摘要:
A method of manufacturing a glass core preform for optical fibres comprising: providing a porous soot core preform having a central longitudinal hole extending axially therethrough and an a/b ratio of from 0.20 to 0.40; simultaneously dehydrating and doping with fluorine the soot core preform at a temperature of from 1000°C to 1350°C by exposing it to an atmosphere containing a chlorine-containing gas and a fluorine-containing gas, the content of the fluorine- containing gas in the atmosphere being of from 0.01% to 0.50% by volume, and simultaneously consolidating the soot core preform and closing the central longitudinal hole by exposing the soot core preform to an atmosphere substantially devoid of fluorine and of chlorine at a consolidation temperature of from 1500°C to 1650°C, while reducing the pressure down the central hole, thereby forming a glass core preform.
摘要:
Disclosed is an optical fiber having a silica-based core comprising an alkali metal oxide a silica-based core, said core comprising an alkali metal oxide selected from the group consisting of K 2 O, Na 2 O, LiO 2 , Rb 2 O, Cs 2 O and mixtures thereof in an average concentration in said core between about 50 and 1000 ppm by weight, and a silica-based cladding surrounding and directly adjacent the core, said fiber comprising a cable cutoff less than 1400nm chromatic dispersion at 1550nm between about 13 and 19 ps/nm/km and a zero dispersion wavelength less than about 1324nm. By appropriately selecting the concentration of alkali metal oxide dopant in the core and the cladding, a low loss optical fiber may be obtained.
摘要:
Disclosed is an optical fiber having a core of SiO 2 doped with fluorine and an alkali metal oxide dopant. The alkali metal oxide is selected from the group consisting of K, Na, Li, Cs and Rb and is provided in amount of at least 20 ppm wt. %. The fiber has an inner cladding surrounding the core, which also includes fluorine. A relative refractive index of the inner cladding (Δ 2 %), measured relative to pure silica, is preferably between -0.39 % and -0.7 %. The fiber preferably exhibits attenuation at 1550 nm of less than or equal to 0.178 dB/km.
摘要:
Bromine doping of silica glass is demonstrated. Bromine doping can be achieved with SiBr4 as a precursor. Bromine doping can occur during heating, consolidation or sintering of a porous silica glass body. Doping concentrations of bromine increase with increasing pressure of the doping precursor and can be modeled with a power law equation in which doping concentration is proportional to the square root of the pressure of the doping precursor. Bromine is an updopant in silica and the relative refractive index of silica increases approximately linearly with doping concentration. Bromine can be used as a dopant for optical fibers and can be incorporated in the core and/or cladding regions. Core doping concentrations of bromine are sufficient to permit use of undoped silica as an inner cladding material in fibers having a trench in the refractive index profile. Co-doping of silica glass with bromine and chlorine is also demonstrated.
摘要:
A co-doped optical fiber is provided having an attenuation of less than about 0.17 dB/km at a wavelength of 1550 nm. The fiber includes a core region in the fiber having a graded refractive index profile with an alpha of greater than 5. The fiber also includes a first cladding region in the fiber that surrounds the core region. Further, the core region has an effective refractive index of about -0.10% to about +0.05% compared to pure silica. In addition, the core region includes silica that is co-doped with chlorine at about 1.2% or greater by weight and fluorine between about 0.1% and about 1% by weight.
摘要:
The invention relates to a method for producing tetrafluorosilane by decomposing hexafluorosilicic acid with sulfuric acid, which comprises: step 1 of decomposing hexafluorosilicic acid in concentrated sulfuric acid in the first reactor to give SiF 4 and HF and taking out the SiF 4 ; step 2 of transferring part of the concentrated sulfuric acid solution of step 1 containing HF into the second reactor to react the HF with silicon dioxide fed thereinto, thereby producing SiF 4 containing (SiF 3 ) 2 0; and step 3 of bringing the reaction product of step 2 containing (SiF 3 ) 2 O and SiF 4 to the first reactor to react (SiF 3 ) 2 O contained in the reaction product with HF to convert it into SiF 4 and then taking out the SiF4 along with SiF 4 formed in step 1. According to the invention, high-purity SiF 4 can be obtained with (SiF 3 ) 2 Obeing reduced, free from HF generated as a problematic side product in conventional method.
摘要:
A tube (36) is connected to a different tube (27). A rod (22) is put in the different tube (27). Soot (28) is deposited on the outside of the different tube (27). A gas (55) is made to flow through the different tube (27). This structure (32) is then collapsed thereby creating an optical fiber preform.
摘要:
Methods for forming optical fiber preforms are disclosed. According to one embodiment, a method for forming an optical fiber preform includes forming a preform core portion from silica-based glass soot. The silica-based glass soot may include at least one dopant species for altering an index of refraction of the preform core portion. A selective diffusion layer of silica-based glass soot may be formed around the preform core portion to form a soot preform. The selective diffusion layer may have an as-formed density greater than the density of the preform core portion. A diffusing species may be diffused through the selective diffusion layer into the preform core portion. The soot preform may be sintered such that the selective diffusion layer has a barrier density which is greater than the as-formed density and the selective diffusion layer prevents diffusion of the at least one dopant species through the selective diffusion layer.