Broadband achromatic metalenses for imaging (Conference Presentation)

Most of information from the outside world is obtained through our eyes. Various colors make the world distinguishable and our life rich and colorful. To achieve the best imaging and displaying of our colorful world is the ultimate dream of human-being in all ages, which is also the main issue of Optics. Among different obstacles, the chromatic aberration directly brought from the intrinsic material property and phase accumulation at different wavelengths may be the most severe problem in a full-color optical system. Here, by using the IRU (integrated resonance unit elements) based metasurface, the first perfect achromatic lens at the visible region has been demonstrated, with only wavelength scale thickness that is quite desirable in the integrated Optics and daily life, such as in the cell-phone camera. Compared with the traditional (bulky) achromatic lenses or objectives, our achromatic metalens presents perfect achromatism in a continuous bandwidth rather than the traditional solution only suppressing the chromatic aberration at discrete wavelengths. In metalens field, our result is also far ahead in competition with other reported works. In comparison to the ordinary metalens, our broadband achromatic metalens demonstrates high transmission efficiency (about 60% at peak) in visible spectrum without chromatic aberration. The achieved continuous achromatism in visible region enables us to obtaining the first metalens-based full-color imaging. Recently, we demonstrate the full-color light-field imaging based on the broadband achromatic metalens array, which is considered as a signifcant progress for metalens imaging.