Patent ID: 9077473
Filing Date: 2015-07-07
Classification: H04J

Abstract:
1. Optical network apparatus comprising: 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 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; 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.