Optical network apparatus comprises an optical add drop multiplexer (10) comprising an optical signal input (11) and an optical signal output (12). An add input path (15) is connected to the optical signal output (12) for receiving a wavelength channel to be added. A drop output path (16) is connected to the optical signal input (11) for outputting a wavelength channel to be dropped. A through signal path (18) is connected between the optical signal input (11) and the optical signal output (12). An optical filter (20) is positioned in the add input path (15) for filtering an optical signal received on the add input path (15) from an optical terminal (40). A reflective device (30) in the add input path (15) is arranged to form an optical seed signal by returning at least a portion of the filtered optical signal. The optical seed signal is for use in seeding an optical transmitter at the optical terminal (40). The reflective device (30) is positioned between the optical filter (20) and the optical signal output (12). The drop output path (16) and the through signal path (18) bypass the reflective device (30).