Consistent with the present disclosure, an optical switch is provided that switches multiple wavelength division multiplexed (WDM) optical signals. Each of the WDM signals includes optical signals having the same wavelengths. The WDM signals are supplied to optical splitters, which supply power split portions of the WDM signals to corresponding optical gates. Groups of the optical gates are associated with a corresponding switching block, which may include a cyclical arrayed waveguide grating (AWG), and the optical gates within each group are controlled so that one gate passes a received WDM signal portion while the remaining optical gates in the group are in a blocking configuration. As a result, the WDM portion received by the non-blocking gate is demultiplexed in the switching block and each of the wavelength components that constitute the selected WDM portion are supplied to corresponding outputs within the switching block. In a later time interval, a different optical gate may be rendered non-blocking so that a different WDM signal portion, supplied from a different optical splitter and carrying different information over the same wavelengths, may be input to the switching block. Thus, by controlling the optical gates, different WDM signal portions may be switched to, and thus demultiplexed by, a particular switching block. In addition, portions of the same WDM signal may be selectively supplied to different AWGs by appropriately control of the optical gates.

An optical communications system includes an optical transmitter and an optical receiver optically coupled to an optical combiner/splitter, the combiner/splitter coupled to optical media; and, another optical transmitter and another optical receiver optically coupled to another optical combiner/splitter, the another combiner/splitter remotely coupled to the optical media; wherein the optical transmitter and the another optical transmitter are configured to transmit optical signals at substantially the same wavelength.

To use a plurality of wavelength bands, this seabed branching device comprises: a first demultiplexing unit that demultiplexes a wavelength multiplexed optical signal, which was input from a first terminal, into a first wavelength multiplexed optical signal and a second wavelength multiplexed optical signal; an optical add/drop unit that outputs at least a third wavelength multiplexed optical signal included in the first wavelength multiplexed optical signal to a second terminal station, and outputs at least a fifth wavelength multiplexed optical signal by multiplexing a fourth wavelength multiplexed optical signal included in the first wavelength multiplexed optical signal and a wavelength multiplexed optical signal input from the second terminal station; and a first multiplexing unit that multiplexes the second wavelength multiplexed optical signal and the fifth wavelength multiplexed optical signal, which was input from the optical add/drop unit, and outputs the result to a third terminal station.

Systems and methods for data transport, including submarine reconfigurable optical add/drop multiplexers, branching units configured to receive signals from trunk terminals (TTs), and dummy light filters configured to pass useful signals through the filters, and to reflect dummy light. Optical interleavers are configured to separate useful signals into two or more groups of optical channels, and the optical channels are set to a frequency of either a left or a right portion of a total channel bandwidth. De-interleavers merge signal groups together from trunk terminals, and lasers at each of the transponders at the source terminals are configured to adjust a destination of a channel by fine tuning a frequency or wavelength of the one or more signals.

A telecommunications module includes an optical wavelength division multiplexer/demultiplexer configured to demultiplex a first optical signal input into the telecommunications module into a plurality of different wavelengths, a fiber optic splitter configured to split a second optical signal input into the telecommunication module into a plurality of optical signals, and a plurality of optical add/drop filters, each of the optical add/drop filters configured to combine one of the optical signals that has been split by the fiber optic splitter and one of the wavelengths that has been demultiplexed by the optical wavelength division multiplexer/demultiplexer into a combination output signal that is output from the telecommunications module.

An optical add/drop multiplexer branching apparatus is provided in the embodiments of the present invention, where the optical add/drop multiplexer branching unit includes: a trunk input end, a branch input end, a trunk output end, a branch output end, an optical add/drop multiplexer, a first coupler, a first detection circuit, and a control circuit, where the optical add/drop multiplexer includes an optical switch. A detection circuit detects whether a fault occurs in a trunk, and in a case in which a fault occurs in the trunk, a working mode is switched from a first working mode to a second working mode, to implement automatic redundancy on the trunk and ensure normal communication on a branch.

There is provided a multi-flow optical transceiver that includes (a) a plurality of wavelength-tunable light sources, (b) a plurality of optical modulation units which modulates light with an input signal, (c) an optical multiplexing/demultiplexing switch which couples light from at least one of the wavelength-tunable light sources to at least one of the optical modulation units with any power, (d) an optical coupling unit which couples a plurality of lights, modulated by a plurality of the optical modulation units, to at least one waveguide, (e) at least one multiple carrier generating unit which generates multiple carries, arranged at equal frequency intervals, from light of the wavelength-tunable light source, and (f) a wavelength separation unit which branches the multiple carriers from the multiple carrier generating unit for each wavelength.

Embodiments of the present invention provide a reconfigurable optical add-drop multiplexer apparatus, and relate to the field of communications, so as to solve the problem of inconvenient line failure detection. The ROADM apparatus includes: a first ROADM, a second ROADM, one splitting coupler, four optical amplifiers, and four couplers. The embodiments of the present invention are used in a communications line architecture.

A modified optical PAM communication system using multiple laser sources to generate each amplitude level. The systems can be applied separately or in conjunction with another modulation system such as SDM, MDM, WDM, TDM, or other communication systems. In an embodiment, a PAM-4 system will increase data rate by a factor of two, but more complicated schemes using more lasers can be utilized to generate higher efficiency schemes. For example, a 25 Gbps NRZ signal will give 50 Gbps PAM-4 signal and higher laser systems can generate PAM-8 or PAM-16 for 75 and 100 Gbps systems respectively. These can be further applied to SDM systems to generate higher data rates equivalent to the number of SDM channels multiplied by the PAM efficiency. In embodiments, the invention may combing PAM with WDM and SDM to achieve multiple bits per symbol.

A method includes establishing an extended optical spectrum having multiple channels for transmission of signals within an optical network. The extended optical spectrum includes at least the C-band (i.e., 1530 nm to 1565 nm) plus one or more sub-bands each having a range of wavelengths including at least one optical channel outside the range of the C-band. The method also includes segmenting the extended optical spectrum into a local band and an express band having different transmission specifications. The local band is configured for transmission of signals between nodes having a relatively shorter distance therebetween and the express band is configured for transmission of signals between nodes having a relatively longer distance therebetween. A combination of the sub-bands covers less than the L-band having a range of wavelengths from 1565 nm to 1625 nm and/or less than the S-band having a range of wavelengths from 1460 nm to 1530 nm.