Ofs Fitel, LLC

Fitel USA Corporation

Yi Sun

David W Peckham

Robert L Lingle

John Michael Fini

Lars Gruner-Nielsen

Jinkee Kim

George Edward Oulundsen, Iii

Xinli Jiang

Man Fei Yan

David Kalish

Robert Lingle, Jr

Durgesh Vaidya

Fengqing Wu

Robert Lee Lingle, Jr

George Oulundsen

A few-mode fiber is described, having a graded-index core and a surrounding cladding comprising a ledge between the core and the trench, a down-doped trench abutting the ledge, and an undoped cladding region abutting the trench. The fiber's refractive index profile is configured to support 9 or more LP modes for transmission of a spatially-multiplexed optical signal. Undesired modes have respective effective indices that are close to, or less than, the cladding index so as to result in leakage of the undesired modes into the outer cladding. The index spacing between the desired mode having the lowest effective index and the leaky mode with the highest effective index is sufficiently large so as to substantially prevent coupling therebetween.

Multiple LP-mode fiber designs for mode-division multiplexing

A few-mode fiber is described, having a graded-index core and a surrounding cladding comprising a ledge between the core and the trench, a down-doped trench abutting the ledge, and an undoped cladding region abutting the trench. The fiber's refractive index profile is configured to support 9 LP modes for transmission of a spatially-multiplexed optical signal and has optimized maximum differential group delay (MDGD) through a wide range of wavelengths.

9 LP-mode fiber designs for mode-division multiplexing

Optical fiber designs are depicted with a core having an alpha profile inner portion and a steep vertical step between the core and a cladding with no shoulder, referred to herein as a truncated core. A further aspect of this invention can include a trench between the truncated core and cladding. In this embodiment, the core performs as not only as the primary light guiding structure, but now also functions essentially the same as that of a trench structure. Thus, what was formally a trench can now be much less negative or even positive. Another embodiment of the present invention includes an optical fiber having a truncated core with the addition of a ledge or shoulder between the core and vertical step, followed directly by a cladding.

Optical fibers with truncated cores

The specification describes modified step index and GRaded INdex (GRIN) fibers with low core relative delta (near 0.8%) which have desirable properties for transmission. These lower delta fibers have lower attenuation losses due to reduced Rayleigh scattering, which is desirable to improve performance in multiple mode multiplexing. The fiber designs include optimized raised triangle profiles, and depressed cladding profiles, to support two and four LP modes.

Multiple LP mode fiber designs for mode division multiplexing

Optical fiber refractive index profile designs having an alpha core profile and a negative index trench to control bend loss, are modified by truncating the edge of the alpha core profile and adding a ledge to the truncated core. The result is low bend loss and preservation of low differential mode delay and high bandwidth.

DMD performance in bend optimized multimode fiber

Described is a modular method of making an optical fiber comprising a core and a cladding configured to support and guide a fundamental transverse mode, the cladding including (i) an outer cladding having an index nless than the index nof the core, (ii) an inner cladding having an index n&#x3c;n, (iii) a pedestal having an index n&#x2248;n, (iv) an inner trench disposed between the inner cladding and the pedestal, the inner trench having an index n&#x3c;&#x3c;n, and (iv) an outer trench disposed between the pedestal and the outer cladding, the outer trench having an index n&#x3c;nand relatively close to n. To suppress unwanted HOMs the pedestal is configured to resonantly couple at least one unwanted transverse mode of the core (other than the fundamental mode) to at least one transverse mode of the pedestal.

Modular method of making single mode optical fibers

Optical fiber comprises core and a cladding configured to support and guide a fundamental transverse mode, the cladding including (i) an outer cladding having an index nless than the index nof the core, (ii) an inner cladding having an index n&#x3c;n, (iii) a pedestal having an index n&#x2dc;n, (iv) an inner trench disposed between the inner cladding and the pedestal, the inner trench having an index n&#x3c;&#x3c;n, and (iv) an outer trench disposed between the pedestal and the outer cladding, the outer trench having an index n&#x3c;nand relatively close to n. To suppress unwanted HOMs the pedestal is configured to resonantly couple at least one unwanted transverse mode of the core (other than the fundamental mode) to at least one transverse mode of the pedestal. Also described is a modular method of making the optical fiber of silica glass.

Single mode optical fibers and modular method of making same

Described are multimode optical fibers in which the differential in the mode delay for higher order modes is reduced for bending insensitive MMF. The result is preservation of low differential mode delay and high bandwidth while low bend loss is achieved. The designs are based on choosing a combination of a core profile and a cladding structure with a negative trench positioned at a radius related to the core profile. A feature of the preferred embodiments is a core with a hybrid refractive index profile. The hybrid refractive index profile is essentially a combination of a standard alpha profile and a step profile at the outer edge of the alpha profile.

Equalizing modal delay of high order modes in bend insensitive multimode fiber

An inverse dispersion fiber having a large effective area and a transmission system that incorporates the fiber for providing dispersion and dispersion slope compensation in a transmission fiber. The large-effective-area inverse dispersion optical fiber (IDF) has a negative dispersion and a negative dispersion slope. The effective area, A, of the IDF preferably is greater than approximately 31 micrometers squared (&#x3bc;m) at a transmission wavelength of approximately 1550 nm. The large-effective-area IDF is suitable for use with super-large-effective-area (SLA) transmission fiber for compensating dispersion in the SLA transmission fiber while reducing nonlinear effects between wavelength channels and cabling loss, which is especially advantageous in transoceanic and long-haul terrestrial systems. These nonlinear effects are inversely related to the effective area of the fiber (i.e., nonlinearities&#x2dc;1/A). Thus, an increase in the effective area of the fiber translates into a decrease in nonlinear interactions, which increases bandwidth capabilities and limits signal degradation. Furthermore, the large-effective-area IDF of the present invention has very desirable transmission properties. The present invention also provides a transmission system comprising at least one of the large-effective-area IDF optical fibers of the present invention. Furthermore, Acan be made large without having to increase the ratio, R, of the diameter of the core to the diameter of the trench region.

Large-effective-area inverse dispersion compensating fiber, and a transmission line incorporating the same

A super-large-effective-area (SLA) optical fiber that is suitable for communicating over a wide wavelength range and that, because of its large effective area, suppresses nonlinear effects that typically result from interaction between signal channels. The effective area, A, of the SLA fiber of the present invention preferably is equal to or greater than approximately 80 &#x3bc;mat a wavelength window around 1310 nm. The cutoff wavelength of the SLA fiber of the present invention preferably is less than 1310 nm. Thus, the SLA fiber of the present invention has a very large effective area and a very low cutoff wavelength. In accordance with the present invention, a variety of SLA fibers are provided that all have very large effective areas and desirable transmission properties. The large effective areas of the SLA fibers of the present invention enable nonlinear effects to be suppressed, as well as Stimulated Brillouin Scattering in analog transmission. The large effective areas also enable attenuation to be reduced. The result of suppressing nonlinear effects and reducing attenuation enable signals to be transmitted over long distances and over a broad bandwidth.

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Suwanee, GA, United States of America

Yi Sun