Full Asymmetric Radiation Control Through Multi-Channel Bound States in the Continuum.

Area of Science:

• Photonics
• Optical Physics
• Materials Science

Background:

• Bound states in the continuum (BICs) offer extreme light confinement due to theoretically infinite quality factors.
• Breaking symmetry in BIC systems allows asymmetric radiation, but control over counter-propagating beams is limited.
• Current methods struggle with arbitrary control of amplitude ratio and phase difference for beam manipulation in a single half-space.

Purpose of the Study:

• To investigate BICs in the superwavelength regime with multiple diffraction orders.
• To achieve comprehensive and continuous control over unidirectional guided resonances (UGRs).
• To demonstrate full tunability of directionality and relative phase difference between co-propagating beams.

Main Methods:

• Systematic investigation of far-field polarization states and topological properties of diffraction channels.
• Engineering photonic structures to support two co-propagating diffraction orders in the same half-space.
• Analysis of BICs in the superwavelength regime enabling multiple diffraction orders.

Main Results:

• Demonstrated comprehensive and continuous control over unidirectional guided resonances (UGRs).
• Achieved full tunability of directionality (from -1 to 1) between co-propagating beams.
• Enabled full tunability of the relative phase difference (from -π to π) between these beams.

Conclusions:

• Engineered BIC configuration allows versatile manipulation of multiple beams radiating into a specific direction.
• This control over co-propagating beams opens new avenues for advanced photonic applications.
• The findings advance the field of light confinement and beam manipulation in photonic structures.