Abstract: A graded refractive index bending-resistant multimode optical fiber includes a core layer and claddings. The core layer has a radius in a range of 22.5-27.5 ?m; refractive indexes being a gradient-graded refractive index distribution with a distribution exponent ? in a range of 1.99-2.06; and a maximum relative refractive index difference (RRID) ?1% max in a range of 0.9%-1.3%. The claddings has an inner cladding surrounding the core layer, an intermediate cladding surrounding the inner cladding and an outer cladding surrounding the inner cladding. The inner cladding has a radius in a range of 25.5-34.5 ?m, and an RRID ?2% in a range of ?0.02%-0.02%. The intermediate cladding is a pure quartz glass layer, and has a radius in a range of 30.5-49.5 ?m, and an RRID ?3% in a range of ?0.01%-0.01%. The outer cladding has a radius in a range of 61.5-63.5 ?m, and an RRID ?4% is in a range of ?0.20%-0.30%.

Abstract: A graded refractive index bending-resistant multimode optical fiber includes a core layer and claddings. The core layer has a radius in a range of 20-50 ?m; refractive indexes being a gradient-graded refractive index distribution with a distribution exponent a in a range of 1.89-1.97; and a maximum relative refractive index difference (RRID) ?1% max in a range of 0.9%-2.72%. The claddings has an inner cladding surrounding the core layer, an intermediate cladding surrounding the inner cladding and an outer cladding surrounding the inner cladding. The inner cladding has a radius in a range of 22-57 ?m, and an RRID ?2% in a range of ?0.02%-0.02%. The intermediate cladding is a pure quartz glass layer, and has a radius in a range of 32-60 ?m, and an RRID ?3% in a range of ?0.01%-0.01%.

Abstract: A bending-resistant large core diameter high numerical aperture multimode fiber includes a core and a cladding surrounding the core. The core has a radius R1 in a range of 28 to 50 microns, a refractive index profile of a parabola shape with ? being in a range of 1.9 to 2.2, and a maximum relative refractive index difference ?1% max being in a range of 1.9% to 2.5%. The cladding includes an inner cladding and/or a trench cladding, and an outer cladding disposed from the inner to the outer in sequence. The radius R2 of the inner cladding is in a range of 28 to 55 microns, and the relative refractive index difference ?2% is ?0.1% to 0.1%. The radius R3 of the trench cladding is in a range of 28 to 60 microns, and the relative refractive index difference ?3% is in a range of ?0.15% to ?0.8%.

Abstract: Techniques for providing data preview before recalling large data files are disclosed. In one aspect, a data file is made accessible while being offline by converting the data file from a native format to a preview format, storing the data file in the preview format in a primary storage that is locally available and moving, after the conversion to the preview format, the data file in the native format to a secondary storage. When a viewing request is received for the data file, the data file in the preview format is displayed to fulfill the viewing request.

Abstract: A method for manufacturing an optical fiber preform, including: a) providing a lining tube as a substrate tube, and doping and depositing by a PCVD or an MCVD process; b) in the reacting gas of silicon tetrachloride and oxygen, introducing a fluorine-containing gas for fluorine doping, introducing germanium tetrachioride for germanium doping, ionizing the reacting gas in the lining tube through microwaves to form plasma, depositing the plasma on the inner wall of the lining tube in the form of glass; c) after the completion of deposition, processing the deposited lining tube into a solid core rod by melting contraction through an electric heating furnace; d) sleeving the solid core rod into a pure quartz glass jacketing tube and manufacturing the two into an optical fiber preform; and e) allowing the effective diameter d of the optical fiber preform to become between 95 and 205 mm.

Abstract: A fiber preform, including: a fiber core rod and an outer cladding layer. The ratio of the diameter of the fiber core rod to the diameter of the core layer thereof is 2.1-2.8. The fiber core rod and a small fluorine-doped quartz glass tube are melted to form a core rod assembly. The ratio of the diameter difference between the core rod assembly and the fiber core rod to the diameter of the core layer is 0.5-2.2. The relative refractive index difference of fluorine-doped quartz glass relative to purified quartz glass ?F is ?0.20% to ?0.35%. The core rod assembly is arranged with a large purified quartz glass tube, or directly deposited with a SiO2 glass cladding layer. A ratio of an effective diameter of the fiber preform to the diameter of the core rod assembly is 2.0-5.6. Methods for manufacturing the preform and a fiber are also provided.