The outage probability in an under-addressed optical MIMO system may be reduced by configuring a spatial-mode coupler at a transmitter and/or a spatial-mode separator at a receiver to dynamically change its spatial-mode configuration on a time scale that is shorter than the channel coherence time. Provided that the MIMO system employs an FEC code that has a sufficient error-correcting capacity for correcting the amount of errors corresponding to an average state of the MIMO channel established between the transmitter and receiver, this relatively fast dynamic change tends to reduce the frequency of events during which the number of errors per FEC-encoded block of data exceeds the error-correcting capacity of the FEC code.

A system and method for securing communication over an optical fiber are disclosed. The system includes a transmit spatial multiplexer configured to couple a plurality of optical signals into respective ones of a plurality of spatial paths of an optical fiber, each of the spatial paths being able to carry an optical signal; wherein at least one of the plurality of optical signals is an optically modulated version of a desired sequence of information that is intended to be transferred over the optical fiber; and wherein at least one of the plurality of optical signals is an optical chaff signal; whereby a tap along the fiber cannot determine the transmitted desired sequence of information.

A SDH receiver which comprises a first polarization beam splitter 11, a second polarization beam splitter 13, a first separator 15, a second separator 17, a third separator 19, a fourth separator 21, a first 90-degree polarization rotor 23, a second 90-degree polarization rotor 25, a first hybrid detector 31, a second hybrid detector 33, a third hybrid detector 35, a fourth hybrid detector 37, and a signal processor 39.

An optical device (501) is disclosed, including a spatial multiplexer/demultiplexer (520) and an optical splitter (510). The optical splitter (510) is an M:N optical splitter, M is greater than or equal to 2, and N is greater than or equal to M. M is a quantity of common ports of the optical splitter (510), and N is a quantity of drop ports of the optical splitter (510). The spatial multiplexer/demultiplexer (520) includes one common port (521) and M drop ports (522-1 to 522-M). The M drop ports of the spatial multiplexer/demultiplexer (520) are connected to the M common ports of the optical splitter (510). The common port (521) of the spatial multiplexer/demultiplexer (520) has a capability of transmitting optical signals in multiple spatial modes.

The present disclosure relates to system applications of multicore optical fibers. One embodiment relates to a base transceiver station for a wireless telecommunication system comprising a plurality of antenna units arranged in a MIMO configuration and adapted for transmission and/or reception of radio-frequency signals, an optical transmitter in the form of an electro-optic conversion unit for each of said plurality of antenna units, each electro-optic conversion unit adapted for converting an RF signal into an optical signal, a plurality of a single core optical fibers for guiding the optical signals, and at least one first space division multiplexing (SDM) unit adapted for multiplexing said single core optical fibers into respective individual cores of a multicore fiber, or into respective individual modes of a multimode fiber.

Optical amplifier assembly for spatial division multiplexing (SDM) optical communication systems. Each optical amplifier assembly includes a single pump assembly configured for causing amplification of signals traveling on separate fiber paths in different directions. Each fiber path includes a plurality of spatial dimensions. The single pump assembly includes a plurality of pump sources to provide redundancy and the optical amplifier assembly further includes splitters for splitting outputs of the pump sources to amplifiers coupled to the different spatial dimensions. Different modulation formats may be used on the different spatial dimensions with different pump power being provided to each of the modulation formats. Amplifiers with complementary outputs may be coupled to average out gain deviations.

A method for transmitting an orthogonal function processed signal over a communications link on a fiber involves generating at least one mode crosstalk matrix illustrating mode crosstalk between transmitted modes and adjacent modes within the fiber. Adjacent modes to be multiplexed together are selected based on entries within the generated mode crosstalk matrix being less than or equal to a predetermined value. The transmitted modes and the selected adjacent modes are multiplexed together into the orthogonal function processed signal for transmission on the communications link on the fiber.

An optical node may include an optical switch and an optical add drop multiplexer (OADM). The optical switch may receive, via a space-division multiplexing (SDM) link that carries optical signals via multiple SDM elements, an optical signal to be switched from a first SDM element to a second SDM element. The multiple SDM elements may include multiple cores of a multi-core fiber, multiple modes of a multi-mode fiber, or multiple fibers of a fiber bundle. The optical switch may switch the optical signal from the first SDM element to the second SDM element. The OADM may add optical signals to an optical network or drop optical signals from the optical network via one or more SDM links that include the SDM link.

A method and system for distributed spatial mode processing is disclosed. A number of optical signals are received over an optical link. Each optical signal is received via a respective one of a number of spatial modes of the optical link. The optical link includes a particular spatial mode not used for the receiving. A first one of the number of optical signals received from a first one of the number of spatial modes is transferred to a second one of the number of spatial modes via the particular spatial mode, wherein the first one of the number of optical signals is transmitted via the second one of the number of spatial modes.

Systems and methods include an optical transceiver configured to connect to a fiber cable having a plurality of fiber cores, the optical transceiver including a plurality of transmitters, and a plurality of receivers, wherein the transmitters connect to a first set of the fiber cores in the fiber cable and the receivers connect to a second set of the fiber cores of the fiber cable. The optical transceiver including an array composed of the elements where each element consists of a LED and a Photodetector connected to a programmable wire such that a training algorithm selects which wires become active in the data path. Associated circuitry such as drivers for LEDs and TIAs for PDs are also part of each element.