Most existing 1G short-haul interfaces are installed using 62.5-micron core multimode fiber. The fiber is sufficient for 1G transmission over a range of 200 meters. The laser-optimized OM2 fiber has a modal bandwidth of 500MHzKm and can reach 500 meters at a transmission distance of 1Gbps. However, network operators are upgrading their 1G links to 10G, and they think they can
Use short-distance 10G optical modules on OM1 fibers
At 10Gbps, the individual light pulses that make up the transmission travel together 10 times less than at 1Gbps. Therefore, the pulse-spreading effect of modal dispersion becomes a problem proportionally faster. Standard 10G short-distance optical modules can only reliably link about 33 meters over OM1 fiber.
10g optical module
In an ideal situation, upgrading from 1G to 10G only requires installing the new 10G equipment as close as possible to the old 1G equipment, then unplugging the fiber from the 1G interface and inserting it into the new 10G optical module. This migration technique can be problematic even on relatively short links.
upgrade solution
To solve this problem, a new type of 10G interface has been developed, called "LRM". These interfaces are designed for backward compatibility with OM1 fiber. The LRM interface transmits in the 1300nm window and is capable of the same transmission distance over OM1 or OM2 fiber. With OM1 fiber, the new 10G LRM actually has greater coverage than a 1G optical module! On OM2 and OM3 fibers, 10G-LRM optical modules do not exactly match 1G performance, but will definitely expand the number of links that avoid fiber upgrades.
new technology
The key to the new LRM interface is the use of advanced signal processing techniques in the receiver portion of these devices. Specialized signal processing is called Electronic Dispersion Compensation or EDC. EDC is done in electronics rather than optics. The EDC chip sits behind the optical detection system and implements a continuous adaptive filtering technique called continuous time filtering. It should be noted that in some cases, in order to achieve the above maximum distances, the use of mode-adjusted patch cord fibers may be required. The mode-adjusting fiber can precisely control the launch angle and position of the single-mode fiber LRM to the multi-mode fiber.
LRM optical module
A mode-adjusting fiber is a special component that allows precise offset of the SMF centerline from the MMF centerline. If desired, use the MCP only when connecting a 1300nm light source to the MMF. Often, it is not known when MCP fiber is required. If you have to upgrade a lot of links from 1G to 10G, and those links are 150 meters or more in length, it's a good idea to have a few MCP fibers on hand. If the new span fails to link when moving the link from a 1G interface to 10G, you can insert an MCP at the transmit end of one or both ends of the link.
