Surface relief coupled grating design for near-eye display

As the most important optical component in a near-eye display system, the performance of a coupling grating directly determines the imaging quality of the final display system. In order to improve the diffraction efficiency and field of view (FOV) of the coupling device, this study proposes a novel surface relief coupling grating. The structural parameters of the surface relief coupled grating are simulated and calculated by using the finite-element analysis method. The simulation results show that the diffraction efficiency of the coupling grating can reach more than 99.5%. Compared with the traditional rectangular tilted grating, the diffraction efficiency has increased by 6.4%, and the full width at half-maximum of the incident angle has increased by 4°, which proves that the structure has higher diffraction efficiency and a larger FOV. Furthermore, the surface relief coupling grating is insensitive to operating conditions and processing errors, fully meeting the processability requirements. Therefore, this new type of surface relief coupling grating can replace traditional coupling gratings and is expected to become a key coupling component in the next generation of near-eye display systems.