Fig. 1. Fabrication process of the proposed HWD.

Fig. 2. Experimental setups to (a) measure the diffraction efficiency of the slanted HPDLC grating and (b) test the electrically tunable performance of the HWD. The inset in (b) shows the orientation of the LC molecule under an electric field.

Fig. 3. Diffraction efficiency of the slanted HPDLC grating as a function of polarizer angle. 0° and 180° correspond to s polarization; 90° corresponds to p polarization.

Fig. 4. Display image of HWD and the background content.

Fig. 5. (a) Output intensity Io under different electric fields. (b) Diffraction efficiency of the slanted HPDLC grating under different electric fields.

Fig. 6. Display effect of the HWD under different ambient light and electric fields. (a) High ambient light and 0  V/μm; (b) low ambient light and 0  V/μm; (c) low ambient light and 10  V/μm.