Optical time- and wavelength-domain paths in future very-high-speed optical communications networks are discussed taking into account trends in current optical transmission and optical signal processing technologies. It is important to investigate optical STM cross-connect systems for time-domain paths in the earlier research phase to ensure the deployment of optical cross-connect technology. The configuration of an optical cross-connect system and the issues that need to be investigated are presented. We also report, for the first time, a preliminary experiment of an optical STM cross-connect system, using 20 Gbit/s optical signals.