Ultrawideband graphene three-port circulator for THz region

Area of Science:

• Terahertz (THz) technology
• Condensed matter physics
• Nanophotonics

Background:

• Circulators are essential components in microwave and optical systems for signal routing.
• Traditional circulators often face limitations in size, bandwidth, and integration with semiconductor technologies.
• Graphene's unique tunable electronic properties offer potential for novel device functionalities.

Purpose of the Study:

• To design and theoretically validate a novel graphene-based circulator operating at terahertz frequencies.
• To investigate the influence of magnetization and device parameters on circulator performance.
• To demonstrate a wide operational bandwidth, high isolation, and low insertion loss.

Main Methods:

• Utilizing a concave graphene junction integrated with three waveguides on SiO2/Si substrate.
• Exploiting the non-symmetric conductivity tensor of magnetized graphene for circulation.
• Employing full-wave electromagnetic computations to validate theoretical predictions.

Main Results:

• Demonstrated a circulator with a 42% frequency band (2.75–4.2 THz).
• Achieved isolation greater than 17 dB and insertion losses below 2 dB.
• Identified optimal device parameters for maximizing performance and minimizing the required DC magnetic field.

Conclusions:

• The proposed graphene circulator offers a promising solution for THz applications.
• The device's performance is highly dependent on graphene's physical and electromagnetic properties.
• This work paves the way for compact, high-performance circulators integrated with semiconductor platforms.