Taming Friedrich-Wintgen Interference in a Resonant Metasurface: Vortex Laser Emitting at an On-Demand Tilted Angle

Area of Science:

• Optics and Photonics
• Metamaterials
• Non-Hermitian Physics

Background:

• Friedrich-Wintgen (FW) interference enables loss exchange between resonances in non-Hermitian systems.
• This mechanism can transform radiating waves into bound states in the continuum (BICs) by eliminating losses.
• Tailoring FW-BICs offers new possibilities for controlling light-matter interactions.

Purpose of the Study:

• To propose and experimentally demonstrate a novel concept for tailoring FW-BICs with polarization singularity.
• To achieve on-demand control over wavevectors for FW-BIC manipulation.
• To explore the potential of engineered FW-BICs for advanced optical functionalities.

Main Methods:

• Fabrication of optical metasurfaces using hybrid organic-inorganic halide perovskite.
• Experimental demonstration of Friedrich-Wintgen interference in the metasurface.
• Characterization of polarization singularity and lasing emission properties.
• Analysis of momentum space and emission directionality.

Main Results:

• Successful tailoring of FW-BICs with on-demand polarization singularity in optical metasurfaces.
• Observation of lasing emission from the engineered FW-BICs.
• Demonstration of highly directional emission at oblique angles.
• Characterization of a polarization vortex in momentum space.

Conclusions:

• The proposed concept enables precise control over FW-BICs and their polarization properties.
• Engineered FW-BICs with polarization singularity can generate steerable coherent emission.
• This work opens avenues for applications in optical communication, imaging, and data storage.