(a) Develop a MATLAB (or any other programming language that you prefer) program to simulate the propagation of a square beam (wavelength: 0.5 um, dimension: 1 mm by 1 mm) in free space (propagation distance from 0 to 10 m). Print your code and cross-section images at a few key positions. (a) Develop a MATLAB (or any other programming language that you prefer) program to simulate the propagation of a square beam (wavelength: 0.5 um, dimension: 1 mm by 1 mm) in free space (propagation distance from 0 to 10 m). Print your code and cross-section images at a few key positions