In a WDM optical communication system that includes a plurality of nodes
interconnected by communication links, a node is provided that includes a
reconfigurable optical switch having a plurality of input ports and at
least one output port. The node also includes a plurality of transmitters
that are each coupled to one of the input ports of the optical switch.
Each of the transmitters generate an information-bearing optical signal
at a different channel wavelength from one another. The reconfigurable
optical switch is adaptable to receive at any of the input ports any of
the channel wavelengths at which the plurality of transmitters operate
and direct the channel wavelengths to the output port. At least one
backup transmitter is coupled to one of the input ports of the optical
switch. The backup transmitter includes a tunable laser tunable to any of
the channel wavelengths at which the plurality of transmitters operate.
The 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. The
switch also includes a plurality of optical elements associated with the
wavelength selective elements, Each of the optical elements direct one of
the selected channel wavelengths selected by the associated wavelength
selective element to the output port independently from every other
channel wavelength. The selected channel wavelengths directed to the
output port are combined on the output port.