Data center network architectures, systems, and methods that can reduce the cost and complexity of data center networks. Such data center network architectures, systems, and methods employ physical optical ring network and multi-dimensional network topologies and optical nodes to efficiently allocate bandwidth within the data center networks, while reducing the physical interconnectivity requirements of the data center networks. The respective optical nodes can be configured to provide various switching topologies, including, but not limited to, chordal ring switching topologies and multi-dimensional chordal ring switching topologies.

Methods and apparatus for add-drop multiplexing in all optical networking are provided. A tunable optical filter is controlled to drop a first portion of an incoming optical signal in a first wavelength band and pass a second portion of the incoming optical signal in a second wavelength band. The dropped first portion is distributed among local drop optical output ports with a demultiplexer. A multiplexer combines local add optical input signals in a third wavelength band into an add optical input signal and the tunable optical filter is controlled to add the add optical input signal to the passed second portion of the incoming optical signal. The tunable optical filter is configured to lower an optical loss for the passed second portion of the incoming optical signal at the account of a corresponding increase of an optical loss in the dropped first portion and/or the add optical input signal.

A method and apparatus for approaches for troubleshooting optical networks, particularly ROADM-based networks is described. The method includes designating a first port, of an optical communication node of a transport network, as an ingress for a loop-back optical signal to troubleshoot the transport network, designating a second port, of the optical communication node, as an egress for the loop-back optical signal, and establishing a loop-back connection between the first port and the second port to transport the loop-back optical signal.

A wavelength division multiplexed optical communication system includes a plurality of optical line terminals which may be part of separate in service networks, each having a line interface and an all-optical pass-through interface including a plurality of pass-through optical ports, and each also including a plurality of local optical ports which are connectable to client equipment and an optical multiplexer/demultiplexer for multiplexing/demultiplexing optical wavelengths. The optical multiplexer/demultiplexer may include one or more stages for inputting/outputting individual wavelengths or bands of a predetermined number of wavelengths, or a combination of bands and individual wavelengths. At least one of the pass-through optical ports of an optical line terminal of one network may be connected to at least one of the pass-through optical ports of an optical line terminal of another network to form an optical path from the line interface of the optical line terminal of the one network to the line interface of the optical line terminal of the another network to form a merged network. The use of such optical line terminals allows the upgrading and merging of the separate networks while in service.

An optical switch, comprising: a first optical waveguide, a first optical add path, a second optical add path and a micro-ring resonator. The micro-ring resonator is operable to add a first optical signal at a preselected wavelength received from the first optical add path to the first optical waveguide to travel in a first direction through the first optical waveguide. The micro-ring resonator is further operable to add a second optical signal at the preselected wavelength received from the second optical add path to the first optical waveguide to travel in a second direction through the first optical waveguide opposite to the first direction. There is also provided an optical drop switch, an optical switching apparatus, an optical communications network node and an optical communications network.

A flexible grid optical transmitter communicatively coupled to an optical network includes a coherent optical transmitter configured to generate a signal at a respective center frequency on an optical spectrum and spanning n bins about the respective center frequency, wherein n is an integer greater than 1, wherein the respective center frequency and the n bins are utilized to perform Operations, Administration, Maintenance, and Provisioning (OAM&P) functions. The respective center frequency and the n bins are specified to the coherent optical transmitter by a management system for the OAM&P functions. Each of the n bins can include a same arbitrary size, and the arbitrary size can be greater than or equal to 1 GHz and less than or equal to 12.5 GHz.

Techniques for communications using optical fiber are disclosed. An optical add/drop multiplexer (OADM) node includes an interface to a first fiber pair connecting a first trunk station and a second trunk station. The OADM node further includes an interface to a second fiber pair connecting the first trunk station and the second trunk station with a branch station. The OADM node includes a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station. Other embodiments are described and claimed.

Flexible optical spectrum management systems and methods in an optical network including a plurality of interconnected network elements include determining an associated frequency/wavelength center and one or more bins for each of one or more traffic carrying channels on each of a plurality of optical fibers in the optical network; and managing the one or more traffic carrying channels on the plurality of optical fibers using the one or more bins of bins and the associated frequency/wavelength center, wherein at least one of the one or more traffic carrying channels comprises a coherent optical signal occupying a flexible spectrum on the plurality of optical fibers.

A flexible grid optical transceiver communicatively coupled to an optical network includes a coherent optical transmitter configured to generate a transmit signal at a first frequency/wavelength center and spanning a first one or more bins of optical spectrum; and a coherent optical receiver configured to receive a receive signal at a second frequency/wavelength center and spanning a second one or more bins of optical spectrum, wherein a size of each of the first one or more of bins and the second one or more of bins is based on a required roll off of a wavelength selective component in the optical network.

Systems and methods for routing wavelengths in an optical network include responsive to a path request for a wavelength or group of wavelengths, determining a path through the optical network; determining a location on the path where wavelength blocking should occur to form a loop-free path in the optical network; and setting the wavelength blocking at the location. The optical network can utilize a broadcast and select architecture and the wavelength blocking is configured to prevent the wavelength or group of wavelengths from looping back on a port where the wavelength or group of wavelengths has already been received on. The optical network can utilize an all-broadcast architecture and the wavelength blocking is configured to prevent multiple paths for the wavelength or group of wavelengths by constraining the wavelength or group of wavelengths to a single path through the optical network.