The Future of Passive Multiplexing and Multiplexing Beyond 10G. In the past, it was easy to change your optical network from 1G to 10G by simply changing the transceiver, but what if you want to do more than 10G? What if you want to go beyond 80km? What are your options and why is there no QSFP28-DWDM-ZR? These are the central questions in this presentation. We will cover the 3 “ingredients” of Multiplexing: The Fiber, the Passive Mux, and the Transceiver, and talk about the limitations and possibilities of multiple times 100G over one fiber pair. We will also cover the following topics: The challenges that arise due to attenuation and chromatic dispersion; Different types of Multiplexers – Cascaded TFF and AWG (including Gaussian Fit and Flat Top); ITU Grids such as DWDM and the new LWDM band (often used for 5G deployment); Modulation & Coherent 100G/200G/400G; How to use QSFP28 DWDM PAM4; and what is coming in 2020 – 400G DWDM QSFP-DD. At the end of this talk, you will understand the future of 100G multiplexing and how it can fit into your network.