NEMS-tunable dielectric chiral metasurfaces

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Chiroptical responses in metasurfaces are crucial for optical polarization engineering.
• Plasmonic chiral metasurfaces suffer from inherent losses, limiting tunable responses.
• Low-loss dielectric chiral metasurfaces are sought after, especially electrically tunable ones for on-chip applications.

Purpose of the Study:

• To experimentally demonstrate nano-electromechanically tunable dielectric chiral metasurfaces.
• To achieve active control over reflective circular dichroism (CD) with low loss.
• To explore the potential for scalable optical polarization modulators.

Main Methods:

• Fabrication of dielectric chiral metasurfaces.
• Integration of nano-electromechanical systems (NEMS) for tuning.
• Characterization of reflective circular dichroism (CD) under varying electrical bias.

Main Results:

• Demonstrated a significant difference in reflection for orthogonal circular polarizations (>0.85 simulated, >0.45 experimental).
• Achieved continuous electrical tuning of CD from 0.45 to 0.01 using a 3V bias.
• Showcased low-loss performance characteristic of dielectric metasurfaces.

Conclusions:

• Nano-electromechanically tunable dielectric chiral metasurfaces offer a viable platform for active optical polarization control.
• These devices present a promising low-loss alternative to plasmonic counterparts.
• The demonstrated tunability and on-chip integration potential pave the way for scalable optical polarization modulators.