Abstract: Described is a general strategy of bend-compensated, single-mode LMA fibers extended into a regime with higher total index contrast and where a larger gradient is used to cancel the perturbation of a tighter anticipated bend.

Abstract: A hollow core fiber having polarization dependent loss is provided. The hollow core fiber embedded in a cellular cladding having a plurality of cells arranged in a nominally regular cellular lattice. A pre-determined number of cells at pre-determined locations within a cellular cladding are substituted by leakage cells that differ in at least one property including a physical or a chemical property, or both. The leakage cells collectively provide a leakage path that may preferably be made polarization sensitive, such that a core mode with a particular polarization state is selectively coupled to the cladding, thereby inducing polarization dependent loss. The leakage cells may be dispersed along a symmetry axis in a radial distance longer than one or more lattice spacing away from the core. The polarization dependent loss may be controlled further by asymmetric core shapes and/or by introducing additional surface features along the core-cladding interface.

Abstract: An optical fiber includes a core region having a longitudinal axis. A cladding region surrounds the core region. The core region and cladding region are configured to support and guide the propagation of signal light in a fundamental transverse mode in the core region in the directions of the axis. The fiber has a bend-induced gradient of its equivalent index of refraction indicative of a loss in guidance of the mode. At least a portion of cladding region has a graded index of refraction opposite the bend-induced gradient. The cladding region is configured to have a substantially flat equivalent index in response to a bend of the optical fiber.

Abstract: Embodiments of the present invention relate to a fiber design that achieves high nonlinearity, an effective index providing phase matching for an illustrative wavelength conversion process, and a low sensitivity to perturbations in fiber scaling. In one embodiment, a fiber comprises an inner core having an inner core radius and an inner core index, an outer core having an outer core radius and an outer core index, the outer core index being lower than the inner core index, an inner cladding, having an inner cladding radius and an inner cladding index, the inner cladding index being less than the outer core index, and an effective index of the fiber, the effective index being greater than the inner cladding index and less than the outer core index, wherein the fiber has a low perturbation sensitivity factor of dispersion to scaling less than about 20 ps/nm/km along the length of the fiber.

Abstract: A hollow core fiber has a cladding comprising a matrix of cells, wherein each cell comprises a hole and a wall surrounding the hole. The fiber further has a hollow core region comprising a core gap in the matrix of cells, wherein the core gap spans a plurality of cells and has a boundary defined by the interface of the core gap. The matrix of cells comprises 8 plurality of lattice cells, and a plurality of defect cells characterised by at least one difference in at least one property from that of the lattice cells. The cells at the core region boundary include lattice cells and defect cells that are arranged in a pattern that define two orthogonal axes of reflection symmetry, so as to produce birefringence in a light propagating through the hollow core fiber.

Abstract: A few-moded fiber device has several discrete sections of few-moded fibers that are separated by mode converters, with each mode converter accomplishing mode conversion between one or more pairs of modes. The mode conversions can be accomplished using a sequence, such as a periodic or cyclic sequence that would cause (1) a signal wave launched with any mode to assume every other mode for one or more times; (2) the number of times the signal remains in any modal state is substantially the same; and (3) the net signal gain or loss or group delay of the input signal is substantially the same regardless of the state of input mode. A laser few-mode amplifier is provided. An optical transmission system is also provided.

Abstract: An optical fiber coupler connects transmission multicore optical fiber (TMCF) with an amplifier multicore optical fiber (AMCF) and a plurality of optical pump fibers. The coupler includes a plurality of signal cores extending between a multicore input endface and a coupler output endface, and a plurality of pump cores extending between a pump input and the coupler output endface. The multicore input endface is connectable to the TMCF, and the pump input is connectable to the optical pump fibers. Each pump core is paired with a corresponding signal core to form a core pair that is adiabatically tapered such that signal light carried by the signal core is combined with pump light carried by the pump core. The coupler output endface is connectable to the AMCF such that the combined light output of each core pair is provided as an input to a respective AMCF core.

Abstract: An optical fiber includes a core region having a longitudinal axis. A cladding region surrounds the core region. The core region and cladding region are configured to support and guide the propagation of signal light in a fundamental transverse mode in the core region in the directions of the axis. The fiber has a bend-induced gradient of its equivalent index of refraction indicative of a loss in guidance of the mode. At least a portion of cladding region has a graded index of refraction opposite the bend-induced gradient. The cladding region is configured to have a substantially flat equivalent index in response to a bend of the optical fiber.

Abstract: A hollow core fiber having polarization dependent loss is provided. The hollow core fiber embedded in a cellular cladding having a plurality of cells arranged in a nominally regular cellular lattice. A pre-determined number of cells at pre-determined locations within a cellular cladding are substituted by leakage cells that differ in at least one property including a physical or a chemical property, or both. The leakage cells collectively provide a leakage path that may preferably be made polarization sensitive, such that a core mode with a particular polarization state is selectively coupled to the cladding, thereby inducing polarization dependent loss. The leakage cells may be dispersed along a symmetry axis in a radial distance longer than one or more lattice spacing away from the core. The polarization dependent loss may be controlled further by asymmetric core shapes and/or by introducing additional surface features along the core-cladding interface.

Abstract: In an optical fiber, a plurality of individual cores extend through a common cladding. Each individual core supports at least one local transverse spatial mode. The individual cores and surrounding cladding are structured to support propagation of plurality of desired signal-carrying modes, while suppressing undesired modes, thereby supporting the propagation of one or more spatially multiplexed signals. The core-to-core spacing of the fiber is configured to maintain an acceptably low level of mode-coupling between cores.

