Metalenses with Polarization-Insensitive Adaptive Nano-Antennas

Metalens research has made major advances in recent years. These advances rely on the simple design principle of arranging meta-atoms in regular arrays to create an arbitrary phase and polarization profile. Unfortunately, the concept of equally spaced meta-atoms reaches its limit for high deflection angles where the deflection efficiency decreases. The efficiency can be increased using nano-antennas with multiple elements, but their polarization sensitivity hinders their application in metalenses. Here, it is shown that by designing polarization-insensitive dimer nano-antennas and abandoning the principle of equally spaced unit cells, polarization-insensitive ultrahigh numerical aperture (NA = 1.48) oil-immersion operation with an efficiency of 42% can be demonstrated. This represents a significant improvement on other polarization-insensitive designs at visible wavelength. This single layer metalens is used to replace a conventional objective lens and demonstrates the confocal scanning microscopic imaging of a grating with a period of 300 nm at 532 nm operating wavelength. Overall, the results experimentally demonstrate a novel design concept that further improves metalens performance.

Automated summary

Metalens research has made significant advances by designing polarization-insensitive dimer nano-antennas, which enables polarization-insensitive ultrahigh numerical aperture oil-immersion operation. This technology greatly improves efficiency at visible wavelength and has been successfully applied in confocal scanning microscopic imaging.