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.

A method for mitigating modal noise includes applying a time-varying mechanical force to a fiber segment of the multimode optical fiber in at least a first direction orthogonal to a fiber axis of the multimode optical fiber within the fiber segment. A modal-noise mitigator for a multimode optical fiber includes an actuator configured to apply a time-varying mechanical force to a fiber segment of the multimode optical fiber in at least a first direction orthogonal to a fiber axis of the multimode optical fiber within the fiber segment.

According to various aspects of the present disclosure, an apparatus is provided. In an aspect, the apparatus includes an optical transceiver having a first port, a second port and an optical switch coupled to the first port and the second port. The optical switch is switchable between a unidirectional port operation mode and a bidirectional port operation mode. When the optical switch is in the unidirectional port operation mode, the first port is configured to send a first optical signal, and the second port configured to receive a second optical signal. When the optical switch is in the bidirectional port operation mode, the first port configured to send the first optical signal and receive the second optical signal, and the second port configured to receive a third optical signal and not send the first signal. Furthermore, a second bidirectional port operation mode is supported with the second port configured to send the first optical signal and receive the second optical signal, and the first port configured to receive a third optical signal and not send the first signal.

Embodiments are disclosed for a coupling element with embedded modal filtering for a laser and/or a photodiode. An example system includes a laser and an optical coupling element. The laser is configured to emit an optical signal. The optical coupling element is configured to receive the optical signal emitted by the laser. The optical coupling element is also configured to be connected to an optical fiber such that, in operation, the optical signal is transmitted from the laser to the optical fiber via the optical coupling element. Furthermore, the coupling element comprises a tapered section that provides modal filtering of the optical signal.

According to various aspects of the present disclosure, an apparatus is provided. In an aspect, the apparatus includes an optical transceiver having a first port, a second port and an optical switch coupled to the first port and the second port. The optical switch is switchable between a unidirectional port operation mode and a bidirectional port operation mode. When the optical switch is in the unidirectional port operation mode, the first port is configured to send a first optical signal, and the second port configured to receive a second optical signal. When the optical switch is in the bidirectional port operation mode, the first port configured to send the first optical signal and receive the second optical signal, and the second port configured to receive a third optical signal and not send the first signal. Furthermore, a second bidirectional port operation mode is supported with the second port configured to send the first optical signal and receive the second optical signal, and the first port configured to receive a third optical signal and not send the first signal.

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 apparatus includes an all-optical transmission line having, at one wavelength, a pair of relatively orthogonal optical propagating modes whose local group velocities differ along a part of the all-optical transmission line. The all-optical transmission line is formed by a sequence of optically end-connected multi-mode fiber segments. The segments include, at least, 80% of the optical path length of the all-optical transmission line. Each segment is configured such that a differential group delay between the pair varies monotonically there along and changes by, at least, 200 pico-seconds thereon.

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, Δ.sub.0≦0.1% and an outer radius R.sub.1>4.5 μm, an outer core region with an outer radius R.sub.2 and a minimum refractive index delta Δ.sub.1 and alpha value α≧5, wherein Δ.sub.1<Δ.sub.0, 5.5 μm≦R.sub.2−R.sub.1≦12 μm; a cladding including a low index ring surrounding the core and a minimum refractive index delta Δ.sub.R,MIN<Δ.sub.1; and an outer cladding having Δ.sub.Outer-Clad>Δ.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.

An apparatus for laser processing a material including an optical fibre, at least one squeezing mechanism, and a lens. The optical fibre is a multimode optical fibre in which laser radiation propagates in a first optical mode and in a second optical mode. The squeezing mechanism includes at least one periodic surface defined by a pitch. The periodic surface is located adjacent to the optical fibre. The pitch couples the first and second optical modes together. The first optical mode is defined by a first mode order. The second optical mode is defined by a second mode order which is higher than the first mode order. The squeezing mechanism squeezes the periodic surface and optical fibre together with a squeezing force thereby coupling the first optical mode to the second optical mode.

To relax the accuracy with respect to a positional deviation, and thus to reduce costs.

An optical waveguide is included that performs propagation only in a reference mode at a first wavelength. Communication is performed using light that has a second wavelength and includes a component of at least a first order mode in addition to a component of the reference mode. Here, the second wavelength is a wavelength that enables the optical waveguide to perform propagation in at least the first order mode in addition to the reference mode. For example, a light path adjuster that adjusts a light path such that input light is guided to a core of the optical waveguide, is further included.