Tellium, Inc.

Bell Communications Research, Inc.

Telcordia Technologies, Inc.

Krishna Bala

Gee-Kung Chang

Georgios Nicos Ellinas

W John Tomlinson

John K Gamelin

Charles A Brackett

Robert R Cordell

Sung-Joo Yoo

Ghie Hugh Song

Chien-Chung Shen

Pankaj H Bhatt

John Yee-Keung Wei

Neophytos Andreas Antoniades

Michael Post

An optical cross-connect system and method allows service providers to economically and efficiently handle capacity upgrades to meet future demands. The optical cross-connect can be embodied as a three-stage switch having a first, a middle, and a last stage. Capacity upgrades may be accomplished by adding additional first and last stage switches to meet increased demand and by replacing the middle stage switches. Accordingly, the original first and last stage switches may be retained in the upgraded optical cross-connect. The resulting optical cross-connect may include both optical and electronic components and the upgrade may be performed without interrupting service.

Scalable optical cross-connect system and method transmitter/receiver protection

A wavelength-interchanging cross-connect for a wavelength-division multiplexing (WDM) optical communication system including both transparent optical paths and opaque paths through an electronic switching network, such as a high-speed digital cross-connect switch (DCS), including matching opto-electronic conversions of the data signal. All-optical switching is performed on the input and output sides, for example, by mechanically actuated fiber switches. The DCS, receiving optical inputs from the input optical switches and providing optical outputs to the output optical switches, performs switching in the electrical domain and can perform wavelength conversion of the signals passing through it. The DCS also provides for access to electrical add/drop lines for interfacing to a client. The transparent optical path, which can be either direct or through an optical switch, transfers a signal without regard to its format from the input to the output of the switching system. An algorithm is available for setting up the required connection through the different components.

Hybrid wavelength-interchanging cross-connect

An optical matrix protection system is described. Optical signals that are cross-connected by a N&times;N matrix switch are routed through alternative protection paths using an optical matrix protection system. The optical matrix protection system includes a N&times;1 optical switch and a 1&times;N optical switch. An input port of the 1&times;N optical switch is coupled to an output port of the N&times;1 optical switch. Input ports of the N&times;1 optical switch are connected to a plurality of 1&times;2 optical switches, which selectively switch input optical signals to either the N&times;N matrix switch or to the N&times;1 optical switch. Output ports of the 1&times;N optical switch are connected to a plurality of 2&times;1 optical switches, which selectively switch optical signals from either the N&times;N matrix switch or laid the 1&times;N optical switch to an output line.

Optical matrix protection system

A protection system for a micro electro-mechanical system (MEMS) cross-bar switch is described. Optical signals that are cross-connected by a N&times;N optical matrix switch are routed through alternative protection paths using protection switch elements. The protection switch elements are incorporated as part of the silicon wafer based fabricated structure that forms the N&times;N optical matrix. The protection switch elements enable the N&times;N optical matrix switch to recover from one or more failures in switch elements of the N&times;N optical matrix using alternative protection paths that have the same path length as the original optical path.

Protection for MEMS cross-bar switch

A reconfigurable multiwavelength network element includes a first demultiplexer unit for demultiplexing a first multiplexed optical signal from a first optical fiber into a first plurality of optical outputs; a second demultiplexer unit for demultiplexing a second multiplexed optical signal from a second optical fiber into a second plurality of optical outputs; a first multiplexer unit having first optical inputs for receiving signals to be multiplexed together; a second multiplexer unit having second optical inputs for receiving signals to be multiplexed together; and a cross-connect unit having first and second portions, the first portion directing signals received from at least a first one of the first plurality of optical outputs and a first one of the second plurality of optical outputs to a first one of the first optical inputs and a first one of the second optical inputs, the second portion directing signals received from at least a second one of the first plurality of optical outputs and a second one of the second plurality of optical outputs to a second one of the first optical inputs and a second one of the second optical inputs.

Reconfigurable multiwavelength network elements

A method of reconfiguring a multi-wavelength communication network. The transition includes determining the union of the old and new topologies. During at least the start of the transition, the network supports the union topology. New connections are connected according to the new topology, and the old topology, as its connections expire, is gradually removed. In allocating wavelengths to a new topology, two algorithms are developed which assign wavelengths which do not color clash with the wavelength assignments of the old topology.

Hitless reconfiguration of a wavelength division multiplexed optical

Techniques for physically implementing fiber ring networks which achieve full mesh connectivity, such networks including a 2-fiber WDM ring network composed of a clockwise ring and counter clockwise ring, and a 4-fiber WDM Self-Healing Ring network. The number of wavelengths required is derived for both odd and even number of nodes on the ring. To physically set-up all required connections in the network, optimal wavelength assignment algorithms are devised so that the wavelength assignment between nodes on the ring is systematic and engenders full mesh connectivity while avoiding any possible violation of the color clash constraint. An illustrative algorithm uses a simple matrix approach for calculating the interconnection arrangement.

Connection set-up and path assignment in wavelength division multiplexed

A wavelength-interchanging cross-connect for use as an optical switch within a wavelength-division multiplexing (WDM) communications network in which multiple optical carrier signals at different optical wavelengths are switched in an all-optical process according to their wavelength. The cross-connect of the invention further allows the optical wavelength of the signal being switched to be changed to another WDM wavelength. The cross-connect includes a series of multi-wavelength 2.times.2 spatial optical switches. One serial path is directly connected between the spatial switches. The other serial path leads through intermediate wavelength-interchanging modules that interchange the carrier wavelengths of at least one pair of signals. Preferably, the wavelength interchanging is performed by difference frequency generation relying on second-order non-linear susceptibilities and a pump signal providing parametric gain. The frequency of the pump signal is chosen to be the sum of the frequencies of whatever optical signals are to be interchanged, and more than one pair can simultaneously be interchanged. The placement of the pumping frequencies is determined by a design process using a modified version of a recursively designed Benes network. As a result, the wavelength-interchanging cross connect can be controlled by the well known looping algorithm known for Benes networks to be rearrangeably non-blocking.

Parametric wavelength interchanging cross-connect

A horizontally asymmetrically dilated optical switch comprising multiple stages of 2.times.2 optical switching units, especially electro-optic switching units such as acousto-optical tunable filters (AOTFs), which are electrically switchable between a bar state and a cross state to route and switch an optical signal through the switch. The switch is dilated that is, the switching units have an unused input or output so as to dump crosstalk terms into unused outputs. According to the invention, the interconnections between the switching units and their control are such that any optical signal and any crosstalk path passes through equal numbers of bar-state switches and of cross-state switches. Thereby, two advantages are gained. First, no switching path is transparent to a wide bandwidth so that noise cannot recirculate in an amplifying path and go into oscillation. Also, if one state or the other produces greater crosstalk, along no switching path is the larger term accumulated more than the smaller term.

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New York, NY, United States of America

Krishna Bala