Tunable dual-channel slow light in a graphene grating plasmonic waveguide

Area of Science:

• Photonics and optical engineering
• Materials science
• Condensed matter physics

Background:

• Surface plasmon polaritons (SPPs) are electromagnetic waves confined to the interface of a conductor and a dielectric.
• Slow light phenomena, where light propagation speed is significantly reduced, are crucial for optical buffering and signal processing.
• Graphene's unique electronic properties offer tunable control over plasmonic devices.

Purpose of the Study:

• To propose and analyze a novel plasmonic waveguide structure for realizing dual-channel slow surface plasmon polaritons.
• To investigate the tunability of the slow light properties via gate voltage.
• To assess the potential of the proposed waveguide for practical slow light device applications.

Main Methods:

• Design of a plasmonic waveguide using single-layer graphene, silica dielectric, and silicon grating substrate.
• Introduction of dual periodic structures with defects to create two distinct slow light channels.
• Application of the Bragg equation to match structure parameters for specific operating wavelengths (9369.1 nm and 7138.2 nm).
• Analysis of structure parameter influence on slow light effects and calculation of the normalized delay bandwidth product (NDBP).
• Demonstration of linear blueshift and stable slow light performance by adjusting the gate voltage.

Main Results:

• Successful realization of a dual-channel slow surface plasmon polaritons waveguide.
• Achieved operation at wavelengths of 9369.1 nm (32 THz) and 7138.2 nm (42 THz).
• Maximum NDBP value of 7.38 was obtained.
• Demonstrated significant linear blueshift by gate voltage tuning.
• Observed stable slow light performance with average NDBP values of 4.5 and 4.4.

Conclusions:

• The proposed graphene-based plasmonic waveguide effectively supports dual-channel slow surface plasmon polaritons.
• The device exhibits flexible tunability through gate voltage, enabling dynamic control of slow light properties.
• The stable performance and tunable nature of the waveguide make it a promising platform for developing advanced slow light devices.