Simulating Sine Phase Gratings

Sine phase gratings are common optical elements that achieve light diffraction effects through periodic modulation of light's phase. Simulating such gratings in MATLAB helps us intuitively understand their working principles and optical characteristics. First, it's essential to clarify the fundamental properties of sine phase gratings. These gratings modulate light by applying a sinusoidal phase delay to incident light waves, with their phase distribution typically expressed as a periodic sine function. This structure causes incident light to produce multiple diffraction orders, forming specific diffraction patterns in the far-field. Building such simulations in MATLAB involves several key steps. The first step requires defining spatial parameters including sampling points, sampling interval, and simulation area size using commands like linspace or meshgrid. The second step constructs the grating's phase distribution function, which can be implemented by generating a 2D sinusoidal function matrix through sin(2*pi*x/period) operations. The third step performs light propagation calculations, typically using angular spectrum methods or Fast Fourier Transform (FFT) algorithms with fft2 and ifft2 functions to simulate diffraction processes. For intuitive visualization, we can plot three critical diagrams: the phase distribution of the phase grating, the transmitted field distribution after light passes through the grating, and the far-field diffraction pattern. These plots clearly demonstrate how the grating modulates light waves and produces diffraction effects. By adjusting grating parameters such as period and modulation depth using variable assignments like grating_period and modulation_depth, we can observe corresponding changes in diffraction patterns. This simulation holds significant importance for understanding grating diffraction principles and designing optical systems. In practical applications, sine phase gratings are commonly used in beam splitting, optical information processing, and related fields.