Discontinuous Tapered Surface Plasmon Polariton Waveguides with Gap

Area of Science:

• Photonics and Plasmonics
• Nanophotonics
• Waveguide Technology

Background:

• Surface plasmon polaritons (SPPs) are electromagnetic waves propagating at the interface of a dielectric and a metal.
• Controlling SPPs is crucial for developing advanced optical devices.
• Existing waveguide structures often suffer from high losses or limited tunability.

Purpose of the Study:

• To investigate the characteristics of discontinuous tapered surface plasmon polariton waveguides with a gap (DTG-SPPWs).
• To assess the feasibility of controlling guided SPPs at a telecommunication wavelength (1.55 μm).
• To explore the potential of DTG-SPPWs as plasmonic modulation devices.

Main Methods:

• Fabrication of DTG-SPPWs using gold metal and a low-loss polymer cladding.
• Systematic variation of taper widths (2-10 μm) and lengths (1-8 μm) in the input and output waveguides.
• Characterization of coupling losses and normalized transmissions (NTs) of the waveguides.
• Analysis of SPP control through interaction with an applied force in the gap.

Main Results:

• Achieved coupling losses below 0.055 dB for an 8 μm gap and various taper widths.
• Observed normalized transmissions (NTs) below -0.060 dB for various taper widths.
• Attained NTs below -0.069 dB for various taper lengths.
• Demonstrated a maximum NT of -0.042 dB with specific taper dimensions (6 μm width, 3 μm length).

Conclusions:

• DTG-SPPWs exhibit low coupling losses and high transmission efficiency at 1.55 μm.
• The waveguide design allows for effective control of guided SPPs.
• DTG-SPPWs show significant potential for application in novel plasmonic modulation devices.