An optical fiber cable for bi-directional communication of optical signals is disclosed. The optical fiber cable has a primary multimode optical fiber with an alpha value of and is concatenated to a compensating fiber with an alpha value , wherein 1.2()0.1. The optical fiber cable has a reach between 50 m and 800 m. Modules that employ a plurality of concatenated primary and compensating optical fibers are also disclosed. A bi-directional optical fiber communications system that operates at two different wavelengths is also disclosed.

Disclosed is a mode scrambler. The mode scrambler includes a fastening connection component, a first translation plate and a second translation plate. The fastening connection component is provided with an L-shaped groove for placing an optical fiber. The first translation plate and the second translation plate are both connected to the fastening connection component, the first translation plate is configured to reciprocate relatively to the fastening connection component along a radial direction of the optical fiber, and the second translation plate is configured to reciprocate relatively to the fastening connection component in a vertical direction. The second translation plate is abutted against a top of the optical fiber and is in close contact with a part of the sinusoidal surface of the first translation plate. The optical fiber is enclosed among the fastening connection component, the first translation plate and the second translation plate.

A light source unit generates an optical signal out of a bend-insensitive (BI) optical fiber that is compliant with a desired encircled flux (EF). The unit includes a light source to generate an optical light signal and a conventional multimode optical fiber coupled to receive the optical light signal from the light source at a first end. A modal conditioner is arranged to condition the optical light signal propagating along different modes of the conventional multimode fiber. A first bend-insensitive (BI) multimode optical fiber has an input end, the input end of the first BI multimode optical fiber being coupled at a second end of the conventional multimode optical fiber to receive the conditioned optical light signal from the conventional multimode fiber. The output from the first BI multimode optical fiber outputs an optical signal having the desired EF.

There is provided a modal distribution conditioner comprising the combination of a mandrel-wrapped optical fiber and an adjustable and fixable loop of optical fiber. It is noted that light entering the modal distribution conditioner is to be generally overfilled compared with the target encircled flux function (as defined by the Standard). The mandrel wrapping introduces macrobends to the optical fiber, inducing modal pre-filtering that roughly transforms the initially overfilled modal distribution to be close to compliance with the appropriate Standard. However, the modal distribution of light having traversed the fixed mandrel typically remains somewhat overfilled. The adjustable loop provides for the fine-tuning of the modal distribution, in conformity with the Standard. Once the requirements defined by the Standard are met, the adjustable loop may be secured in place such that modal distribution becomes fixed and remain stable.

An integrated optical coupler device comprising, on a substrate surface: an integrated optical coupling grating extending in lateral directions parallel to the substrate surface and which, by diffraction at its grating structures, either converts electromagnetic waves, guided parallel to the substrate surface, of at least two waveguide modes of integrated optical waveguides into fiber modes propagating perpendicularly to the substrate surface, or converts electromagnetic waves, propagating perpendicularly to the substrate surface, of a fiber mode into electromagnetic waves, propagating parallel to the substrate surface, of at least two waveguide modes, and a first conductor pair, connected to the coupling grating and formed by a first and a second integrated optical waveguide, through which, in mutually opposite first and second directions parallel to the substrate surface, electromagnetic waves of at least two waveguide modes can be conducted to the coupling grating or can be conducted away from the coupling grating.

Embodiments of present invention provide a digital dispersion compensation module. The digital dispersion compensation module includes a multi-port optical circulator and a plurality of dispersion compensation units connected to the multi-port optical circulator, wherein at least one of the plurality of dispersion compensation units includes a first and a second reflectively terminated element and an optical switch being capable of selectively connecting to one of the first and second reflectively terminated elements, and wherein the at least one of the plurality of dispersion compensation units is adapted to provide a substantially zero dispersion to an optical signal, coming from the multi-port optical circulator, when the optical switch connects to the first reflectively terminated element and is adapted to provide a non-zero dispersion to the optical signal when the optical switch connects to the second reflectively terminated element.

An optical fiber (OF) spatial mode filter element includes a structure having an internal cylindrical volume and is adapted to connect an exit end of a first OF with an entrance end of a second OF. An index of refraction of the structure is greater than an index of refraction of a material within the internal cylindrical volume, and when disposed between the exit end of the first OF with the entrance end of the second OF a gap width of the hollow volume between the exit end of the first OF and the entrance end of the second OF defines an effective numerical aperture of the entrance end of the second OF.

The present embodiment relates to an MCF in which the strength of mode coupling or power coupling between adjacent cores included in one coupled-core group is set to an appropriate level to reduce a DGD. The MCF includes at least one coupled-core group. A core interval between adjacent cores included in the coupled-core group is set such that a mode coupling coefficient between the adjacent cores at a wavelength of 1550 nm satisfies 2.610.sup.0 [m.sup.1] to 1.610.sup.2 [m.sup.1] or a power coupling coefficient between the adjacent cores at the wavelength of 1550 nm satisfies 1.310.sup.3 [m.sup.1] to 8.110.sup.0 [m.sup.1].

A patch cord for transmitting between a single mode fiber (SMF) and a multi-mode fiber (MMFs) has a MMF, SMF, and a photonic crystal fiber (PCF) with a hollow core placed between the SMF and MMF. A mode field diameter (MFD) of the PCF hollow core section is in the range of 16 to 19 microns, the length of the PCF is between 1 cm to 10 cm, the MMF has 502 microns core diameter, the SMF has a 6-9 microns core diameter, and the coupling between the PCF mode to the MMF fundamental mode is maximized.

A fiber span comprising: a first optical fiber and a second optical fiber coupled to the first optical fiber, both fibers comprising the an inner core region with maximum refractive index delta, .sub.00.1% and an outer radius R.sub.1>4.5 m, an outer core region with an outer radius R.sub.2 and a minimum refractive index delta .sub.1 and alpha value 5, wherein .sub.1<.sub.0, 5.5 mR.sub.2R.sub.112 m; a cladding including a low index ring surrounding the core and a minimum refractive index delta .sub.R,MIN<.sub.1; and an outer cladding having .sub.Outer-Clad>.sub.R,MIN; the first fiber introducing differential mode delay DMD.sub.1 for wavelengths between 1525 and 1570 nm such that |DMD.sub.1|100 ps/km, and a first differential mode delay slope DMDS.sub.1; the second fiber introducing differential mode delay DMD.sub.2 for wavelengths between 1525 and 1570 nm such that |DMD.sub.2|100 ps/km, and a second differential mode delay slope DMDS.sub.2 that has an opposite sign from the first dispersion slope DMDS.sub.1; wherein total differential mode delay provided by the first fiber in conjunction with the second fiber is DMD.sub.tot=DMD.sub.1+DMD.sub.2, and 1.0 ps/km<DMD.sub.tot<1.0 for all wavelengths between 1525 nm and 1570 nm.