The next speed step in pluggable optics is here and pricing is reaching tolerable levels. While they still use significantly more power than QSFP optics, the actual unit cost of the pluggables is reaching sub $500/pc levels, which makes them viable in many more use cases. I’ve been researching these in order to get myself more familiar with what is available out there. These are my notes for what I’ve found so far. I’ll probably update these a few times as I learn and try more. 400G FR4 The 400G FR4 is a cost-effective pluggable optic that uses duplex LC SMF connectors and operates at a center wavelength of 1310nm. It has a maximum reach of 2km. Features: Duplex LC SMF connectors 1310nm wavelength 2km maximum reach Cost-effective option - available for around $900 list price Use Cases: Short-reach data center interconnects over single mode fiber 1:1 replacement of existing LR4 connections 400G XDR4 The 400G XDR4 is a pluggable optic that uses MPO-12 connectors, single mode fiber, and operates at a center wavelength of 1310nm.

I was recently chatting with a coworker talking through how we use MPO cables and various optics. It made me realize that I have a lot of “in my head” knowledge about fiber cables and optics from working in the networking space over the past 5 years or so, but I haven’t found a good reference point online to point people to and it would probably be better for that information to live written down somewhere rather than it just being in my head. So here it is - everything that is floating around in my head about MPO cables. I’ve done my best to double check what I’m writing here but it should be mostly accurate. What is MPO? MPO (Multi-Fiber Push On) in common terms refers to both the connector and the cable itself.