In general, a virtual reality head-mounted display (VR-HMD) consists of a display, a light source, and a coupler. A coupler using a nanograting (Gr) leads to improvements in the performance and compactification of the device. To date, many research studies on compact high-performance HMDs using dielectric Gr couplers have been reported. However, to create an ultracompact highperformance HMD, a dual-Gr sample must be prepared as a new coupler. In this work, an attempt has been made to build a model of an HMD using dual Gr samples and their optimization for ray-tracing simulation and their fabrication process has been discussed.