SWITCH FOR OPTICAL SIGNALS

A cross-connect switch for switching optical signals, in particular, Dense Wavelength Division Multiplexed (DWDM) signals is disclosed. The switch includes a switching matrix for each of the predetermined wavelengths of the DWDM signals. The switching matrices include Micro-Electro-Mechanical (MEM) systems which have optically reflective elements, typically mirrors, arranged in rows and columns for switching an incoming optical signal travelling along a row of such elements to an output port aligned with a column of the elements. The switch has input demultiplexers to split an incoming DWDM signal into its component channel wavelengths, each of which is directed to a switching matrix where it is switched to an output port and recombined into an outgoing DWDM signal by a mutliplexer before being transmitted out of the switch. A wavelength-converting switch, connected across the switching matrices, is also included for switching channels between wavelengths. Thus, the switch provides port switching by virtue of the switching matrices and channel switching by virtue of the wavelength--converting switch, as well as a combination of both port and channel switching.