Beam manipulation for quantum dot light-emitting diode with an Ag grating and a phase-gradient metasurface

Improving optical coherence of light-emitting diodes by surface plasmons via shallow-etched conic pit array

We propose the coupling of multiple quantum wells and surface plasmons can improve coherence of light emitted from LED wafers, as evidenced herein by a shallow-etched conic pit array with evaporated Ag (V-Ag) on a GaN-based LED wafer. The improvement in spatial coherence is critically verified by angle-resolved spectra. The temporal coherence length of the V-Ag wafer is 1.4 times larger than that of the plain wafer. The coherence-enhanced wafer achieves anisotropic and deflective emission in micro area and at far field by diffraction. This research provides a novel perspective on research of plasmonic LEDs and a new straightforward architecture to acquire partially coherent light from LEDs.

A Review on Micro-LED Display Integrating Metasurface Structures

Micro-LED display technology has been considered a promising candidate for near-eye display applications owing to its superior performance, such as having high brightness, high resolution, and high contrast. However, the realization of polarized and high-efficiency light extraction from Micro-LED arrays is still a significant problem to be addressed. Recently, by exploiting the capability of metasurfaces in wavefront modulation, researchers have achieved many excellent results by integrating metasurface structures with Micro-LEDs, including improving the light extraction efficiency, controlling the emission angle to achieve directional emission, and obtaining polarized Micro-LEDs. In this paper, recent progressions on Micro-LEDs integrated with metasurface structures are reviewed in the above three aspects, and the similar applications of metasurface structures in organic LEDs, quantum dot LEDs, and perovskite LEDs are also summarized.

Dynamic adjustable metalens based on a stretchable substrate with a double-layer metal microstructure

Based on the impedance-matching theory, a double-layer metal structure dynamical focusing cylindrical metalens with a stretchable substrate was designed at the operation frequency of 0.1 THz. The diameter, initial focal length, and NA of the metalens were 80 mm, 40 mm, and 0.7, respectively. The transmission phase of the unit cell structures could cover 0-2π by changing the size of the metal bars, and then the different unit cells were spatially arranged as the designed phase profile for the metalens. When the stretching range of the substrate was about 100%-140%, the focal length changed from 39.3 mm to 85.5 mm, the dynamic focusing range was about 117.6% of the minimum focal length, and the focusing efficiency decreases from 49.2% to 27.9%. Then, by rearranging the unit cell structures, a dynamically adjustable bifocal metalens was numerically realized. Using the same stretching ratio, compared to a single focus metalens, the bifocal metalens can provide a larger focal length control range.