Wideband tunable mid-infrared cross polarization converter using rectangle-shape perforated graphene

Area of Science:

• Optoelectronics
• Plasmonics
• Materials Science

Background:

• Graphene exhibits strong plasmonic properties and electrostatic tunability, making it suitable for infrared optoelectronic devices.
• Controlling light polarization is crucial for various mid-infrared applications.

Purpose of the Study:

• To propose and demonstrate a wideband tunable cross polarization converter using periodically perforated graphene.
• To investigate the device's performance in terms of bandwidth, conversion ratio, and angular stability.

Main Methods:

• Fabrication of a polarization converter comprising a metal ground plane, insulator layer, and periodically perforated graphene sheet.
• Utilizing superimposed localized surface plasmon modes for polarization conversion.
• Electrostatic tuning of graphene's Fermi energy to control performance.

Main Results:

• Achieved transformation of linear polarization to cross polarization over a wide bandwidth (~5% of central frequency at 46.8 THz).
• Demonstrated a peak conversion ratio exceeding 90%.
• Maintained polarization conversion performance for incident angles up to 50°.

Conclusions:

• The proposed periodically perforated graphene device functions as an effective mid-infrared wideband tunable cross polarization converter.
• The device's performance is robust against wide incident angles and highly tunable via electrostatic gating.
• This work offers a promising platform for manipulating light polarization in mid-infrared applications.