Taming Friedrich-Wintgen interference in resonant metasurface: vortex laser emitting at on-demand tilted-angle

TL;DR

This paper demonstrates a novel method to control Friedrich-Wintgen interference in optical metasurfaces, enabling on-demand tilted-angle vortex laser emission with polarization singularities for advanced optical applications.

Contribution

It introduces a new approach to engineer Friedrich-Wintgen bound states in the continuum as polarization singularities in metasurfaces, demonstrated with organic-inorganic halide perovskites.

Findings

Achieved highly directional laser emission at oblique angles.

Generated polarization vortex in momentum space.

Enabled steerable coherent emission with tailored polarization patterns.

Abstract

Friedrich-Wintgen (FW) interference is an atypical coupling mechanism that grants loss exchange between leaky resonances in non-Hermitian classical and quantum systems. Intriguingly, such an mechanism makes it possible for destructive interference scenario in which a radiating wave becomes a bound state in the continuum (BIC) by giving away all of its losses. Here we propose and demonstrate experimentally an original concept to tailor FW-BICs as polarization singularity at on-demand wavevectors in optical metasurface. As a proof-of-concept, using hybrid organic-inorganic halide perovskite as active material, we empower this novel polarization singularity to obtain lasing emission exhibiting both highly directional emission at oblique angles and polarization vortex in momentum space. Our results pave the way to steerable coherent emission with tailored polarization pattern for applications in optical communication/manipulation in free-space, high-resolution imaging /focusing and data storage.