Multiple wavelength optical interferometer switch

#This invention pertains to optical communications systems, in general, and to interferometers used in communications systems, in particular.

#An optical cross-connect device is functionally a four port device that works with optical signals comprising a plurality of different wavelengths. An optical cross-connect has an input port, a through port, an add port, and a drop port. Multiplexed wavelength optical signals at the input port are coupled to the through port. The use of add and drop ports allow optical signals at specific wavelengths to be “added” in place of the corresponding wavelength optical signals in the input port signals that in turn are switched to the drop port. This enables optical wavelength components signals to be added and dropped to/from multiplexed wavelength optical signals. An ideal optical cross-connect device is capable of dropping any combination of wavelengths from the input port to the drop port and adding any wavelengths combinations from an add port to the through port.

#Wavelength routing optical cross-connect arrangements presently available separate incoming wavelengths received at inputs by utilizing DWDM demultiplexing. Typically large-scale optical switch matrices are utilized to switch and route the de-multiplexed single wavelength signals. In one arrangement micro-machined mirrors are utilized in what is referred to as MEM technology. In other arrangements, total internal reflection techniques are utilized with bubble or liquid crystal displays. These prior arrangements combine out-going wavelengths using DWDM multiplexers.

#The invention will be better understood from a reading of the following detailed description in conjunction with the drawing in which like reference designations are used in the various drawing figures to identify like elements, and in which:

#FIG. 1 is a block diagram illustrating wavelength routing optical cross-connect functions;

#FIG. 2 is a block diagram illustrating a wavelength routing optical cross-connect utilizing prior art switch matrix technology;

#FIG. 1 illustrates the functionality of a wavelength routing optical cross-connect 100. Optical cross-connect 100 has an input port 101 that can receive a number, n, optical wavelength components λ1, λ2, . . . , λn−1, λn. Optical cross-connect 100 can couple all of the wavelength components λ1, λ2, . . . , λn−1, λn to a through port 103. Selected wavelength components may be substituted for the wavelength components at through port 103 by via add port 107. In addition, any one or more of the wavelength components λ1, λ2, . . . , λn−1, λn may be “dropped” from the wavelength components transferred from input port 101 to through port 103 and outputted at drop port 105. Wavelength optical cross-connect 100 is capable of dropping any combination of wavelength components from input port 101 to drop port 105 and is capable of adding any wavelength component combinations from add port 107 to through port 103. Typically, when wavelength components are added, the corresponding wavelength components in the input optical signals are dropped.

#FIG. 2 illustrates wavelength routing optical cross-connect 200 utilizing prior art switch matrix technology. An optical switch matrix 210 is utilized. To provide for “n” multiplexed wavelengths, a complex n×n optical switch matrix density is utilized. Accordingly, n2 matrix elements must be provided in such prior art arrangements. To provide for optical cross-connect functionality requires that a 1×n DWDM de-multiplexer 202 be utilized to de-multiplex n wavelength components from the multiplexed input 201 for coupling to switch matrix 210. A 1×n DWDM de-multiplexer 208 is also necessary to de-multiplex the multiplexed add wavelength components from add input 207 for coupling to switch matrix 210 for the add wavelength input 207. An n×1 DWDM multiplexer 206 is used to multiplex the switched wavelength components from switch matrix 210 to multiplexed output 203. Another n×1 multiplexer 204 is used to multiplex together switched wavelength components from switched matrix 210 to drop output 205. Each switch matrix element 220 of switch 210 may be in either one or the other of two switched states. As shown in FIG. 2, switch element 211 and switch element 213, are activated to drop wavelength components λ1, λn and output the dropped wavelength components to drop output 203. In addition wavelengths λ1, λn received at input 207 are added and outputted at through output 205. All the remaining matrix elements pass wavelength components directly from input de-multiplexer 202 to output de-multiplexer 204. Switch element 211 blocks λ1 from passing from input de-multiplexer 201 to output multiplexer 204, allowing add wavelength component λ1 to traverse path 216 from add de-multiplexer 208 to through multiplexer 204, while rerouting λ1 from input de-multiplexer 202 to drop multiplexer 206 via path 218. Similarly, matrix element 213 allows λn from input de-multiplexer 202 to be routed to drop multiplexer 206 via path 222.

#Although the example shown drops and adds two wavelengths, it will be understood by those skilled in the art, that any number of wavelengths up to number n may be dropped and added.