Crafting a 1.5 µm pixel pitch spatial light modulator using Ge 2 Sb 2 Te 5 phase change material [Invited]

For this research, we have developed key technologies for a 1.5 µm pixel pitch spatial light modulator (SLM) using ${\rm{Ge}_{2}}{\rm{Sb}_{2}}{\rm{Te}_{5}}$ (GST) phase change material. To uniformly modulate each pixel, we designed a lateral pixel structure in which a heating current flows through a bottom indium tin oxide layer. To check hologram reconstruction both after multilevel fabrication processes and before implementing full source and driver circuits, we fabricated an $8\,\,{\rm{K}} \times 2\,\,{\rm{K}}$ hologram on the topology by changing the GST film’s phase using laser irradiation. To overcome the limitation of SLM size, we tested a physical tiling structure and found that flatness of tiled SLMs was the most important factor in the realization of holographic displays.