Optical radiation manipulation via topological polarization singularities.

Area of Science:

• Photonics
• Condensed Matter Physics
• Optical Singularities

Background:

• Bound states in the continuum (BICs) and unidirectional guided resonances (UGRs) are phenomena controllable via topological polarization singularities (TPSs).
• Conventional methods generate BICs using vortex polarization singularities (V points) with identical topological charges for upward and downward radiation.

Purpose of the Study:

• To propose a new class of off-Γ hetero-topological charge BICs.
• To investigate the formation of quasi-UGRs using circular polarization states (C points).
• To demonstrate control of light radiation by manipulating TPSs.

Main Methods:

• Theoretical proposal of off-Γ hetero-topological charge BICs.
• Utilizing a structure with inversion symmetry.
• Analysis of V points with opposite topological charges.
• Formation of quasi-UGRs via C points in upward or downward radiation.

Main Results:

• Successful construction of off-Γ hetero-topological charge BICs from V points with opposite charges.
• Formation of quasi-UGRs by C points incompletely blocking radiation.
• Demonstration that manipulating TPSs enables control over light radiation.

Conclusions:

• Provides novel insights into generating off-Γ hetero-topological charge BICs.
• Highlights the critical role of manipulating TPSs in light-matter interactions.
• Offers a new paradigm for controlling optical phenomena through topological singularities.