Design and Optimization of non-paraxial Diffractive Beam Splitter

Due to their ability to split a single laser beam into multiple beams in combination with well-defined power ratios, diffractive beam splitters are widely used for applications such as laser material processing and optical metrology. But because of the small feature sizes required for non-paraxial or even high-NA splitting or diffraction angles, the design and optimization of this type of device can be challenging. VirtualLab Fusion provides optical engineers with several tools to assist them in this task.

To illustrate the general workflow, we showcase two examples: In the first example, we employ the Iterative Fourier Transform Algorithm (IFTA) alongside a structure design based on the Thin Element Approximation (TEA) to generate a series of initial designs for a beam splitter, which are then rigorously analyzed and further optimized rigorously with the Fourier Modal Method/Rigorous Coupled Wave Analysis (FMM/RCWA). In order to define a suitable and efficient merit function for that last optimization step, the Programmable Grating Analyzer is applied. The second example covers this part of the process in more detail.