New types of 2 x 2 wavelength-switching blocks for optical cross-connects

Two types of modular 2/spl times/2 wavelength-switching blocks are proposed in this letter. A 2/spl times/2 fixed wavelength-switching block can cross-connect two fixed channels between two fibers, and a 2/spl times/2 tunable wavelength-switching block can cross-connect any two channels between two fibers. These modular blocks can be used to build scalable multiwavelength cross-connects in optical networks.