Third harmonic generation from graphene lying on different substrates: optical-phonon resonances and interference...

Area of Science:

• Nonlinear optics
• Condensed matter physics
• Materials science

Background:

• Graphene exhibits nonlinear optical properties, enabling applications like frequency mixing.
• Third harmonic generation (THG) is a key nonlinear optical process.
• Substrate interactions can significantly modify graphene's optical response.

Purpose of the Study:

• To theoretically investigate third harmonic generation (THG) in graphene on various dielectric substrates.
• To explore methods for enhancing THG intensity in graphene.
• To analyze the influence of substrate properties on graphene's nonlinear optical response.

Main Methods:

• Theoretical modeling of THG in graphene.
• Analysis of graphene on dispersionless and polar dielectric substrates.
• Consideration of substrates with and without back-side metallization.

Main Results:

• THG intensity from graphene on substrates can be orders of magnitude higher than in isolated graphene.
• Substrate effects, such as LO-phonon resonances in polar dielectrics and interference in metalized substrates, boost THG.
• Polar dielectric substrates can lead to a nearly frequency-independent THG response.

Conclusions:

• Substrate engineering offers a powerful route to enhance graphene-based nonlinear optical devices.
• Graphene's nonlinear optical properties can be tailored for efficient frequency multiplication.
• The findings support the development of graphene frequency multipliers for microwave to infrared applications.