potential long-distance MLSP waveguides.

Conclusions:

• The proposed MSS waveguide effectively supports MLSP propagation over arbitrary bending angles.
• This technology represents a significant advancement for flexible MLSP-based devices.
• MSS waveguides hold promise for future applications in long-distance, subwavelength waveguiding.