METHOD OF CONTROLLING THE TRANSMISSION CHARACTERISTICS OF AN OPTICAL COMMUNICATIONS NETWORK

摘要

An optical communications system includes a central station (2) coupled to a plurality of outstations (Oi) by an optical waveguide network (4) which can transmit optical signals to the outstations on a plurality of wavelengths ( lambda 1 to n). There is included a refractive grating (6) formed within an optical waveguide of the network (4) immediately before the outstation O1 which is reflective to optical signals of a wavelength ( lambda i) that propagate as a single mode in the network (4). The grating (6) permits optical signals of wavelengths greater and smaller than lambda i to pass so selectively blocking an optical wavelength channel from the outstation O1.