Current status of fiber optic applications

Ordinary single-mode fiber
　　Conventional common single-mode fiber (G.652 fiber) has zero dispersion in the 1310nm wavelength window but high loss (0.35dB/km) and low loss (0.2dB/km) in the 1550nm wavelength window but high dispersion (20ps/nm-km). In order to take advantage of the low loss characteristics of the long 1550nm window of the fiber and the mature optical amplification technology (EDFA), while wanting to have low dispersion, the structure of the fiber can be designed so that the zero-dispersion wavelength is displaced, and the dispersion-shifted fiber is designed, i.e., G.653 fiber.The low loss and low dispersion characteristics of G.653 fiber in the 1550nm wavelength window are well suited for fiber optic soliton The low loss and low dispersion characteristics of G.653 fiber in the 1550nm wavelength window are very suitable for fiber optic soliton communication and have been used in a large number of high-speed fiber optic soliton communication systems, but its dispersion at 1550rim is zero, which will produce serious FWM effects in WDM and is not suitable for WDM systems.
　　High-strength bend-resistant single-mode fiber
　　In the field of optical communications, high-strength bend-resistant single-mode fiber is a competitive fiber, mainly because the focus of fiber optic network construction from the backbone to the metropolitan area network, user access network development, high-strength bend-resistant single-mode fiber-led full-service access network is becoming the main pulling force of the optical cable market, which is representative of the rapidly developing FTTH network, high-strength bend-resistant single-mode fiber characteristics are Fiber can be constructed along the corner of the building, thus reducing the cost of network cabling.
　　Waterless peak fiber
　　Compared with the traditional single-mode fiber, waterless peak fiber has the following advantages: First, in the full range of available wavelengths than conventional fiber increased by about half, the number of wavelengths can be multiplexed greatly increased, can achieve very large capacity transmission; Second, the available wavelength range is greatly expanded, you can use sparse wavelength division multiplexing (CWDM) scheme, the use of wavelength spacing, wavelength accuracy and stability requirements of the lower components, so that components, especially passive devices, the cost of a significant drop; three, 1350 ~ 1450nm wavelength window of the fiber dispersion is only half of the 1550nm wavelength region, easy to achieve high bit rate long distance transmission.
　　Large effective area fiber
　　The main performance limitations of ultra-high speed systems are dispersion and nonlinearity. Usually linear dispersion can be eliminated by dispersion compensation, while the effect of nonlinearity cannot be eliminated by simple linear compensation, and the effective area of the fiber is the main factor determining fiber nonlinearity. In order to accommodate the application of very large capacity long-range dense WDM systems, large effective area fibers have been introduced. In c-band, high-density WDM systems based on 10 Gbit/s consisting of large effective area fibers have been widely used because of their high signal-to-noise ratio, low BER, and long interval of optical amplifiers.
　　Non-zero dispersion fiber for broadband optical transmission
　　Broadband non-zero dispersion flat optical fiber is characterized by G.656 fiber as an example, which should have a dispersion greater than the required non-zero value in the operating wavelength range, a suitable effective area, and a dispersion slope of essentially zero. Therefore, the application of G.656 fiber can both significantly reduce the dispersion compensation cost of the system and further exploit the potentially huge bandwidth of quartz glass fiber. When using G.656 fiber, the channel spacing of 100GHz and 40Gbit/s system can be guaranteed to transmit at least 400km.