Single-mode fiber (SMF) is having a core of 8 to 10 microns in diameter. Signal is traveling in a single light beam with close to none reflection. Low reflection ratio means lower dispersion. This type of cable can achieve close to max values in distance and bandwidth without repeaters. This type of fiber is commonly used for connecting WAN locations. SMFs specifications make it more expensive, so it is rarely used for short connections. Example of SMF is in Figure 1.
Figure 1. Transmission over single-mode fiber-optic cable.
Multi-Mode Fiber (MMF) is having larger than SMF core of about 50 to 62.5 microns. Signal here is traveling in multiple beams from the LED or laser and it travels in different angles. MMF experience greater attenuation, which make them better option for short distances, than for long ones. MMF is rarely available longer than couple km and is used to connect server to a network backbone. Example of MMF is in Figure 2.
Figure 2. Transmission over multimode fiber-optic cable.
Fiber-Optic Converter is using for interconnection of networks that are using different types of fiber. Depending on the converter, it may also be able to interconnect copper network with the fiber-optic network. Converter also regenerates signal before sending it further. Figure 3 shows FiberbitSingle Mode to Multimode converter FB-SM-MMF
