What Is Parallel Optics?_
Parallel optics use an array of optical transmitters and receivers to send data across multiple fibers in parallel, rather than over a single duplex fiber pair. This approach is standard for 400G and 800G Ethernet and InfiniBand links in data-center leaf-spine fabrics, where each link uses multiple lanes (e.g., 16 fibers for 400G SR8 – 8 transmit, 8 receive). The MPO connector is the physical interface, housing 12, 24, or more fibers in a single ferrule.
Technical Details
Parallel optics rely on vertical-cavity surface-emitting lasers (VCSELs) at 850 nm for multimode fiber, with each lane typically carrying 25G, 50G, or 100G. The MPO connector aligns multiple fibers in a row; polarity and keying (e.g., Type A, B, C) must match per the relevant standard to ensure correct transmit-receive pairing. Link distances are limited to about 100 meters for 400G SR8 on OM4 fiber, as modal dispersion and VCSEL bandwidth constrain reach.
How Leviathan Systems Works with Parallel Optics
In our field deployments, parallel optics are the backbone of the scale-out network (InfiniBand or Ethernet) connecting GPU nodes across racks. We terminate MPO trunks at patch panels and run fan-out cassettes to QSFP/OSFP transceivers on each GPU server’s NIC.
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