Abstract:

The phenomenon of diffraction is a topic usually introduced in a course on wave optics at school level and taught more extensively in advanced optics courses in Physics and Engineering degrees. This theme is a major unit for describing the wave nature of light. Diffraction gratings constitute maybe the most important device used in the study of such phenomenon. Experimental setups based on diffraction gratings can easily be arranged in physics practical labs. However, such laboratory experiences are mostly limited to measurements of diffraction patterns, focusing on their dependence upon the wavelength and direction of propagation of the incident light, along with the periodicity of the grating, thus introducing the grating equation. In fact, it is not that easy to consider the effect of geometrical parameters like the slit width, as well as material specifications. Here we make use of a commercial software enabling to solve Maxwell’s equations numerically, based on the finite element method, which can be used as a complementary platform for training experiences. In this work we show how to implement this software in master classes and laboratories in order to teach the diffraction grating concept and its potential performance improvement by controlling a large number of parameters. Furthermore, students can appropriately visualize the role of such diffraction parameters, and computationally estimate the diffraction efficiency of subwavelength and larger gratings.