OPTICAL NETWORK WITH WAVELENGTH-DEPENDENT ROUTING

PCT No. PCT/GB95/02214 Sec. 371 Date May 7, 1997 Sec. 102(e) Date May 7, 1997 PCT Filed Sep. 19, 1995 PCT Pub. No. WO96/09736 PCT Pub. Date Mar. 28, 1996An optical network in which data signals are encoded with a wavelength corresponding to the address of the signals includes at least one point therein, a data routing switch (1) which comprises: a wavelength comparator (3) for example a Brag grating or a notch filter that will receive data signals and has associated therewith a characteristic wavelength so that it will send the data signal along a gate enabling line (5) or not in accordance with the relationship between the data signals encoding wavelength and the characteristic wavelength of the comparator, and a gate (7) which transmits or blocks the data signal in response to the presence or absence of the data signal in the gate enabling line and a number of data routing switches having different characteristic wavelengths so that routing of the data is determined by which switch characteristic wavelength matches the data encoding wavelength. Since the wavelength comparison is a passive process, comparison and switching can be performed more rapidly than with conventional systems.