The present invention provides an optical fiber with improved optical properties such as zero dispersion wavelength by suppressing the volatilization of dopant materials such as germanium dioxide and optimizing the refractive index distribution by adjusting the setting position of the core portion burner for deposition in a larger optical fiber preform. An optical fiber preform includes a core portion with a relatively high refractive index and a clad portion with a relatively low refractive index, wherein a position having a value of 45% of a refractive index difference between a center of the core portion and the clad portion is a boundary rcore (mm) between the core portion and the clad portion; and when a radius position r at which a refractive index difference with the clad portion being a maximum value is rside (mm), r.sub.side/rcore is 0.745 to 1.

An optical signal transmission apparatus and a method are provided. The apparatus may include a set of optical transmitters, each optical transmitter configured for transmission of light signals at one or more wavelengths of light. The apparatus may include an output port configured for transmission of the light signals through a span of optical fiber. The apparatus may use an input port configured to receive other transmissions of light signals through the span of optical fiber. The apparatus may include a set of light detectors, each light detector configured to detect a time delay or phase characteristic associated with the one or more wavelengths of light. The apparatus may include a processor configured to determine a metric based on the detected time delay or phase characteristic.

A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.

A single mode optical fiber including a germania doped silica central core region having outer radius r.sub.1 and refractive index .sub.1, a maximum refractive index .sub.1max, and 0.32%.sub.1max0.45%, and a core alpha profile (Core.sub.). In various embodiments, the optical fiber also contains a cladding region including: (i) a second inner cladding region or ring region surrounding the first inner cladding region; or (ii) an inner cladding region or pedestal region surrounding the germania doped silica central core region. The corresponding resultant optical fibers exhibit a 22 m cable cutoff less than or equal to 1260 nm, a macrobending loss at 1550 nm of 0.75 dB/turn on a 20 mm diameter mandrel, a zero dispersion wavelength, .sub.0, of 1300 nm.sub.01324 nm, and a mode field diameter at 1310 nm of 8.2 micronsMDF.sub.1310 nm9.6 microns.

A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.

The present invention relates to an optical fiber (200) having a core (202) extending along a central axis (206) and a cladding (204) concentrically surrounding the core (202). The core (202) has at least 83-mole percent (mol %) of Silicon dioxide (SiO2) and at most 17-mole percent (mol %) of an up-dopant and, the cladding (204) has at least 99-mole percent (mol %) of Silicon dioxide (SiO2). Further, the optical fiber (200) has (i) an effective area of greater than or equal to 100 ?m.sup.2, (ii) a mode field diameter (MFD) in a range of 11 ?m to 15 ?m, and (iii) a chromatic dispersion of less than or equal to 23.5 picoseconds (ps/(Km.Math.nm) at a wavelength of 1550 nm.

An optical fiber with ultra-low attenuation and bend insensitivity includes a core layer and cladding layers. The cladding layers have an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary outer cladding layer. The core layer has a radius of 3.0-3.9 m, and a relative refractive index difference of 0.04% to 0.12%. The inner cladding layer has a radius of 8-14 m, and a relative refractive index difference of about 0.35% to 0.10%. The trench cladding layer has a radius of about 14-20 m, and a relative refractive index difference of about 0.6% to 0.2%. The auxiliary outer cladding layer has a radius of about 35-50 m, and a relative refractive index difference of about 0.4% to 0.15%. The outer cladding layer is a pure silicon-dioxide glass layer.

A single mode optical fiber including a germania doped silica central core region having outer radius r.sub.1 and refractive index .sub.1, a maximum refractive index .sub.1max, and 0.32%.sub.1max0.45%, and a core alpha profile (Core.sub.). In various embodiments, the optical fiber also contains a cladding region including: (i) a second inner cladding region or ring region surrounding the first inner cladding region; or (ii) an inner cladding region or pedestal region surrounding the germania doped silica central core region. The corresponding resultant optical fibers exhibit a 22 m cable cutoff less than or equal to 1260 nm, a macrobending loss at 1550 nm of 0.75 dB/turn on a 20 mm diameter mandrel, a zero dispersion wavelength, .sub.0, of 1300 nm.sub.01324 nm, and a mode field diameter at 1310 nm of 8.2 micronsMDF.sub.1310nm9.6 microns.

An optical fiber with ultra-low attenuation and bend insensitivity includes a core layer and cladding layers. The cladding layers have an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary outer cladding layer. The core layer has a radius of 3.0-3.9 m, and a relative refractive index difference of 0.04% to 0.12%. The inner cladding layer has a radius of 8-14 m, and a relative refractive index difference of about 0.35% to 0.10%. The trench cladding layer has a radius of about 14-20 m, and a relative refractive index difference of about 0.6% to 0.2%. The auxiliary outer cladding layer has a radius of about 35-50 m, and a relative refractive index difference of about 0.4% to 0.15%. The outer cladding layer is a pure silicon-dioxide glass layer.

The optical fiber according to the present invention includes, in a cross section of the optical fiber, one core region (11) and a cladding region (12) that is arranged on an outer periphery of the core region. The cladding region is a medium that has a lower refractive index than that of the core region and also has a smaller refractive index wavelength dispersion than that of the core region. The optical fiber has a solid core and therefore, allows more reduction in the Rayleigh scattering loss compared to an optical fiber having a hollow core. In addition, since the optical fiber adopts, for the cladding region, a medium that has a smaller refractive index wavelength dispersion than that of the core region, it allows a reduction in the wavelength dispersion of n.sub.eff.