High efficiency coupling to metal-insulator-metal plasmonic waveguides

Area of Science:

• Plasmonics
• Antenna Engineering
• Nanophotonics

Background:

• Metal-insulator-metal (MIM) plasmonic waveguides offer unique light-matter interaction properties.
• Dual-Vivaldi antennas provide broadband radiation characteristics.
• Efficient coupling between free-space light and plasmonic waveguides is crucial for device performance.

Purpose of the Study:

• To design and investigate a periodic array of dual-Vivaldi antennas integrated with MIM plasmonic waveguides.
• To optimize the design for high infrared light absorbance efficiency.
• To achieve efficient in-coupling of free-space light into MIM waveguides.

Main Methods:

• Full-wave electromagnetic analysis was employed for design optimization.
• The study focused on optimizing MIM waveguides compatible with DC leads.
• Nanofabrication techniques were used to realize test devices.

Main Results:

• An in-coupling efficiency of 41% was achieved for free-space to MIM waveguide coupling at 1373 nm.
• A sub-wavelength unit cell geometry was utilized.
• A modified design with a backplane reflector predicted a higher efficiency of up to 85%.

Conclusions:

• The integrated antenna-waveguide system demonstrates significant potential for infrared light absorption.
• The proposed design achieves efficient coupling and high absorbance.
• Experimental validation using far-field optical spectroscopy confirmed antenna-waveguide matching.