Gapped Surface Plasmon Polariton Waveguides for Plasmonic Signal Modulation Applications

Area of Science:

• Photonics and Plasmonics
• Materials Science
• Nanotechnology

Background:

• Surface plasmon polaritons (SPPs) are electromagnetic waves confined to metal-dielectric interfaces.
• Controlling SPP propagation in waveguides is crucial for integrated photonic devices.
• Gapped waveguides offer a potential mechanism for SPP manipulation.

Purpose of the Study:

• To investigate the characteristics of gapped surface plasmon polariton waveguides (G-SPPWs).
• To assess the feasibility of controlling guided SPPs via applied force in the gap.
• To evaluate performance at a telecommunication wavelength of 1.55 μm.

Main Methods:

• Fabrication of insulator-metal-insulator (IMI) waveguides using gold and a low-loss polymer.
• Experimental analysis of SPP propagation and coupling losses across varying gap lengths, widths, and metal thicknesses.
• Characterization of normalized transmissions for different G-SPPW configurations.

Main Results:

• G-SPPWs successfully guided SPPs across gaps up to 12 μm with low coupling losses.
• Coupling loss remained below 0.05 dB for gaps up to 8 μm, widths up to 8 μm, and thicknesses up to 50 nm.
• Maximum normalized transmission of -0.041 dB achieved with a 2 μm long, 2 μm wide, and 20 nm thick G-SPPW.

Conclusions:

• G-SPPWs exhibit efficient SPP propagation over gaps, indicating low loss.
• The demonstrated control of guided SPPs via gap interaction suggests potential for tunable plasmonic devices.
• G-SPPWs are promising candidates for novel plasmonic modulators.