Dynamic selection of visible wavelengths using resonant TiO₂ nanostructures

Area of Science:

• Nanophotonics
• Metasurfaces
• Optical Engineering

Background:

• All-dielectric nanoarrays exhibit tunable optical properties via geometrical parameters, but these are fixed post-fabrication.
• Existing nanoresonators lack dynamic tunability, limiting applications requiring adjustable optical responses.

Purpose of the Study:

• To develop robust, dynamically tunable all-dielectric nanoresonators for controllable and reproducible color filtering.
• To demonstrate reversible spectral tuning of nanoresonator optical properties through mechanical strain.

Main Methods:

• Fabrication of titanium dioxide (TiO2) nanodiscs embedded in a stretchable polydimethylsiloxane (PDMS) membrane.
• Utilizing Mie magnetic and electric dipole resonances hybridized with lattice modes for narrow spectral response.
• Employing mechanical stretching of the PDMS membrane to alter the nanodisc pitch and tune resonance frequencies.
• Creating an optically asymmetric structure to minimize Rayleigh anomaly diffraction effects.

Main Results:

• Achieved sharp, frequency-tunable resonances in the visible spectrum.
• Demonstrated dynamic tunability of spectral response by mechanically stretching the metasurface.
• Successfully controlled, reversed, and reproduced color filtering properties.

Conclusions:

• The proposed design enables dynamic control over optical properties of all-dielectric nanoresonators.
• Mechanical strain offers a viable method for real-time spectral tuning of nanophotonic devices.
• This work paves the way for advanced tunable optical filters and metasurfaces.