Giant Faraday and Kerr rotation with strained graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optics and Photonics

Background:

• Faraday and Kerr rotations describe polarization changes of electromagnetic waves interacting with magnetic fields in dielectric media.
• Recent experiments demonstrated significant Faraday rotation for terahertz waves in graphene on SiC substrates.
• Graphene's unique electronic properties offer potential for novel optical phenomena.

Purpose of the Study:

• To investigate the feasibility of inducing polarization rotation in graphene using in-plane strain fields instead of magnetic fields.
• To explore the potential of strained graphene for applications in optical devices like optical diodes.
• To theoretically predict the magnitude of Kerr rotation from a single strained graphene sheet.

Main Methods:

• Theoretical modeling of polarized electromagnetic wave interaction with strained graphene.
• Analysis of the pseudomagnetic field induced by in-plane strain in graphene.
• Calculation of polarization rotation angles for transmitted (Faraday) and reflected (Kerr) waves.

Main Results:

• In-plane strain fields in graphene can induce a pseudomagnetic field, leading to polarization rotation effects analogous to the Faraday and Kerr effects.
• A rotation of π/4 radians, suitable for an optical diode, can be achieved using two strained graphene sheets.
• A Kerr rotation of 1/4 radians is predicted from a single reflection off a strained graphene sheet.

Conclusions:

• Strain engineering in graphene provides an alternative to magnetic fields for controlling light polarization.
• Strained graphene sheets offer a promising platform for developing compact and efficient optical diodes and other photonic devices.
• The findings highlight the significant potential of graphene in advanced optical and optoelectronic applications.