A broadband achromatic metalens array for integral imaging in the visible

Abstract

Integral imaging is a promising three-dimensional (3D) imaging technique that captures and reconstructs light field information. Microlens arrays are usually used for the reconstruction process to display 3D scenes to the viewer. However, the inherent chromatic aberration of the microlens array reduces the viewing quality, and thus, broadband achromatic imaging remains a challenge for integral imaging. Here, we realize a silicon nitride metalens array in the visible region that can be used to reconstruct 3D optical scenes in the achromatic integral imaging for white light. The metalens array contains 60 × 60 polarization-insensitive metalenses with nearly diffraction-limited focusing. The nanoposts in each high-efficiency (measured as 47% on average) metalens are delicately designed with zero effective material dispersion and an effective achromatic refractive index distribution from 430 to 780 nm. In addition, such an achromatic metalens array is composed of only a single silicon nitride layer with an ultrathin thickness of 400 nm, making the array suitable for on-chip hybrid-CMOS integration and the parallel manipulation of optoelectronic information. We expect these findings to provide possibilities for full-color and aberration-free integral imaging, and we envision that the proposed approach may be potentially applicable in the fields of high-power microlithography, high-precision wavefront sensors, virtual/augmented reality and 3D imaging.

Liquid crystal integrated metalens with tunable chromatic aberration

“…23,24 To solve this problem, mechanical scanning along the optical path is required to capture images at different frequencies, 25 which makes the detection and analysis complicated and time-consuming. More recently, inspired by achromatic metalens designs in the visible and near-IR range, [26][27][28][29][30] broadband achromatic focusing has been realized in the THz regime via dispersive phase compensation from C-shape silicon micropillar arrays. 31 By contrast, for spectrographic and tomographic applications, 32,33 large chromatism is favored to separate focal spots of different frequencies spatially without crosstalk.…”

Imaging based on metalenses

“…10(a). Besides, the ability to evaluate the depths of objects and to measure the relative speed can be achieved owing to the light [103]. (d) Upper panel: reconstructed images in the case that the number "3" is closer to the central depth plane than the letter "D", and they are focused on "3" plane.…”

“…Lower panel: reconstructed images in the case that the number "3" is closer to the central depth plane than the letter "D", and they are focused on "D" plane. Scale bar: 100 μm [103]. (e) Schematic of the metalens depth sensor estimating depth by mimicking the jumping spider.…”

“…Distinguish slightly from the light field camera mentioned above, three-dimensional scene is encoded with algorithms and then image with depth information is reconstructed in the progress of integral imaging displays with the designed silicon nitride metalens array for white light in Fig. 10(d) [103]. The metalens array can realize the diffraction-limited focusing for different polarizations and be integrated on the chip to achieve the optoelectronic information.…”

Wide‐viewing integral imaging display using rectangular light sources

“…Integral imaging display presents three‐dimensional (3D) images with continuous viewpoints, full color, and parallax 1–8 . It has been adopted to realize a dual‐view 3D display which presents different 3D images in the left and right viewing directions 9–12 .…”