117results about "Optical fibre with desired dispersion" patented technology

Disclosed is an optical fiber comprising a center core which forms a passageway for transmitting optical signals and has a refractive index N₁, and a cladding which encloses the center core and has a refractive index N₀. The optical fiber further comprises an upper core, which has a distribution of refractive indices increased starting from a refractive index N₂ (>N₀) at its outer circumference to the refractive index N₁ at its internal circumference, and a minutely depressed refractive index region, which is interposed between said upper core and cladding and has a refractive index N₃. The refractive index N₃ is lower than the refractive index N₀.

Disclosed is an optical fiber having a core with an alkali metal oxide dopant in an peak amount greater than about 0.002 wt. % and less than about 0.1 wt. %. The alkali metal oxide concentration varies with a radius of the optical fiber. By appropriately selecting the concentration of alkali metal oxide dopant in the core and the cladding, a low loss optical fiber may be obtained. Also disclosed are several methods of making the optical fiber including the steps of forming an alkali metal oxide-doped rod, and adding additional glass to form a draw perform. Preferably, the draw preform has a final outer dimension (d2), wherein an outer dimension (d1) of the rod is less than or equal to 0.06 times the final outer dimension (d2). In a preferred embodiment, the alkali metal oxide-doped rod is inserted into the centerline hole of a preform to form an assembly.

Disclosed is an improved optical fiber that employs a novel coating system. When combined with a bend-insensitive glass fiber, the novel coating system according to the present invention yields an optical fiber having exceptionally low losses.

The coating system features (i) a softer primary coating with excellent low-temperature characteristics to protect against microbending in any environment and in the toughest physical situations and, optionally, (ii) a colored secondary coating possessing enhanced color strength and vividness.

The improved coating system provides optical fibers that are useful in buffer tubes and cables having relatively high filling coefficients and fiber counts.

Disclosed is an improved optical fiber that employs a novel coating system. When combined with a bend-insensitive glass fiber, the novel coating system according to the present invention yields an optical fiber having exceptionally low losses.

The coating system features (i) a softer primary coating with excellent low-temperature characteristics to protect against microbending in any environment and in the toughest physical situations and, optionally, (ii) a colored secondary coating possessing enhanced color strength and vividness.

The improved coating system provides optical fibers that are useful in all-dielectric self-supporting (ADSS) cables.

The present invention relates to an optical fiber having a structure suitable for long-distance optical communications, and an optical transmission line including the same. The optical fiber in accordance with the present invention comprises a core region extending along a predetermined axis, and a cladding region disposed so as to surround the outer periphery of the core region; and, as characteristics at a wavelength of 1.55 mum, an effective area of at least 110 mum<2>, a dispersion of 18 to 23 ps/nm/km, and a dispersion slope of 0.058 to 0.066 ps/nm<2>/km.

There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion β₄ of fourth derivative β₄ of propagation constant β with respect to angular frequency ω at a mean zero dispersion wavelength λ₀ in an overall length is not more than 5×10⁻⁵⁶ s⁴/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than ±0.6 nm.

In an optical fiber including a core region and cladding regions of not less than three layers which surround the core region in order, at least one of the cladding regions has lower mean refractive index than both adjacent regions, and at least one cladding region is provided with a plurality of sub medium regions each having a refractive index lower than a main medium constituting this cladding region.

An optical transmission line according to the present invention is an optical transmission line which is able to control both the waveform distortion due to the non-linearity phenomenon and the waveform distortion due to dispersion. The optical transmission line is formed by connecting, in series, the first optical fiber (8), of which the dispersion value in the set wavelength band within the 1.5 mum wavelength band is 6 to 14 ps/nm/km, and the second optical fiber (9), of which the dispersion value in said set wavelength band is -14 to -6 ps/nm/km. The dispersion slopes of the first optical fiber (8) and the second optical fiber (9) are of mutually opposite symbols. Light transmitted from an optical transmitter (11) enters the first optical fiber (8) and light which has been transmitted through the first optical fiber (8) enters the second optical fiber (9). The absolute value of the dispersion in the 1.5 mum wavelength band of each of the optical fibers (8) and (9) is set to be 6 ps/nm/km or more so as to control the four light wave mixture and said absolute value is set to be 14 ps/nm/km or less so as to control a local dispersion, in order to set at approximately zero, for the entire optical transmission line, both the dispersion value and the dispersion slope in said set wavelength band.

A chromatic dispersion-compensating fiber adapted to compensate the chromatic dispersion of a step index monomode fiber in band S presents chromatic dispersion of less than -40 ps/(nm.km) around 1475 nm, chromatic dispersion slope of less than -0.16 ps/(nm2.km), and an effective area greater than or equal to 14 mum2 around said wavelength value. The fiber is monomode at 1475 nm. The fiber can present a rectangle profile with a buried trench and a ring. It serves to compensate chromatic dispersion and chromatic dispersion slope for transmission systems in band S using a step index monomode fiber as the line fiber.

A dispersion compensating fiber, which has a negative dispersion slope with a large absolute value while maintaining the absolute value of the chromatic dispersion, and which has sufficient dispersion slope compensation properties even for the non-zero dispersion shifted optical fiber requiring a large RDS for dispersion compensation. In this dispersion compensating fiber, the radius of a ring core region is set in a range from 6.7 μm to 10.7 μm, the radius ratio of a depressed core region relative to a central core region is set in a range from 2.0 to 3.0, and the radius ratio of the ring core region relative to the depressed core region is set in a range from 1.3 to 2.0, the relative refractive index difference of the central core region relative to the cladding is set in a range from +1.00% to +1.80%, the relative refractive index difference of the depressed core region relative to the cladding is set in a range from −1.20% to −1.50%, and the relative refractive index difference of the ring core region relative to the cladding is set in a range from +0.20% to +0.50%.