Phase calculation of diffraction grating based on RCWA

The diffraction grating is an important optical component in the field of optics, used in various optical instruments. Therefore, researching and analyzing the characteristics of gratings holds great significance. RCWA (Rigorous Coupled-Wave Analysis) is an electromagnetic field solving algorithm applied to periodic structures and is an important tool for grating analysis. This paper proposes a diffraction grating phase calculation method based on RCWA. Using a one-dimensional rectangular aluminum metal grating as an example, it calculates the phase of the incident light after encountering the grating and compares the phase calculation results with those obtained from the KAPPA software. Based on the phase calculation, we propose a method for characterizing grating morphology and detecting defects using the principle of phase change after light passes through the grating, offering new possibilities for grating fabrication quality control.