For a diffractive waveguide-based augmented reality display, we demonstrate a rapid and straightforward method to define the most compact layout of an exit pupil expander (EPE) from an analysis of diffractive optical elements in kspace. The idea is to consider all k-vectors coming from in-coupling to out-coupling areas according to the grating theory, and with the geometrical tracing of the EPE region to find the optimal layout. For a working wavelength of 532 nm, 40 degrees field of view display, our method is able to fit the layout into a circular shaped area with a minimal radius or to optimize for the minimal EPE area. Furthermore, a web-based interactive application demonstrating the EPE layout calculation is provided as a layout design tool.
Diffractive gratings, one of the most promising near-eye display designs, has been challenging to satisfy the essential features without making sacrifices in output efficiency or the direction of incidence due to the low diffraction efficiency of higher modes at normal incidence. Here, we propose dielectric metagratings that support light deflect to a larger angle with high efficiency within the field of view of 54 degrees. In this paper, through the proposed model of the eye-imaging system, we present optimal designs of metagratings for diffractive total internal reflection combiner or diffractive exit pupil expanders.