We design and fabricate a 60 × 60 GaN based achromatic meta-lens array to capture multidimensional optical information of the scene. The working wavelength is from 400 nm to 660 nm which covers the entire visible light range. The highest efficiency of single metalens can be up to 74% at a wavelength of 420 nm, while the average efficiency is approximately 39% over the whole working bandwidth. The light field images and the depth information of objects can be determined by reorganizing the patches of sub-images and calculating the disparity of neighboring sub-images, respectively. The depth information can be used to optimize the patch sizes to render the all-in-focus image without artifacts. Our work provides several advantages associated with light field imaging: elimination of chromatic aberration, polarization selectivity and compatibility of the semiconductor process.
Optical meta-devices using meta-surfaces which composed of artificial nanostructures are able to manipulate the electromagnetic phase and amplitude at will. The great advantages of meta-devices are their new properties, lighter weight, small size, high efficiency, better performance, broadband operation, lower energy consumption, and CMOS compatibility for mass production. Given the demand for photonics, many optical meta-devices for the application and control of incident light are being quickly developed for beam deflection and reflection, polarization control and analysis, holography, second-harmonic generation, laser, tunability, imaging, absorption, focusing of light, multiplex color routing and light-field sensing. The design, fabrication and application of the novel optical meta-devices are reported in this talk.
Metalenses have great ability in light focusing and can be tailored to exhibit varied functionalities for ultrathin optical applications. Here, we demonstrate a GaN metalens array which can be regarded as a light shaping generator for the structured light generation. The metalens array consists of 60 x 60 metalenses which can project a 42 cm x 42 cm light spots area at the distance of 1.5 M. The distance can be estimated by identifying the deformation of light spot distribution. The advantages of this metadevice is light weight, small, ultrathin, durable and easy to compact with other devices. Our design provides a new avenue for the structured light applications such as distance sensing and 3D environmental construction.
Here we demonstrated a GaN metalens array to project a light spots array which can be a light shape generator in the structure light applications. The advantages of this metadevice is light weight, small, ultrathin, durable and easy to compact with other device. The light spot size is a function with the distance of detector. A metalens array which arranged by the single metalens diameter is 20 μm projected a light spots array whose diameter of single light spot is 2.22 um in average at the distance is 150 cm far away and. Our design provides a new avenue for the structure light application such as distance sensing and 3D environmental construction.
The toroidal dipole moments of natural molecules are hard to be detected so the artificial toroidal materials made by metamaterial attract more attentions. Metamaterial, the sub-wavelength artificial structures, can modulate reflection or transmission of light. The toroidal metamaterial can not only amplify the toroidal moment but also repress the electric and magnetic dipole so it can be used to study the properties of toroidal dipole moment. However, there are many limitations for the experiments, such as the lateral light is necessary to excite the toroidal response. Most of the toroidal dipole moments oscillate perpendicularly to the substrate, therefore it is difficult to couple it with other dipole moments and could be only excited in the microwave region. In this paper, we design a toroidal metamaterial consisting of dumbbell-shaped aperture and vertical split ring resonator (VSRR) vertically. The toroidal dipole moment of our metamaterial is excited in the optical region. The arrangement of our nanostructures is vertical instead of planar annular arrangement to reduce the size of the unit cell and increase the density of the toroidal dipole moment. Moreover, the direction of toroidal dipole moment is parallel to the substrate which can be used for the study of the coupling effect with other kinds of dipolar moments.
Toroidal dipole moments, the third kind of fundamental dipole moment, have unusual electromagnetic properties
different from the electric and magnetic multipoles. We fabricate a new type of 3D plasmonic toroidal metamaterial by
using mutual coupling between dumbbell-shaped gold apertures with vertical split-ring resonators (VSRRs) at optical
frequency. The radiated power of multipole moments are calculated and analyzed to improve the meta-system is
dominated by the toroidal dipole moment. This result paves a way for practical application on metamaterial based
devices, such as biosensor and lasing spaser.