Gain-assisted critical coupling for enhanced optical absorption in graphene

Area of Science:

• Nanophotonics
• Materials Science
• Quantum Optics

Background:

• Two-dimensional (2D) materials exhibit enhanced optical absorption, making them promising for nanophotonics.
• Achieving critical coupling in such systems is key to maximizing light absorption.
• Undoped monolayer graphene offers unique optoelectronic properties for near-infrared applications.

Purpose of the Study:

• To present a novel gain-assisted method for achieving critical coupling in graphene.
• To demonstrate maximum optical absorption in undoped monolayer graphene within the near-infrared spectrum.
• To provide a versatile approach for manipulating light-matter interactions in 2D materials.

Main Methods:

• Utilizing a two-port system with a photonic crystal slab loaded with graphene.
• Introducing a gain medium to precisely tune the dissipative and radiation rates.
• Achieving critical coupling by matching these rates without altering the device structure.

Main Results:

• Demonstrated critical coupling and maximum absorption in undoped monolayer graphene.
• Showcased the ability to tune critical coupling absorption across a wide wavelength range.
• Confirmed that the gain coefficient adjustment is effective for various coupling configurations.

Conclusions:

• The gain-assisted method offers a powerful strategy for enhancing light absorption in 2D materials.
• This approach enables the design of ultra-compact and high-performance 2D material optical devices.
• The findings open new avenues for manipulating light-matter interactions in nanophotonic systems.