Abstract
With the rapid progress in computer science, including artificial intelligence, big data and cloud computing, full-space spot generation can be pivotal to many practical applications, such as facial recognition, motion detection, augmented reality, etc. These opportunities may be achieved by using diffractive optical elements (DOEs) or light detection and ranging (LIDAR). However, DOEs suffer from intrinsic limitations, such as demanding depth-controlled fabrication techniques, large thicknesses (more than the wavelength), Lambertian operation only in half space, etc. LIDAR nevertheless relies on complex and bulky scanning systems, which hinders the miniaturization of the spot generator. Here, inspired by a Lambertian scatterer, we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density, functioning in both transmission and reflection spaces. Over 4044 random spots are experimentally observed in the entire space, covering angles at nearly 90°. Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height, a nearly continuous phase coverage, a lightweight, flexible design, and low-heat dissipation. Thus, it may be mass produced by and integrated into existing semiconductor foundry designs. Our work opens important directions for emerging 3D recognition sensors, such as motion sensing, facial recognition, and other applications.
Highlights
The last decade has witnessed the emergence of novel technologies in computer science, ranging from big data, cloud computation, and machine learning to artificial intelligence
A point cloud refers to a set of data points in space, usually in three dimensions, Correspondence: Guoxing Zheng or Shaohua Yu or Junsuk Rho or Cheng-Wei Qiu 1School of Electronic Information, Wuhan University, Wuhan 430072, China 2NOEIC, State Key Laboratory of Optical Communication Technologies and Networks, Wuhan Research Institute of Posts and Telecommunications, Wuhan 430074, China Full list of author information is available at the end of the article
When a circularly polarized (CP) incident beam, say lefthanded CP light (LCP), shines on the metasurface, the output beam is divided into four parts: two sub-beams with the same handedness as the incident beam that experience no additional phase delay for both reflection and transmission, called co-polarized beams, and two with opposite handedness, i.e., right-handed CP light (RCP), which carry an additional phase delay of 2φ for both reflection and transmission, where φ is the orientation angle of the nanobrick, called cross-polarized beams
Summary
The last decade has witnessed the emergence of novel technologies in computer science, ranging from big data, cloud computation, and machine learning to artificial intelligence. These require increasingly powerful electronic or photonic devices to enable important applications, such as augmented reality, point-to-point medical electronics, and wearable devices. Once the scattered beams are captured by the sensors, the computer program can search the encoded information and determine the morphology of the detected objects This approach leads to several disadvantages, such as fabrication difficulty, the inherent limitation of spots spanning only a 2π space, Li et al Light: Science & Applications (2018)7:63 a b c yx φ
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