Good document by Tony Irujo (thank you) on OM4
As the demand for bandwidth in enterprise applications such as data centers continues to boom, new transmission media must be developed continually to meet end user requirements. The latest in optical transmis- sion media for the enterprise is called OM4 fiber.
OM4 fiber is a 50 micron (μm) laser-optimized multimode fiber with extended bandwidth. It is designed to enhance the sys- tem cost benefits enabled by 850 nm Vertical Cavity Surface Emitting Lasers (VCSELs) for existing 1 and 10 Gb/s applications as well as future 40 and 100 Gb/s systems.
Get the document here