Optical wavelength-division-multiplexed cross-connect incorporating optically controlled optical switch

#This invention relates generally to nonlinear semiconductor optical devices. More particularly, it relates to an ultrafast optically controlled optical switch and crossbar architecture for use in wavelength-division-multiplexed systems.

#Communications systems are increasingly using optical fiber as the transmission medium, because of its low loss, immunity to interference, and extremely large bandwidth. In wavelength-division-multiplexed (WDM) systems, multiple wavelengths are used to allow many communication channels on a single optical fiber, allowing for much greater information transmission and network capacity. Modulated light beams are mixed into the fiber using optical couplers, and demultiplexed at the receiver end by optical filters. It is often necessary to transfer signals between optical networks operating at different wavelengths, and therefore transfer a particular optical signal from one channel to another. Switching information between channels requires the ability to change a particular signal of information from one wavelength to another. Switching of this manner requires both a device that can convert signal wavelengths and a system architecture, incorporating the device, that can be scaled to required capacities.

#A WDM optical system is disclosed in U.S. Pat. No. 5,504,609, issued to Alexander et al. This system includes complex remodulators for transferring a signal from an input wavelength to an output wavelength. Each remodulator contains a photodiode or similar means for converting an optical input signal to an electrical signal, which is then amplified, filtered, and amplified again. The resultant electrical signal is used to modulate an optical source by exploiting the electro-optical effect in a waveguiding medium to create an amplitude-modulated output signal. The combination of electronic and optical elements required in the system of Alexander et al. greatly limit the net throughput in the system, and do not effectively take advantage of the increased bandwidth provided by the optical fiber. The remodulators also dissipate large amounts of power and make large arrays of switches impractical.

#FIG. 1 is a schematic diagram of a wavelength-division multiplexed system incorporating an optical cross-connect of the present invention.

#FIG. 2 is a front plan view of an optical cross-connect illustrating the wiring of electrical control signals.

#FIG. 3 is a schematic diagram of a wavelength-division multiplexed system incorporating a preferred embodiment of an optical cross-connect of the present invention.

#Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following preferred embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

#FIG. 1 illustrates a particular embodiment of an optical crossbar architecture of the present invention, an optical cross-connect 10 containing a matrix of optically controlled optical switches 12. Switches 12 are located at the cross points of optical cross-connect 10. Each switch 12 is capable of transferring a signal from one channel (i.e. wavelength) to another. Optical cross-connect 10 is further enabled by an electrical control function that sets whether a particular optically controlled optical switch 12 is activated for use or not.

#In FIG. 1, three optical input signals 14, 16, and 18 are shown, each of which may have a different signal wavelength. Specifically, these wavelengths are λ1, λ2, and λ3. Each input signal is spread by optics over a horizontal row of cross-connect 10. For example, optical input signal 14 is spread over horizontal row 20. There are also three optical power light beams 22, 24, and 26, each of which may have a different wavelength. Specifically, these wavelengths are λ4, λ5, and λ6. A given optical power beam is spread by optics over a vertical column of cross-connect 10. For example, optical power beam 26 is spread over column 28. Optics are also arranged so that any light passing through a given vertical column of cross-connect 10 is collected into a single optical output signal 30, 32, or 34.