Abstract: A double-clad (DC) multicore (MC) Erbium-doped fiber amplifier (EDFA) for dense-wavelength-division multiplexing (DWDM) is disclosed. The DC-MC-EDFA comprises a length of DC-MC Erbium-doped fiber (EDF) that is core-matched spliced to a MC tapered signal-pump fiber combiner (TFC). For some embodiments, the optical signals are coupled into the DC-MC-EDF by the MC-TFC, and the pump energy is also coupled into the DC-MC-EDF by the MC-TFC. For some embodiments, the optical signals are also transmitted out of the DC-MC-EDF through the MC-TFC.

Abstract: A multicore optical fiber includes a plurality of core regions disposed within a common cladding region. Each of the plurality of core regions is configured, in combination with the common cladding region, to propagate light along a longitudinal axis of the fiber. At least two core regions are configured to inhibit resonant coupling of propagated light therebetween within a selected region of operation. At least one segment of the fiber includes a twist that is configured such that when the twisted segment is subjected to a bend having a selected radius, the twist creates a controlled change in the amount of crosstalk between the at least two core regions, compared with the amount of crosstalk between the at least two core regions when a bend having the selected radius is introduced into a non-twisted segment of the fiber.

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 double-clad (DC) multicore (MC) Erbium-doped fiber amplifier (EDFA) for dense-wavelength-division multiplexing (DWDM) is disclosed. The DC-MC-EDFA comprises a length of DC-MC Erbium-doped fiber (EDF) that is core-matched spliced to a MC tapered signal-pump fiber combiner (TFC). For some embodiments, the optical signals are coupled into the DC-MC-EDF by the MC-TFC, and the pump energy is also coupled into the DC-MC-EDF by the MC-TFC. For some embodiments, the optical signals are also transmitted out of the DC-MC-EDF through the MC-TFC.

Abstract: A high-powered double cladding (DC) pumped Ytterbium-free L-band Erbium doped fiber amplifier (EDFA) for dense-wavelength-division multiplexing (DWDM) is disclosed. The DC pumped Ytterbium-free L-band EDFA comprises a length of DC Erbium-doped fiber (EDF) that has a low-index, large-diameter core. For some embodiments, the DC-EDF also comprises a trench that is located radially exterior to the cladding, thereby increasing cladding absorption while still effectively maintaining single-mode behavior.

Abstract: A passive, coexisting 10 Gb/s passive optical network (XGPON) and Gb/s passive optical network (GPON) is created by using a pair of counter-propagating laser pump sources at a network-based optical line terminal, in combination with a feeder fiber, to create distributed Raman amplification for the upstream signals associated with both GPON and XGPON systems. A passive remote node is located at the opposite end of the feeder fiber, in the vicinity of a group of end-user locations, and includes a cyclic WDM and a pair of power splitters for the GPON and XGPON signals such that the GPON signals are thereafter directed through a first power splitter into optical network units (ONUs) specifically configured for GPON wavelengths and XGPON signals are directed through a second power splitter into ONUs configured for the XGPON wavelengths. The arrangement of the remote node allows for the reach and split ratios of the GPON and XGPON systems to be individually designed for optimum performance.

Abstract: A double-clad (DC) multicore (MC) Erbium-doped fiber amplifier (EDFA) for dense-wavelength-division multiplexing (DWDM) is disclosed. The DC-MC-EDFA comprises a length of DC-MC Erbium-doped fiber (EDF) that is core-matched spliced to a MC tapered signal-pump fiber combiner (TFC). For some embodiments, the optical signals are coupled into the DC-MC-EDF by the MC-TFC, and the pump energy is also coupled into the DC-MC-EDF by the MC-TFC. For some embodiments, the optical signals are also transmitted out of the DC-MC-EDF through the MC-TFC.

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: An optical pedestal fiber is configured to be taperable to form a tapered fiber having a mode field diameter at the tapered end that differs from the mode field diameter at the untapered end in correspondence with the difference between the cladding diameter at the tapered end and the cladding diameter at the untapered end. A plurality of such pedestal fibers can be used to construct a tapered fiber bundle coupler that provides matching of both core pitch and mode field diameter between a plurality of input fibers and individual cores of a multicore fiber. Further, the tapered fiber bundle coupler can be constructed using a plurality of fibers, in which individual fibers are configured to have different effective refractive indices, thereby suppressing crosstalk therebetween.

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: 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 bidirectional optical communications network comprises an optical transmission fiber for carrying a downstream signal at a first wavelength and a multiplicity of upstream signals at a second, different wavelength. The fiber is characterized by distributed Raman gain over at least an extended portion of its length. A first terminal, optically coupled to one end of the fiber, includes a first transmitter for generating the downstream signal, a first receiver for detecting the upstream signals, and at least one pump source for generating pump light that provides Raman amplification to either the downstream signal or the upstream signal or both. A multiplicity of second terminals, optically coupled to another end of the fiber, each includes a second transmitter for generating one of the upstream signals, and a second receiver for detecting a downstream sub-signal.

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.

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: 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: A multicore optical fiber includes a plurality of core regions disposed within a common cladding region. Each of the plurality of core regions is configured, in combination with the common cladding region, to propagate light along a longitudinal axis of the fiber. At least two core regions are configured to inhibit resonant coupling of propagated light therebetween within a selected region of operation. At least one segment of the fiber includes a twist that is configured such that when the twisted segment is subjected to a bend having a selected radius, the twist creates a controlled change in the amount of crosstalk between the at least two core regions, compared with the amount of crosstalk between the at least two core regions when a bend having the selected radius is introduced into a non-twisted segment of the fiber.

Abstract: A bidirectional optical communications network comprises an optical transmission fiber for carrying a downstream signal at a first wavelength and a multiplicity of upstream signals at a second, different wavelength. The fiber is characterized by distributed Raman gain over at least an extended portion of its length. A first terminal, optically coupled to one end of the fiber, includes a first transmitter for generating the downstream signal, a first receiver for detecting the upstream signals, and at least one pump source for generating pump light that provides Raman amplification to either the downstream signal or the upstream signal or both. A multiplicity of second terminals, optically coupled to another end of the fiber, each includes a second transmitter for generating one of the upstream signals, and a second receiver for detecting a downstream sub-signal.