Classification of Optical Fiber
There are many types of optical fibers, and there are various classification methods.
From the Material Point of View
According to the materials used in the manufacture of optical fibers, there are silica-based optical fibers, multi-component glass optical fibers, plastic-clad silica-core optical fibers, all-plastic optical fibers, and fluoride optical fibers. Plastic optical fiber is made of highly transparent polystyrene or polymethyl methacrylate (plexiglass). It is characterized by low manufacturing cost, relatively large core diameter, high coupling efficiency with the light source, high optical power coupled into the optical fiber, and convenient use. However, due to the large loss and small bandwidth, this kind of optical fiber is only suitable for short-distance and low-rate communication, such as short-distance computer network links and intra-ship communications. At present, quartz-based optical fibers are commonly used in communications.
According to the Transmission Mode
According to the transmission mode of light in the fiber, it can be divided into: single-mode fiber and multi-mode fiber.
The core diameter of the multimode fiber is 50-62.5um, and the outer diameter of the cladding is 125um. The core diameter of the single-mode fiber is 8.3um and the outer diameter of the cladding is 125um. The working wavelength of the optical fiber has short wavelength 0.85um, long wavelength 1.31um and 1.55um. Fiber loss generally decreases with the lengthening of the wavelength. The loss of 0.85um is 2.5dB/km, the loss of 1.31um is 0.35dB/km, and the loss of 1.55um is 0.20dB/km. This is the lowest loss of fiber, with a wavelength of 1.65 The loss above um tends to increase. Due to the absorption of OH, there are loss peaks in the ranges of 0.90~1.30um and 1.34~1.52um, and these two ranges are not fully utilized. Since the 1980s, single-mode fibers have tended to be used more often, and long-wavelength 1.31um has been used first.