An apparatus for management of a spectral capacity of a wavelength division multiplexing, WDM, system includes at least one pair of transmission fibers provided for transporting optical signals. Each transmission fiber of a transmission fiber pair is connected to a first port of an optical circulator having at least two additional ports and adapted to transmit an incoming optical signal entering one of its ports via its next port. WDM subsystems configured with counter-propagating assignable wavelengths are connected to associated ports of the optical circulator of the apparatus.

An example reconfigurable optical add/drop multiplexer includes: optical fibers, X first wavelength selective switches, and Y wavelength add/drop modules. The X first wavelength selective switches correspond to W directions. The W directions include a first direction and a second direction. The first direction corresponds to P first wavelength selective switches among the X first wavelength selective switches. The second direction corresponds to Q first wavelength selective switches among the X first wavelength selective switches, where P+Q is less than or equal to X. A first wavelength add/drop module is connected to A of the P first wavelength selective switches by using one or more first optical fibers, and connected to B of the Q first wavelength selective switches by using one or more second optical fibers, where the first wavelength add/drop module is one of the Y wavelength add/drop modules, A is less than P.

Optical wavelength division multiplexing (WDM) devices include an optical chip having a number of waveguides therein, with a common optical fiber and single wavelength channel optical fibers optically coupled to the waveguides. Wavelength sensitive filters are disposed between the chip and the fibers, or across waveguides within the chip to reflect light at certain wavelengths and to transmit light at other wavelengths. In sonic embodiments, all of the fibers are located at the same end of the chip, in others the common fiber is located at one side of the chip and the single channel fibers located at another side, while in others the common fiber is located at a first side of the chip and the single channel fibers are located either at the first side of the chip or at a second side of the chip.

Signal distribution arrangements are assembled by selecting a terminal body and a tap module combination that provides the desired signal strength at the intended position in an optical network. Each terminal body includes an input connection interface, a pass-through connection interface, a module connection interface, and multiple drop connection interfaces. Each tap module houses an optical tap having an asymmetric split ratio. Most of the optical signal power received at the signal distribution arrangement passes to the pass-through connection interface. A portion of the optical signal power is routed to the drop connection interfaces (e.g., via a symmetrical optical power splitter). The tap module and terminal body combination are selected based on the desired number of drop connection interfaces and to balance the asymmetric split ratio with the symmetric split ratio.

A fiber-optic communication apparatus includes an optical monitor that monitors a WDM signal in. which optical signals of multiple channels are multiplexed, a processor that calculates a control value for controlling an optical power of the WDM signal, based. on a power spectrum detected by the optical monitor, in a unit interval of frequency narrower than a channel bandwidth of the WDM signal, and an optical power adjusting mechanism that adjusts the optical power of the WDM signal in the unit interval of frequency based on the control value.

An optical switching apparatus includes an input port, a dispersion component, a first filter, a redirection component, and output ports. The input port enables a first and a second beam to be incident onto the dispersion component, which decomposes the first and the second beams respectively into a plurality of first and second sub-beams, where the plurality of first sub-beams and second sub-beams belong to different bands. The first filter separates transmission directions of the plurality of first and second sub-beams into different transmission directions in a first direction (X) based on the different bands, enables the plurality of first and second sub-beams respectively to be incident onto a first area and a second area of the redirection component, where the first and second areas are separated in the first direction.

Aspects of the present disclosure describe techniques for controlling coherent crosstalk errors that occur in multi-channel acousto-optic modulators (AOMs) by applying cancellation tones to reduce or eliminate the crosstalk errors. For example, a method and systems are described that include applying a first radio frequency (RF) tone to generate a first acoustic wave in a first channel of the multi-channel AOM, wherein a portion of the first acoustic wave interacts with a second channel to cause a crosstalk effect, and applying a second RF tone to generate a second acoustic wave in the second channel, wherein the second acoustic wave reduces or eliminates the crosstalk effect caused by the portion of the first acoustic wave.

Systems and methods are provided for controlling one or more optical amplifiers of a C+L band photonic line system (30) of a telecommunications network in which C-band signals and L-band signals may be transmitted. In one implementation, a method (130) may execute a traffic managing module (23). When executed, the traffic managing module (23) may be configured to enable a processing device (12) to calculate (132) a gain correction profile based on a difference between a saved baseline transmission profile (84) and a measured transmission profile (94) of a surviving band of a photonic line system (30) when another band of the photonic line system (30) is missing or impacted. The traffic managing module (23) may further be configured to enable the processing device (12) to apply (134) the gain correction profile to a respective optical amplifier (46) of the photonic line system (30) to compensate for the difference.

An optical communications network comprises optical data links interconnected by add-drop nodes, the optical data links comprising data channels. The data channels are allocated into equal-sized bins. In response to a first data channel request between a given source-destination pair, one of the equal-sized bins is assigned to the data channel request. In response to requests for additional bandwidth for the same source-destination data channel request, unused channels within the assigned equal-sized bin are allocated to the data channel request. In response to subsequent data channel requests between different source-destination pairs, additional unallocated equal-sized bins are assigned to the subsequent data channel requests. In response to subsequent data channel requests when resource sharing for one equal-sized bin, data channels in the last equal-sized bin are assigned using the reverse channel assignment process. Reverse channel assignment can also be used for other bins as an option.

A transmission device includes a symbol generator that generates a modulation symbol by mapping transmission data to a signal point arranged in a two-dimensional or three-dimensional color space; and an outputter that outputs an optical signal modulated according to the modulation symbol.