The example illustrates OptSim Circuit simulation of a photonic integrated circuit (PIC) based on components using the PDAFlow interface and the LioniX foundry (the example assumes that you have a valid PDAFlow license for this foundry). The topology of Figure 1(a) simulates the transfer function response of two different Mach-Zehnder interferometer (MZI) designs, each based on the compound component (CC) shown in Figure 1(b). If you view the properties for either of the two MZI CCs in the top-level topology, you will see that the LioniX foundry is being used.
The MZI design uses various building blocks from the PDAFlow LioniX foundry, including straight and arced waveguides, as well as Y junctions. The upper MZI in Figure 1(a) has an arm-length difference of approximately 202 µm, while the lower MZI has an arm-length difference of approximately 302 µm. Figures 2(a) and 2(b) show the output spectra for the upper and lower MZIs, respectively. Comparison of the two plots reveals that the larger arm-length difference in the lower MZI results in a smaller free-spectral range (FSR).