OM3 (multimode optical fiber with a core size of 50 micrometers) is commonly used in data center and enterprise environments to support high-speed networking applications, including 40 Gigabit Ethernet (40GbE). The maximum reach for OM3 fiber at 40G is typically specified by industry standards and can depend on the optical transceivers used.

For 40GbE over OM3 fiber, the common reach specifications are:

1. SR4 (Short Range 4):

• Reach: Up to 100 meters (328 feet)

• Module Type: QSFP+ (Quad Small Form-Factor Pluggable) SR4 transceivers are commonly used.

It's important to note that the reach specifications mentioned above are general guidelines, and actual performance may be influenced by factors such as connector quality, the quality of the fiber optic cable, and environmental conditions.

If longer reach is required, you might consider using different fiber types, such as OM4 or single-mode fibers. However, it's crucial to ensure that the optical transceivers and other networking equipment are compatible with the chosen fiber type.

Always refer to the specifications provided by the equipment manufacturers and industry standards to ensure accurate information for your specific deployment. Additionally, advancements in technology may lead to new transceivers and standards, so it's advisable to check the latest documentation and standards for the most up-to-date information.