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13 October 2016

VerLASE awarded US patent on 2D materials enabling downconversion of InGaN-based blue/violet emitters to any color

VerLASE Technologies LLC of Bridgewater, NJ, USA (a spin-off from technology development firm Versatilis LLC of Shelburne, VT, USA) says that the US Patent Office had awarded it US Patent No. 9,431,794 on the use of 2D materials to grow semiconductor structures that can downconvert InGaN-based blue/violet emitters into any color in the visible part of the spectrum, obviating the use of phosphors and quantum dots (QDs). The patent expands the firm's IP portfolio to six US patents now issued, with others pending, covering the use of quantum wells (QWs) and novel resonators to make color-converting chiplets principally for the emerging augmented reality (AR) market.

In AR architectures, optical or holographic waveguides can now superimpose a microdisplay image onto a user's field of view, or an image can even be scanned directly onto a user's retina, but forming such micro-images bright enough to see against a bright daylight background in full color and high resolution remains a significant challenge. The organic light-emitting diode (OLED) microdisplays used today principally in a self-contained virtual reality (VR) environment simply cannot meet requirements for such next-generation AR microdisplays; there are no good solutions to efficiently render such micro-images at high enough brightness, at high resolution and in full color.

The new patent builds on the firm's prior patents to show how II-VI and other semiconductor materials can be grown in the very difficult-to-achieve wurtzite crystal phase by using certain 2D materials as templates, a feat the firm had also shown experimentally, claiming to be the first group to have done so. Such II-VI films have hitherto been commonly grown in the less stable zincblende phase with high defect densities limiting their broader use.

Wurtzite phase makes possible robust, high-quality, near-defect-free QWs used in the firm's Chromover color down-conversion technology. Using a novel resonator design, Chromover can be designed to efficiently emit omnidirectional or directional spontaneous LED light, the latter in a narrow, low-├ętendue cone angle; or, if excited by a laser diode, to lase as an optically pumped vertical-cavity surface-emitting laser (VCSEL). Spectral properties can also be tailored to a degree, with some control of coherence to mitigate speckle (a significant problem in projecting images with lasers).

A single Chromover chiplet can be pixelated and support multiple colors (RGB), forming a color-converting layer for emerging InGaN-based microLED displays. Such microLED displays are suited to AR, being far brighter, more efficient and much longer lived than the OLED microdisplays used in VR. They require efficient color conversion, however, but the traditional phosphors and QDs used for color with LEDs are not practical. Moreover, the diffractive or holographic waveguide optics used in the leading AR architectures are highly sensitive to input angle and spectral width, making imperative some directional and spectral control of the input source light.

"This is a key step to realizing the vision of untethered, stylish glasses that can project high-resolution, full-color images onto your field of view with long battery life," says inventor & chief technology officer Ajay Jain. "All the manufacturing processes are readily available, commercially scalable, and can be outsourced," he adds. VerLASE has been working with leading players in the VR/AR space to better define market requirements.

See related items:

VerLASE extends patent portfolio in 2D semiconductor materials for light sources

Tags: 2D Nanocrystals microLED

Visit: www.verlase.com

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