Programmable wavelength router

DETAILED DESCRIPTION OF THE DRAWING 1.
Overview The preferred implementation of the present invention both demultiplexes (i.
e.
, spectrally separates) and routes (i.
e.
, spatially permutates) a wavelength division multiplexed (WDM) optical signal.
FIG.
1 illustrates in block diagram form the general functionality of the present invention.
A WDM signal 101 comprising multiple channels each channel with its own range of wavelengths or frequencies.
As used herein, the term "channel" refers to a particular range of frequencies or wavelengths that define a unique information signal.
Each channel is ideally evenly spaced from adjacent channels, although this is not necessary.
Uneven spacing may result in some inefficiency or complexity in design, but, as will be seen, the present invention can be adapted to such a channel system.
This flexibility is important in that the channel placement is driven largely by the technical capabilities of transmitters (i.
e.
, laser diodes) and detectors and so flexibility is of significant importance.
It should be understood that a full permutation routing of N channels would require N! possible output permutations which as not practical.
As used herein, the term permutation includes partial or incomplete permutation that is commonly used in signal routing.
Desirably, each of the multiplexed input channels can be selectively routed to any of the available output lines and all of the input channels can be placed on some line.
This requires that the router include at least the same number of outputs as the number of channels in the input signal, unless some of the output signals remain multiplexed as they leave the router.
The present invention is scaleable and so supports a greater number of output lines than the number of input channels in the multiplexed input signal.
In such cases, some of the output lines will not carry any signal which increases routing flexibility but is a less efficient use of hardware.
These and other equivalent variations from the specific examples described herein are considered equivalents to the wavelength router in accordance with the present invention