According to transmission frequency: conventional single-mode fiber and dispersion-shifted single-mode fiber.

　　 Conventional: The optical fiber manufacturers frequency the optical fiber transmission to a single wavelength of light, such as 1300μm.

　　 Dispersion shift: The optical fiber manufacturers frequency the optical fiber transmission to two wavelengths of light, such as: 1300μm and 1550μm.

　　2. According to refractive index: abrupt and graded fiber.

　　 Abrupt type: The refractive index from the central core of the fiber to the glass cladding is abrupt. The cost is low and the inter-mode dispersion is high. Suitable for short-distance and low-speed communication, such as industrial control. However, because of the small inter-mode dispersion of the single-mode fiber, the single-mode fiber adopts the abrupt type.

Graded optical fiber: The refractive index from the central core of the optical fiber to the glass cladding is gradually reduced, which can make the high-mode light propagate in a sinusoidal form, which can reduce the inter-mode dispersion, increase the fiber bandwidth, and increase the transmission distance, but the cost is higher. Mode fibers are mostly graded fibers.

　　 3. According to the transmission mode of light in the optical fiber, it can be divided into: single-mode optical fiber and multi-mode optical fiber.

　　Multimode fiber: The center glass core is thick (50 or 62.5μm), which can transmit light of multiple modes. However, the inter-mode dispersion is relatively large, which limits the frequency of the transmission of digital signals, and it becomes more serious with the increase of distance. For example: 600MB/KM fiber has only 300MB bandwidth at 2KM. Therefore, the transmission distance of multimode fiber is relatively short, generally only a few kilometers.

　　Single-mode fiber: The central glass core is thin (the core diameter is generally 9 or 10μm) and can only transmit one mode of light. Therefore, its inter-mode dispersion is very small, which is suitable for long-distance communication, but its chromatic dispersion plays a major role. In this way, single-mode fibers have higher requirements on the spectral width and stability of the light source, that is, the spectral width should be narrow and the stability should be better.