Nortel Networks Corporation

Peter D Roorda

Adrian Paul Sparks

Nigel Baker

Alan Frank Graves

Alan Glen Solheim

Robert William Spagnoletti

Frederick J Lalonde

The integrated photonic switch can be used in all-optical networks. incoming multiplexed signals from a number of input fiber ports are separated into their component wavelengths. Individual wavelengths are switched within the switch fabric towards the desired output, and the wavelengths are then multiplexed into WDM signals directed to the appropriate output ports. The multiplexer and demultiplexer are diffraction grating devices, integrated with the switch fabric. The switch fabric includes two matrices of 3-D MEMS mirrors arranged in the same plane, or in two parallel planes. The optical path between the input ports, the demultiplexer and the input matrix is pre-set so that each wavelength is incident on a certain mirror. Similarly, the geometry of the output matrix, the multiplexer and the output ports determines uniquely the wavelengths on a certain port. However, the position of the mirrors may be adjusted with a control system, so that the path of a wavelength within the switch fabric is adjustable, so that a wavelength input on a port may output the switch on any port.

Integrated photonic switch

To provide improved protection bandwidth efficiency for a fast recovery from a fault in an optical network, a protection ring for sharing between some of the protection paths has a pre-configured route so as to overlap on a given one of the links, with other protection paths or other rings. A selector for the given link selects which of the overlapping secondary paths is allocated to the given link at any time. Thus, two types of sharing of protection paths are combined to achieve more efficient use of protection bandwidth. The link selector can be controlled locally and so can operate more rapidly. The local control, essentially independent of the switches used to set up the secondary path through the network, makes the combination easier to scale to larger, more complex networks than shared rings alone.

Constrained optical mesh protection for transmission systems

A cross-connect switch for switching optical signals, in particular, Dense Wavelength Division Multiplexed (DWDM) signals is disclosed. The switch includes a switching matrix for each of the predetermined wavelengths of the DWDM signals. The switching matrices include Micro-Electro-Mechanical (MEM) systems which have optically reflective elements, typically mirrors, arranged in rows and columns for switching an incoming optical signal travelling along a row of such elements to an output port aligned with a column of the elements. The switch has input demultiplexers to split an incoming DWDM signal into its component channel wavelengths, each of which is directed to a switching matrix where it is switched to an output port and recombined into an outgoing DWDM signal by a multiplexer before being transmitted out of the switch. A wavelength-converting switch, connected across the switching matrices, is also included for switching channels between wavelengths.

Switch for optical signals

An optical switch comprising at least two segments, each segment having a respective input and a respective output, arranged such that in use if a first segment is removed, a second segment can operate as a pass-through device.

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Hertford, United Kingdom

Peter D Roorda