Absorption and amplification singularities in metasurface etalons with gain

Area of Science:

• Photonics
• Metamaterials
• Non-Hermitian Physics

Background:

• Passive reflective metasurfaces commonly achieve perfect absorption through singular scattering anomalies.
• Incorporating optical gain into metasurfaces offers potential for perfect amplification singularities, a less explored phenomenon.

Purpose of the Study:

• To analyze absorption and amplification singularities in plasmon antenna metasurface etalons with optical gain.
• To investigate the relationship between gain singularity conditions and perfect absorption conditions in metasurface etalons.

Main Methods:

• Utilized a simple transfer matrix model to analyze metasurface etalons.
• Employed frequency-dispersive models for gain media.
• Investigated Salisbury screen-type metasurface designs with plasmonic scatterers and a ground plate.

Main Results:

• Demonstrated that gain in metasurface etalons with both gain and loss can induce both perfect absorption and gain singularities.
• Showcased topological constraints governing the creation and annihilation of these singularities.
• Discussed limitations of time reversal symmetry arguments for relating gain poles to absorption zeros.

Conclusions:

• Gain-induced singularities offer new possibilities for active metasurface control.
• Findings have implications for non-Hermitian photonics and parity-time symmetric systems.
• Enables the development of dynamically controllable active metasurface pixels.