Achieving higher spatial resolution in complex amplitude modulation using a pixel shift-based dual-phase modulation method

Abstract

This paper proposes a novel pixel shift-based dual-phase modulation method (PS-DPMM) designed to enhance the spatial resolution of complex amplitude modulations. Conventional techniques, including off-axis computer-generated holograms (CGH), double-phase holograms (DPH), and kinoforms, often encounter issues like low diffraction efficiency, limited spatial resolution, and high speckle noise. Although the dual-phase modulation method (DPMM), which employs two spatial light modulators (SLMs), achieves high diffraction efficiency, its spatial resolution is constrained by the intrinsic pixel size and resolution of the SLM. To overcome this limitation, we propose the PS-DPMM, an extension of the DPMM that introduces a 1/2-pixel shift between two SLMs. Although this sacrifices a portion of the modulation performance, it effectively improves the spatial resolution of complex amplitude modulation by nearly doubling. Through numerical simulations and experimental validation, we demonstrate that the PS-DPMM attains almost twice the spatial resolution of conventional methods while maintaining a relatively high-quality modulation. This approach provides a promising solution for advancing high-spatial-resolution SLM-based complex amplitude modulation with potential applications in holographic displays, fiber-optic systems, and other fields requiring high spatial resolution wavefront control.