The catalyst of Chinese fiber industry – photonic crystal fiberadmin
A thin glass fiber can equate to thousands of books of information almost instantaneously transmitted to hundreds of kilometers away. In the modern communications industry, it has already replaced the copper wire, become long-distance signal transmission vectors. Optical fiber since 1966 came, people first goal is to minimize the loss. The late 1970s, the fiber has reached only 4-5% per kilometer energy loss (0.2dB / km), the optical signal can be transmitted tens of kilometers; the development of technology, to the late 1980s, the erbium-doped fiber amplifiers (Erbium Doped Fiber Amplifier , EDFA) market, the optical signal transmission can be enhanced, completely solve the historic problem of fiber loss, to achieve ultra-long haul transmission of information across the ocean. Optical fiber communications industry as a vibrant new force to grow and flourish to play. Thus, with “Father of Fiber Optics” reputation of the Chinese scientist Charles Kao Nobel prize in physics in 2009.
Since 1990, due to the rapid growth of online data communication service, making it the traditional communication system requirements for continuous improvement, greater capacity, higher speed, longer transmission distance of optical fiber communication systems appears. However, in the conventional fiber optic systems, problems such as dispersion, nonlinearity, and next-generation all-optical networks simple logic functions (such as: optical switch) problem, which requires a new fiber-optic technology and devices for support.
From the conventional optical fibers to a photonic crystal fiber
1987, Eli Yablonovitch and other scientists have found that some animals have hairs surface periodically regular arrangement, you can put some color (corresponding to a certain wavelength) of the light totally reflected, absorbed other wavelengths, showing bright colors, as shown in Figure 1 feathers and peacock butterfly wings surface as shown in exhibit bright colors. Eli Yablonovitch the like of such structures named “photonic crystal.” Soon, the fiber structure in the field of transplantation has been applied. In 1992, Phillip Russell et al., “Photonic crystal fiber” (microstructure fiber in a class). Photonic crystal fiber is composed of a group of fine quartz capillary periodically arranged in a hexagonal, as seen in cross-section, like a honeycomb structure. Due to the excellent transmission characteristics of photonic crystal fibers rapidly gaining importance in the world.
Conventional fiber structure (FIG. 2, (a)) it is usually made from two glass material, comprising a core and a cladding having a lower refractive index higher refractive index, the total reflection of light in the form of high core refractive index material spread. Photonic crystal fiber prepared by a single material (eg: quartz glass), hollow core and solid core is divided into two structures. Solid-core photonic crystal fiber structure is usually a two-dimensional array of capillaries in accordance with hexagons, most central capillary is replaced by silica glass rod to form a photonic crystal defect (Figure 2 (b)), the light spread this solid core defect. Works of this fiber and optical fiber close to the traditional, through the core and cladding of different refractive index propagation. This is because the cladding layer contains an air hole, such that the effective refractive index of the cladding is less than the core refractive index, the total reflection light is formed in the core. Hollow-core photonic crystal fiber (Fig. 2 (c)) is the only kind of material silica, but with the traditional fiber and solid-core photonic crystal fiber conduction mechanism is completely different, hollow-core photonic crystal fiber is a photonic bandgap principle, the use photonic bandgap optical transmission in the air. In light of such a photonic crystal fiber is spread by the middle of the pores, so there is no conventional optical fiber transmission window, loss, dispersion and other restrictions.