Nanoplasmonic Pyramidal Metamaterial Absorber at Optical Frequencies

A pyramidal shaped metamaterial absorber (PMA) supports broadband and polarization independent resonant absorption at optical frequencies. The PMA is designed by stack of alternative plasmonic/dielectric multilayers. These nanoplasmonic pyramids offers resonant absorption characteristics at wide range of optical frequencies. The optimized PMA structure allows 76% spectral absorption and nearly perfect absorption (over 90%) at several bands between range of 400 nm – 1500 nm wavelength. These light absorption characteristics of PMA are useful for photodetection, thermal imaging, thermal emitters, and solar cells etc.

Polarization-independent broadband achromatic metalens in the mid-infrared (3-5 μm) region

With superior capabilities for light manipulation and wavefront shaping, the metasurface recently has caught growing attention. However, the presence of chromatic aberration hinders metasurfaces, especially metalenses, from wider applications. Here, we design a polarization-independent broadband achromatic focusing metalens in the mid-infrared region, which covers continuous bands in 3-5 μm. Numerical simulation shows that different wavelengths can be focused to the same plane with a nearly diffraction-limited resolution, and can achieve an average focusing efficiency of nearly 70% in the whole bandwidth. We expect that our approach can underpin the development of integrated and mid-infrared imaging and detection.