Contentionless NxM Wavelength Cross Connect

Abstract

Technology for a contentionless N×M wavelength cross connect (WXC) device is disclosed herein. The WXC device includes multiple input and output wavelength dispersive elements and a cross connect assembly. The cross connect assembly includes multiple rows of incoming ports. For each individual wavelength of different wavelengths, split optical beams of the individual wavelength from the input wavelength dispersive elements reach a row of incoming ports corresponding to the individual wavelength. The cross connect assembly further includes transmissive active switching elements and multiple rows of outgoing ports. The transmissive active switching elements configured to dynamically establish at least one optical path between an incoming port within the row of incoming ports corresponding to the individual wavelength and an outgoing port within a row of output ports corresponding to the individual wavelength.

What is claimed is: 
     
         1 . A method for realizing functionalities of a reconfigurable optical add-drop multiplexer (ROADM) using a wavelength cross connect (WXC) device:
 receiving an input optical beam at one of input ports of the WXC device;   splitting the input optical beam into at least one express optical beam and at least one dropped optical beam;   splitting the dropped optical beam into dropped optical signals at different wavelengths and outputting some of the dropped optical signals from some of output ports of the WXC device;   receiving added optical signals at different wavelengths at some of the input ports of the WXC device and combining the added optical signals to the express optical beam; and   outputting the express optical beam from one of the output ports of the WXC device.   
     
     
         2 . The method of  claim 1 , further comprising:
 blocking optical signals at some wavelengths from the express optical beam.   
     
     
         3 . The method of  claim 1 , further comprising:
 performing dispersion compensation to the express optical beam.   
     
     
         4 . The method of  claim 1 , further comprising:
 imparting an optical gain to the express topical beam.   
     
     
         5 . The method of  claim 1 , further comprising:
 optically attenuating the express optical signal.   
     
     
         6 . The method of  claim 1 , further comprising:
 imparting optical gains to the added optical signals.   
     
     
         7 . A wavelength cross connect (WXC) device comprising:
 N input ports for receiving input optical beams;   M output ports for transmitting output optical beams;   N input wavelength dispersive elements, each of the N input wavelength dispersive elements separating by diffraction one of the input optical beams into L split optical beams at L wavelength channels;   a cross connect assembly having at least N×L incoming ports, multiple transmissive active switching elements, and at least M×L outgoing ports, wherein each of the N×L incoming ports belongs to one of the L wavelength channels, and each of the M×L outgoing ports belongs to one of the L wavelength channels, wherein a cross connect assembly includes attenuation components for attenuating the split optical beams;
 the N×L input port receiving the N×L split optical beams from the N input wavelength dispersive elements; 
 the transmissive active switching elements configured to dynamically control optical paths between the N×L incoming ports and the M×L outgoing ports such that anyone of the incoming ports of an individual wavelength channel of the L wavelength channels can establish an optical path with anyone of the outgoing ports of the individual wavelength channel at a moment; and 
   M output wavelength dispersive elements, each of the M output wavelength dispersive elements receiving L split optical beams from some of the M×L outgoing ports and combining the L received split optical beams into one of the output optical beams.   
     
     
         8 . The wavelength cross connect device of  claim 7 , wherein the input wavelength dispersive elements form a single input wavelength dispersive component, and the output wavelength dispersive elements form a single input wavelength dispersive component. 
     
     
         9 . The wavelength cross connect device of  claim 7 , wherein the split optical beams of a particular wavelength channel transport in the cross connect assembly without interference by other split optical beams of the particular wavelength channel. 
     
     
         10 . The wavelength cross connect device of  claim 7 , further comprising:
 incoming optical lens for guiding the split optical beams from the input wavelength dispersive elements to the incoming ports of the cross connect assembly; and   outgoing optical lens for guiding the split optical beams from the outgoing ports of the cross connect assembly to the outgoing wavelength dispersive elements.   
     
     
         11 . The wavelength cross connect device of  claim 7 , wherein the transmissive active switching elements comprises active liquid crystal based polarization grating cells. 
     
     
         12 . The wavelength cross connect device of  claim 7 , wherein the transmissive active switching elements comprises combinations of active liquid crystal based polarization grating cells and passive liquid crystal mesogen polarization grating cells. 
     
     
         13 . The wavelength cross connect device of  claim 7 , wherein the transmissive active switching elements comprises birefringent crystal. 
     
     
         14 . The wavelength cross connect device of  claim 7 , wherein the transmissive active switching elements comprises active matrix thin-film transistor liquid crystal cells. 
     
     
         15 . The wavelength cross connect device of  claim 7 , wherein the N input ports comprise collimators for collimating the input optical beams, and the M output ports comprise collimators for collimating the output optical beams. 
     
     
         16 . An optical switching device comprising:
 multiple input wavelength dispersive elements, each of the input wavelength dispersive elements receiving an input optical beam and splitting the input optical beam into multiple split optical beams of different wavelengths;   beam expansion units for expanding beam angles of the input optical beams;   a cross connect assembly including multiple rows of incoming ports, wherein for each individual wavelength of the different wavelengths, the split optical beams of the individual wavelength from the input wavelength dispersive elements reach a row of incoming ports corresponding to the individual wavelength;   the cross connect assembly further including active switching elements and multiple rows of outgoing ports, wherein the active switching elements configured to dynamically establish at least one optical path between an incoming port within the row of incoming ports corresponding to the individual wavelength and an outgoing port within a row of output ports corresponding to the individual wavelength; and   multiple output wavelength dispersive elements, each of the output wavelength dispersive elements combining some of the split optical beams into an output optical beam.   
     
     
         17 . The optical switching device of  claim 16 , wherein the output optical beam contain split optical beams from more than one different input optical beams. 
     
     
         18 . The optical switching device of  claim 16 , further comprising:
 input collimators for collimating the input optical beams; and   output collimators for collimating the output optical beams.   
     
     
         19 . The optical switching device of  claim 16 , further comprising:
 polarization diverse elements for polarizing the input optical beams.   
     
     
         20 . The optical switching device of  claim 16 , wherein the active switching elements comprise at least one transmissive active switching element or at least one reflective active switching element.