Wavelength division multiplexed optical communication system having a reconfigurable optical switch and a tunable backup laser transmitter

In a WDM optical communication system that includes a plurality of nodes interconnected by communication links, a node comprising:

• a reconfigurable optical switch having a plurality of input ports and at least one output port;
• a plurality of transmitters each coupled to one of the input ports of the optical switch, each of said transmitters generating an information-bearing optical signal at a different channel wavelength from one another, said reconfigurable optical switch being adaptable to receive at any of the input ports any of the channel wavelengths at which the plurality of transmitters operate and direct said channel wavelengths to said al least one output port;
• at least one backup transmitter coupled to one of the input ports of the optical switch, said backup transmitter including a tunable laser tunable to any of the channel wavelengths at which the plurality of transmitters operate;
• wherein said reconfigurable optical switch includes;
• at least one wavelength selective element that selects at least one channel wavelength from among any of the channel wavelengths received at any of the input ports,
• wherein said at least one wavelength selective element comprises a plurality thin film filters each transmitting therethrough a different one of the channel wavelengths and reflecting the remaining channel wavelengths;
• and
• a plurality of optical elements associated with said at least one wavelength selective element, each of said optical elements directing one of the selected channel wavelengths selected by the associated at least one wavelength selective element to said output port independently from every other channel wavelength, wherein said selected channel wavelengths directed to said output port are combined on said output port, and
• further comprising a free space region disposed between the input ports and the wavelength selective elements
• wherein said free space region comprises an optically transparent substrate having first and second parallel surfaces, said wavelength selective clement includes a plurality of wavelength selective elements arranged in first and second arrays extending along the first and second parallel surfaces, respectively.

In a WDM optical communication system that includes a plurality of nodes interconnected by communication links, a node comprising:

• a reconfigurable optical switch having (i) N input ports for receiving a WDM optical signal having up to (N−1) channel wavelengths (ii) at least one output port, where N is greater than or equal to 2 and (iii) a switching fabric that includes at least (N−1) optical elements each directing a selected one of the channel wavelengths between the input ports and the at least one output port;
• N transmitters respectively coupled to the N input ports of the optical switch, said transmitters each including a tunable laser tunable to any at the (N−1) channel wavelengths, said reconfigurable optical switch being adaptable to receive at any of the input ports any of the channel wavelengths at which the plurality of transmitters operate and direct each of the channel wavelengths to said at least one output port by reconfiguration of the optical clement respectively directing the channel wavelength;
• and
• at least (N−1) wavelength selective elements that each select at least one channel wave1ength from among any of the channel wavelengths received at any of the input ports and wherein the (N−1) optical elements are respectively associated with said (N−1) wavelength selective elements, each of said optical elements directing one of the selected channel wavelengths selected by the associated at least one wavelength selective element to said output port independently from every other channel wavelength, wherein said selected channel wavelengths directed to said output port are combined on said output port,
• wherein said optical elements are reflective mirrors that arc selectively tiltable in a plurality of positions such that in each of the positions the mirrors reflect the channel wavelength incident thereon to the output port.

In a WDM optical communication system that includes a plurality of nodes interconnected by communication links, a node comprising:

• a reconfigurable optical switch having (i) N input ports for receiving a WDM optical signal having tip to (N−1) channel wavelengths (ii) at least one output port, where N is greater than or equal to 2 and (iii) a switching fabric that includes at least (N−1) optical elements each directing a selected one of the channel wavelengths between the input ports and the at least one output port;
• N transmitters respectively coupled to the N input ports of the optical switch, said transmitters each including a tunable laser tunable to any of the (N−1) channel wavelengths, said reconfigurable optical switch being adaptable to receive at any of the input ports any of the channel wavelengths at which the plurality transmitters operate and direct each of the channel wavelengths to said at least one output non by reconfiguration of the optical element respectively directing the channel wavelength;
• at least (N−1) wavelength selective elements that each select at least one channel wavelength from among any of the channel wavelengths received at any of the input ports and wherein the (N−1) optical elements are respectively associated with said (N−1) wavelength selective elements, each of said optical elements directing one of the selected channel wavelengths selected by the associated at least one wavelength selective element to said output port independently from every other channel wavelength, wherein said selected channel wavelengths directed to said output port are combined on said output port;
• and
• a free space region disposed between the input ports and the wavelength selective elements,
• wherein said free space region comprises an optically transparent substrate having first and second parallel surfaces, said wavelength selective element includes a plurality of wavelength selective elements arranged in first and second arrays extending along the first and second parallel surfaces, respectively.