Advanced Pixel Engineering for High-Resolution Spatial Light Modulators Based on Liquid Crystal on Silicon Technology

Spatial light modulators (SLMs) based on liquid crystal on silicon (LCOS) technology have been widely used in various advanced optical systems, including information displays, data communication, quantum optics, precision manufacturing, etc. LCOS technology is rapidly evolving toward higher resolution with smaller pixel pitches. This promises the development of highly compact optical systems with enhanced capabilities. However, high-resolution LCOS devices often suffer from poor optical efficiency, a mechanism that cannot be explained by conventional theory based on the filling factor of the pixel array. In this work, we conducted a thorough investigation into the loss mechanism of high-resolution LCOS devices. It has been identified that surface plasmon polaritons (SPPs) and subwavelength gap cavity modes (CMs) are the primary sources of optical loss. Based on these findings, a simple modification of the pixel array structure was developed and experimentally validated. As a result, the reflectivity of the modified pixel array was improved to >90% within the target wavelength range. The thickness of our reflectivity enhancement layer was more than 95% smaller than that of the conventional dielectric mirror used to enhance reflectivity within the same wavelength range. These results provide fundamental insights for the future development of high-resolution LCOS devices.