Band-tunable achromatic metalens based on phase change material

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Achromatic metalenses offer miniaturization for broadband imaging but typically have fixed spectral bands.
• The inability to actively tune the achromatic band limits their application in dynamic optical systems.

Purpose of the Study:

• To develop a band-tunable achromatic metalens.
• To demonstrate reversible switching of achromatic bands using phase-change materials.

Main Methods:

• Fabrication of a bilayer metalens utilizing antimony trisulfide (Sb2S3) with contrasting amorphous and crystalline states.
• Characterization of the metalens' optical performance and band-switching capabilities.

Main Results:

• Reversible switching of achromatic bands between the visible red spectrum (650-830 nm) and near-infrared spectrum (830-1100 nm).
• Achieved average focusing efficiencies of over 35% and 55% in the respective bands.
• Maintained diffraction-limited focusing performance across switched bands.

Conclusions:

• The proposed metalens presents a novel approach for ultrabroadband achromatic focusing with tunable spectral ranges.
• The design enables multifunctional applications, combining achromatic and diffractive focusing.
• Potential applications include tunable displays, advanced detectors, and multifunctional optical devices.