Ultraviolet Chiral Lasing in In-Plane Photonic Crystal via Quasi-Bound State in the Continuum

Area of Science:

• Photonics
• Quantum Optics
• Materials Science

Background:

• Chiral lasers with circularly polarized emissions are vital for quantum optics, display technologies, and biosensing.
• UV chiral lasers are particularly important for sensitive biomolecule detection via circular dichroism.
• Current challenges include fabricating compact and highly chiral UV lasers due to material and design complexities.

Purpose of the Study:

• To demonstrate a novel UV chiral laser based on quasi-bound states in the continuum (quasi-BIC).
• To achieve strong intrinsic chirality in a UV laser without complex fabrication techniques like slanted structures.
• To provide a scalable and material-compatible platform for chiral laser sources.

Main Methods:

• Utilized a Gallium Nitride (GaN) nanopillar array.
• Introduced in-plane asymmetry using semielliptical notches.
• Achieved out-of-plane asymmetry by removing the index-matching superstrate.

Main Results:

• Demonstrated a UV chiral laser with strong intrinsic chirality.
• Achieved highly circularly polarized lasing with a degree of circular polarization (DOCP) of 0.95.
• Observed a narrow linewidth of 0.18 nm and a low beam divergence of 1.80°.

Conclusions:

• The developed quasi-BIC UV chiral laser offers a simple yet effective approach to intrinsic chirality.
• This scalable and material-compatible platform advances chiral laser sources for various applications.
• Paves the way for enhanced quantum optics, photonic devices, and enantioselective sensing.