Monolayer-graphene-based perfect absorption structures in the near infrared

Area of Science:

• Photonics and Nanotechnology
• Optoelectronics
• Materials Science

Background:

• Subwavelength optical absorbers are crucial for optoelectronic devices.
• Graphene's unique properties offer potential for novel optical applications.
• Achieving perfect absorption at specific wavelengths is a key challenge.

Purpose of the Study:

• To analyze and experimentally demonstrate subwavelength perfect optical absorbers based on monolayer graphene.
• To investigate the mechanism of perfect absorption through critical coupling and guided mode resonance.
• To explore the influence of geometrical parameters and angular response on absorption performance.

Main Methods:

• Theoretical analysis of critical coupling and guided mode resonance.
• Fabrication of a two-dimensional periodic structure using monolayer graphene.
• Experimental characterization of optical absorption spectra.
• Numerical simulations to analyze geometrical parameter and angular dependence.

Main Results:

• Demonstrated peak absorption exceeding 99% at a wavelength of 1526.5 nm.
• Achieved a narrow full-width at half maximum (FWHM) of approximately 18 nm.
• Experimental results showed excellent agreement with simulation predictions.
• Detailed analysis of structural parameter and angular response effects was performed.

Conclusions:

• Monolayer graphene-based subwavelength structures can achieve near-perfect optical absorption.
• The critical coupling mechanism via guided mode resonance is effective for perfect absorption.
• The demonstrated structures hold significant promise for developing advanced photodetectors and modulators.