Corning: Parallel Optic Technology

Post originated from this Corning White Paper.

Parallel optics is a fiber optic technology primarily targeted for high-data, short-reach multimode fiber systems that are typically less than 150 meters. Parallel optics differs from traditional duplex fiber optic serial communication in that data is simultaneously transmitted and received over multiple optical fibers.

Duplex multimode fiber serial transmission with 850 nm vertical cavity surface emitting lasers (VCSEL) is now being used for data rates up to 16G. Recent 850 nm VCSEL technology advancements have indicated the possibility to support data rates up to 28G. Duplex multimode fiber serial transmission may become impractical beyond 28G due to VCSEL reliability concerns across required operating temperatures. Parallel optics offers an economical solution that typically utilizes OM3 and OM4 multimode fibers, which are optimized for use with VSCEL array sources. For speeds faster then 28G, parallel optics becomes the most practical, cost-effective solution. Current and future protocols expected to use parallel optics include Ethernet, InfiniBand and Fibre Channel.

Parallel optic transmission technology spatially multiplexes or divides a high-data-rate signal among several fibers that are simultaneously transmitted and received. MTP® connectivity is used throughout the parallel optic link and interfaces into the transceiver module. There are two common transmission protocols that now utilize parallel optics, InfiniBand and Ethernet. InfiniBand has the 4X, 8X and 12X parallel optics transmission variants but primarily utilizes the 4X and 12X solutions. InfiniBand specifies various lane speeds defined as single data rate (SDR), double data rate (DDR) and quad data rate (QDR). See Table 1. The 4X solution is a 4-channel transceiver product that is capable of transmitting four channels and receiving four channels. The 12X solution is a 12-channel product that is capable of transmitting 12 channels and receiving 12 channels. Figures 1 and 2 illustrate the channel configurations for InfiniBand 4X and 12X variants.

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