Gain-assisted critical coupling for high-performance coherent perfect absorbers

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Balanced radiation and absorption are crucial for coherent perfect light absorption in active optical devices.
• This balance is known as the critical coupling condition, essential for device performance.

Purpose of the Study:

• To propose a novel gain-assisted method for achieving critical coupling without structural modifications.
• To demonstrate precise control over light absorption and device functionality through optical pumping.

Main Methods:

• Utilizing internal gain media within a coherent absorber.
• Tuning optical pumping density to achieve critical coupling.
• Numerical simulation of a surface-plasmon resonance grating with a gain layer.

Main Results:

• Exact access to critical coupling conditions was demonstrated by tuning optical pumping density.
• Arbitrarily high coherent signal extinction was achieved.
• The gain tuning enabled switching functionality to a lossless beam splitter.

Conclusions:

• The proposed gain-assisted method offers a versatile approach to control coherent perfect light absorption.
• This technique allows for dynamic tuning of optical absorber properties and device functionality.