Mid-infrared chiral planar metasurface thermal emitters based on quasiguided modes

Area of Science:

• Optics and Photonics
• Materials Science
• Spectroscopy

Background:

• Infrared circularly polarized emission is vital for vibrational circular dichroism (CD) spectroscopy.
• Fabricating 3D chiral structures for such applications presents significant challenges.

Purpose of the Study:

• To design a planar chiral all-dielectric metasurface for narrowband, high CD chiral thermal emission in the mid-infrared (MIR) region.
• To overcome fabrication limitations of traditional 3D chiral structures.

Main Methods:

• Utilized quasiguided modes and in-plane displacement perturbations.
• Employed Brillouin zone folding and symmetry breaking for chiral emission.
• Applied theoretical analysis, temporal coupled-mode theory, and Jones matrix for reflection characteristics.
• Performed multipole expansion analysis to identify dominant resonances.

Main Results:

• Achieved narrowband, high CD chiral thermal emission sources.
• Demonstrated selective emission of right-handed circularly polarized light with CD values close to ±1.
• Verified robustness against structural parameter and incident angle variations through simulations.

Conclusions:

• The planar metasurface design offers a viable solution for MIR chiral sensing and efficient thermal emission.
• The proposed structure exhibits high Q factors, narrow bandwidths, and planar fabrication compatibility.
• This work provides significant potential for applications in advanced optical sensing and emission technologies.