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.
Increasing the nonlinear optical response at nanometer length scale is a very important issue due to the wide applications in various disciplines such as information science, bio-medicine and quantum computation technology. Second harmonic generation (SHG) arising from the metal nanostructures has provide a very powerful tool in studying the surface and interface properties of these materials. The SHG from various kinds of asymmetric geometric configurations such as V and L shape structures, imperfect nano-spheres, metal/insulator/metal multilayer structures, and planar split ring resonators have been proposed. However, all the previous studies in plasmonic nonlinear optical behavior rely on the enhancement of the electric field and seldom considered the magnetic field effect.
In this work, we present a vertical split ring resonator (SRR) based metamaterial to generate SHG. By adopting such a novel structure, both the electric and magnetic field will be significantly enhanced due to the localized surface plasmon resonance, hence the generation of the second-harmonic and its re-emission into the far field are dramatically increased several orders comparing with that of the planar SRR. We simulated and fabricated the reflective type vertical SRR, and optimized the aspect ratio to maximize the SHG signal. We further systematically studied the nonlinear optical response in the vertical SRR dimers and trimers and found that the gap distance between two SRRs plays a very important role in the SHG intensity. This work paves a new way in increasing the nonlinear transition quantum efficiency and provides a new insight in designing new nonlinear sources.