1. CWDM transmitter using cascaded MZI lattice filters

In this application example, you will learn how to design a coarse wavelength-division multiplexing filter (CWDM) based on cascaded Mach-Zehnder interferometer (MZI) lattice filters. First, you will learn how to design a general MZI lattice filter starting from directional couplers and delay lengths. Afterwards, we will use directional couplers with a specific coupling ratio and carefully calculated delay lengths to achieve a 2-way demultiplexer with parametric Free Spectral Range (FSR) and parametric center wavelength. In turn, these 2-way multiplexers can then be combined to achieve 4-way, 8-way or n-way demultiplexers. In the final section, we will learn how to further customize the 2-way multiplexers using optical half-band filters. We also provide some exercises to put the above concepts into practice.