A method of writing a pattern, such as a waveguide, in a bulk glass substrate. The network elements are allocated unique local addresses only within the network. The servo writing apparatus uses the servo pattern written on the disk by a write head device to successively add the servo pattern into the whole surface on the disk. 5 and synthetic single crystal diamond which may be obtained by the method recited are also described. Thus, in the presence of a reception interference, the interference-detecting signal of the interference detector actuates the logic switching device to another switching position, and wherein the phase-controller serves as a low-pass filter for limiting the speed of the phase control.