Types of optical fibers
Lód is a transmission medium in which the propagation of light as a carrier is used for transmission information. The advantages are transmission with a larger bandwidth compared to other transmission media and its range. A modulated light wave is used for data transmission, the source of which may be a semiconductor laser or a light-emitting diode. Optical fibers do not emit an external electromagnetic field, so it is almost impossible to eavesdrop on the transmission. They can be categorized by mode structure, refractive index distribution and geometry. Advantages of fiber optic cabling: small dimensions and weight, huge information capacity of a single fiber, low fiber losses, long-distance transmission of information, resistance to interference, difficult eavesdropping of transmitted data, reliability of correctly made fiber optic installations.
Fashion structure
Due to the mode structure, we distinguish single-mode and multi-mode fibers. They differ in the thickness of the glass core (other layers have the same thickness), which affects the way information is transmitted.
Single-mode fiber
The diameter of the core is from 8 to 10 micrometers (standard 9 micrometers) and a step change in the refractive index. The most common jacket diameter is the standard diameter of 125µm. The signal is slightly distorted (no intermode dispersion). The light wave propagates almost parallel to the fiber axis and reaches the end of the fiber in one basic mode. This type of optical fiber is used in long-distance communication because the signal can be transmitted over a distance of up to 100-120 km without the need for its regeneration. It depends on the optical equipment used. Effective data transfer is ensured by using multiple protocols simultaneously.
- G.652D (SM2) Single-mode optical fibers with unshifted dispersion
Application: The most commonly installed fiber type, optimized for 1310 nm transmission, can also be used for 1550 nm transmission. The bending radius of the fibers is 30mm as standard. - G.657A1 (S7A1) Single-mode fibers with a reduced bending radius of 15 mm
Application: Fibers with a minimum bending radius of 15 mm are compatible with standard G.652D single-mode fibers - G.657A2 (S7A2) Single-mode fibers with a reduced bending radius of 10 mm
Application: fibers with a minimum bending radius of 10 mm, compatible with standard G.652D single-mode fibers - G.657B3 (S7B3) Single-mode fibers with a reduced bending radius of 7.5 mm
Application: fibers with a minimum bending radius of 7.5 mm due to much smaller diameters of the modal field, no compatibility with standard single-mode G.652D fibers
Multimode fiber
The diameter of the core is usually 50 or 62.5 micrometers. The most common jacket diameter is the standard diameter of 125µm. A light wave of the same wavelength can propagate in many ways, called modes. Their speed along the waveguide may be different, and this distorts the pulse, which leads to a limitation of the transmission speed or distance. The signal can be transmitted up to 2 km. It depends on the optical equipment used.
- OM1 62.5/125OM1 multimode optical fibers
Application: They are mainly used for transmission over shorter distances, eg within one building. Wavelengths of 850 nm and 1300 nm are used for transmission. - OM2 50/125 Flex OM2 multimode optical fibers
Application: Due to dispersion, they are mainly used for transmission over shorter distances, eg within one building. Wavelengths of 850 nm and 1300 nm are used for transmission. - OM4 50/125 Flex OM4 multimode optical fibers
Application: They have been designed for use with VCSEL lasers with a wavelength of 850nm, which are used in multimode SFP modules.
