Optical wavelength-space cross-connect switch architecture

Details Optical wavelength-space cross-connect switch architecture Optical wavelength-space cross-connect switch architecture

1999-08-09

2001-02-20

Palmer, Phan T. H. (Department: 2874)

Optical waveguides

With optical coupler

Switch

C385S024000, C385S046000, C385S016000, C385S020000, C359S199200, C359S199200

Reexamination Certificate

active

06192172

ABSTRACT:

TECHNICAL FIELD
This invention relates to optical networks, and more particularly, to optical cross-connect switches used for routing multi-wavelength optical signals.
BACKGROUND OF THE INVENTION
Optical networks are widely used to transport large volumes of telecommunications traffic. For example, systems employing wavelength division multiplexed (WDM) technology are capable of supporting dozens of communications channels transported at different wavelengths on just a single optical fiber.
In a multi-fiber network, some of the many channels on individual optical fibers may need to be selectively routed to other fibers. Selective routing may be required, for example, to balance communications traffic, or to avoid an out-of-service leg in the optical network. Such routing can be facilitated by interconnecting the individual optical fibers via an optoelectronic cross-connect switch. However, these switches suffer the disadvantage of requiring the multiple conversion of WDM signals first from optical form into electronic form and then back into optical form. It would be advantageous if the optical switching could be performed without these conversions.
Some cross-connect switch fabrics have been devised that enable WDM signals to be optically switched (see, e.g., U.S. patent application Ser. No. 09/123,085 now U.S. Pat. No. 6,067,389, entitled WAVELENGTH-SELECTIVE OPTICAL CROSS-CONNECT, assigned to Lucent Technologies Inc., having a filing date of Jul. 27, 1998). These fabrics typically use various optical filter technologies to “select” the optical channels to be routed (such filters also being referred to as “wavelength-selective elements”). However, filter performance factors such as insertion loss, “blue” wavelength loss and tuning range effectively limit the number of communications channels that can be supported by each fabric. For example, in wavelength-selective cross-connect (WSXC) fabrics employing tunable fiber Bragg gratings as wavelength selective elements to select optical channels with 50 gigahertz spacing, experience suggests a practical limit of about ten wavelength-selective elements per path through the fabric. As a result, optical WSXC fabrics have not been used to support large-scale optical cross-connect switch applications.
Thus, in order to employ current optical switching components (such as WSXC fabrics) in large-scale optical cross-connect switch applications, an optical cross-connect switch architecture is required that is capable of switching optical signals with a large number of optical channels while requiring only a small number of wavelength-selective elements on each signal path through the switch.
SUMMARY OF THE INVENTION
The number of wavelength-selective elements required on each signal path through an optical cross-connect switch is substantially reduced in a novel optical cross-connect switch architecture employing multiple WSXC fabrics. One or more optical channel distributors each receive a multi-wavelength optical signal as input. Each signal contains a plurality of channels, each associated with one or a plurality of wavelengths. Each distributor distributes each channel in its associated multi-wavelength input signal to one of a plurality P of WSXC fabrics. Each WSXC fabric is arranged to receive channels from the one or more distributors that are associated with a unique subset of the plurality of wavelengths.
Upon receiving the distributed channels, each WSXC fabric employs wavelength-selective elements on each of a plurality of WSXC fabric cross-paths to route each received channel to one of a plurality of optical combiners. Each combiner then combines the channels it receives from each WSXC fabric to produce and output a multi-wavelength optical signal with a full complement of channels. By employing this architecture, the number of channels carried by each WSXC fabric cross-path is reduced by a factor of P over the number of channels present in the multi-wavelength input and output signals.
In an exemplary embodiment of the invention, the distributors comprise optical slicers and the wavelength-selective elements comprise tunable fiber Bragg gratings (FBGs). The FBGs are tunable to reflect or pass optical signals in associated channels. The optical slicers operate to cause the optical channels associated with each multi-wavelength input signal to be allocated to the individual WSXC fabrics such that spacing between adjacent channels on each fabric is increased over spacing between adjacent channels in the input signal. This added spacing provides a “parking space” to which FBGs associated with adjacent channels may be tuned, thus enabling signals to pass in the adjacent channels. In addition, the added spacing reduces the effects of overlapping “blue” wavelength losses contributed by the FBGs on each path.


REFERENCES:
patent: 5446809 (1995-08-01), Fritz et al.
patent: 5694234 (1997-12-01), Darcie et al.
patent: 5712932 (1998-01-01), Alexander et al.
patent: 6055348 (2000-04-01), Jin et al.
patent: 6067389 (2000-04-01), Fatehi et al.
Dan Sadot et al., “Tunable Optical Filters for Dense WDM Networks”, IEEE Communicaitons Magazine, Dec. 1998, pp. 50-55.
Daniel Y. Al-Salameh et al., “Optical Networking”, Bell Labs Technical Journal, vol. 3, No. 1, Jan./Mar. 1998, pp. 39-61.
U. S. Patent application of S. Jin 160-9, entitled “Tunable Grating Device and Optical Communication Devices and Systems Comprising Same”, filed on Sep. 23, 1999, Serial No. 09/159,380 Now US Patent No. 6,055,348.
U. S. Patent Application of M. T. Fatehi 23-27, entitled Wavelength-Selective Optical Cross-Connect, Serial No. 09/123,085, filed on Jul. 27, 1998 Now US patent No. 6,067,389.

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