Abstract: A multicore fiber comprises a plurality of cores extending along the length of a fiber body. Each of the cores is surrounded by a cladding. The plurality of cores and surrounding cladding provide respective index variations, so as to form a respective plurality of waveguides for conducting parallel data transmissions from a first end of the fiber to a second end. The plurality of cores has a cross-sectional geometry in which the plurality of cores is configured in a polygonal array, in which at least some of the cores are positioned at the vertices of the array. The polygonal array is configured such that neighboring cores in the array are separated from each other by a distance that is sufficient to prevent crosstalk therebetween.

Abstract: An optical data link includes first and second pluralities of transmission devices, at least one of which is configured as an array. A multichannel transmission link has a first end connected to the first plurality of transmission devices and a second end connected to the second plurality of transmission devices so as to form a plurality of parallel transmission channels therebetween. The multichannel transmission link includes a multicore fiber with a plurality of individual cores having a configuration matching the array configuration of the at least one plurality of transmission devices. The multicore fiber has an endface connected directly to the at least one plurality of transmission devices, with the individual cores of the multicore fiber aligned with respective devices in the at least one plurality of transmission devices. Further described are access networks and core networks incorporating a transmission link comprising at least one span of a multicore fiber.

Abstract: Embodiments of the present invention relate to a fiber design that achieves high nonlinearity, an effective index providing phase matching for an illustrative wavelength conversion process, and a low sensitivity to perturbations in fiber scaling. In one embodiment, a fiber comprises an inner core having an inner core radius and an inner core index, an outer core having an outer core radius and an outer core index, the outer core index being lower than the inner core index, an inner cladding, having an inner cladding radius and an inner cladding index, the inner cladding index being less than the outer core index, and an effective index of the fiber, the effective index being greater than the inner cladding index and less than the outer core index, wherein the fiber has a low perturbation sensitivity factor of dispersion to scaling less than about 20 ps/nm/km along the length of the fiber.

Abstract: Techniques for analyzing output modal content of optical fibers that support more than one spatial mode are disclosed. These techniques are based on spatially resolving interference between co-propagating modes and constructing a spatial beat pattern between the co-propagating modes. By doing so, these techniques provide information about the modes that propagate along the optical fiber.

Abstract: An optical transmission and amplification system includes a multichannel transmission span with a length of a multicore transmission fiber having a plurality of individual transmission cores. A first tapered multicore coupler provides connectivity between the plurality of transmission cores of the multicore fiber and a respective plurality of individual transmission leads. A fiber amplifier is provided having a plurality of individual cores including at least one pump core and a plurality of amplifier core. A second tapered multicore coupler provides connectivity between the amplifier cores of the fiber amplifier and a respective plurality of amplifier leads, and between the at least one pump core and a respective pump lead.

Abstract: 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 nout less than the index n1 of the core, (ii) an inner cladding having an index n2<nout, (iii) a pedestal having an index n4?nout, (iv) an inner trench disposed between the inner cladding and the pedestal, the inner trench having an index n3<<n4, and (iv) an outer trench disposed between the pedestal and the outer cladding, the outer trench having an index n5<n4 and relatively close to nout. 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.

Abstract: An optical fiber coupler connects transmission multicore optical fiber (TMCF) with an amplifier multicore optical fiber (AMCF) and a plurality of optical pump fibers. The coupler includes a plurality of signal cores extending between a multicore input endface and a coupler output endface, and a plurality of pump cores extending between a pump input and the coupler output endface. The multicore input endface is connectable to the TMCF, and the pump input is connectable to the optical pump fibers. Each pump core is paired with a corresponding signal core to form a core pair that is adiabatically tapered such that signal light carried by the signal core is combined with pump light carried by the pump core. The coupler output endface is connectable to the AMCF such that the combined light output of each core pair is provided as an input to a respective AMCF core.

Abstract: A LMA, single-mode optical fiber comprises a core region, an inner cladding region surrounding the core region, and an outer cladding region surrounding the inner cladding region. The inner cladding region is configured to provide bend compensation. In one embodiment the index profile of the inner cladding region is graded with a slope of ?ncore/Rb, where ncore is the refractive index of the core region, Rb is the bend radius, and ?=0.6-1.2. In addition, the inner cladding is annular and the ratio of its outer radius to its inner radius is greater than 2. In a preferred embodiment this ratio is greater than 3. The overall index profile may be symmetric or asymmetric.

Abstract: An optical fiber has two or more core regions disposed within a common cladding region. Each of the core regions is configured to guide a respective light transmission comprising at least one optical mode along the length of the fiber. The cores are arranged within the common cladding region according to a core configuration that substantially prevents crosstalk between modes of neighboring cores in the fiber, in a deployment of the fiber in which cross-coupling between neighboring cores is affected by perturbations arising in the deployed fiber.

Abstract: Devices and techniques are described for connecting each of plurality of terminals to respective individual cores of a multicore fiber. Each of the plurality of terminals is provided with a respective length of a single-core fiber. The single-core fibers are configured to maintain modal properties that arc substantially the same, within a tolerance range, at the front and rear ends, as the single-core fiber is tapered. The single-core fibers are assembled together. The front end of the assembly is tapered to form a front cross-section in which the single-core fiber cores are arranged in a configuration matching that of the cores of the multicore fiber.