Abstract— Near‐to‐eye (NTE) displays are generally systems where the imaging optics of a microdisplay is brought close to the eye, like a magnifying glass. In portable NTE terminals, the challenges are in achieving low power consumption as well as low weight and small size. Part of the problem is related to the microdisplay, but the optics also plays a major role. A study on how diffractive optical elements (DOEs) on planar waveguides can be used to miniaturize the optics of NTE displays is presented and the performance of the system is analyzed.

Diffractive slanted gratings are manufactured onto plastic light guides using a high refractive index material and UV replication technology. We show that the manufacturing of such components is possible in large quantities. The applications of the slanted gratings are a high efficiency light in- and outcoupling with plastic light guides. We also show that it is possible to control which outcoupling diffraction order, reflective or transmissive, is dominating and hence to maximize the light power to one direction.

Diffractive Optical Elements (DOE's) on planar waveguides can be used to miniaturize the optics of a Virtual Reality Display (VRD). A biocular VRD that uses the diffractive planar waveguide as an Exit Pupil Expander (EPE) is ergonomically excellent but suffers from low efficiency and from uneven light distribution in the perceived virtual image. Using novel diffractive structures the efficiency of the system can be dramatically improved and an excellent performance over a wide Field of View (FOV) can be achieved. In this paper it is shown that with deep slanted grating profiles more than 90% diffraction efficiency can be reached and that etendue of the system is improved. It is also shown that the binary sub‐wavelength gratings with a proper groove shape are not polarization sensitive. The performance of the EPE plate can be optimized using the filling ratio, the grating depth and the slanting angle as tuning parameters. The volume production methods of the deep slanted grating structures are discussed and some experimental results are shown.

Power-efficiency demands on mobile communications device displays have become severe with the emergence of full-video-capable cellular phones and mobile telephony services such as third-generation (3G) networks. The display is the main culprit for power consumption in the mobile-phone user interface and the backlight unit (BLU) of commonly used active-matrix liquid-crystal displays (AMLCDs) is the main power drain in the display. One way of reducing the power dissipation of a mobile liquid-crystal display is to efficiently distribute and outcouple the light available in the backlight unit to direct the primary wavelength bands in a spectrum-specific fashion through the respective color subpixels. This paper describes a diffractive-optics approach for a novel backlight unit to realize this goal. A model grating structure was fabricated and the distribution of outcoupled light was studied. The results verify that the new BLU concept based on an array of spectrum-specific gratings is feasible.

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