Optical network apparatus for self-seeded communications

An optical add drop multiplexer comprising:

• an optical signal input for receiving an optical input signal comprising at least one wavelength channel;
• an optical signal output for outputting an optical signal for onward transmission;
• a through signal path connected between the optical signal input and the optical signal output for carrying a wavelength channel of the optical signal for onward transmission;
• an add input path connected to the optical signal output for receiving a wavelength channel to be added;
• a drop output path connected to the optical signal input for outputting a wavelength channel to be dropped;
• an optical filter positioned in the add input path for filtering an optical signal received on the add input path from an optical terminal to form a filtered optical signal;
• a reflective device positioned in, or connected to, the add input path arranged to form an optical seed signal by returning at least a portion of the filtered optical signal, the optical seed signal for use in seeding an optical transmitter at the optical terminal, wherein the reflective device is positioned between the optical filter and the optical signal output and wherein the drop output path and the through signal path bypass the reflective device.

A method of processing optical signals at optical network apparatus comprising an optical add drop multiplexer, the optical add drop multiplexer comprising an optical signal input for receiving an optical input signal comprising at least one wavelength channel, an optical signal output for outputting an optical signal for onward transmission and a through signal path connected between the optical signal input and the optical signal output for carrying a wavelength channel of the optical signal for onward transmission, the optical network apparatus further comprising an add input path connected to the optical signal output for receiving a wavelength channel to be added and a drop output path connected to the optical signal input for outputting a wavelength channel to be dropped, the method comprising:

• filtering an optical signal received on the add input path from an optical terminal to form a filtered optical signal;
• forming an optical seed signal using a reflective device positioned in, or connected to, the add input path by returning at least a portion of the filtered optical signal, the optical seed signal for use in seeding an optical transmitter at the optical terminal, wherein the reflective device is positioned between the optical filter and the optical signal output;
• outputting, via the drop output path, a wavelength channel of an optical signal to be dropped;
• passing, via the through signal path, a wavelength channel of the optical signal for onward transmission;
• wherein the outputting, via the drop output path, of the wavelength channel of the optical signal to be dropped and the passing, via the through signal path, of the wavelength channel of the optical signal for onward transmission bypass the reflective device.