CWDM transmitter

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.

• 1. MZI lattice filter
• 2. CWDM based on cascaded MZI lattice filters
• 3. Four-way WDM
• 4. Eight-way WDM
• 5. Parametric WDM
• 6. Calculating coupler coefficients
• 7. Test your knowledge