Error-free all-optical add-drop multiplexing using HNLF in a NOLM at 160 Gbit/s - Electronics Letters

Introduction: An add-drop multiplexer (ADM) is one of the key elements in optical time division multiplexed (OTDM) networks. Various methods of performing OTDM add-drop have been demonstrated. Recently add-drop operation at 16 10 Gbit=s has been demonstrated with the use of a gain transparent ultrafast nonlinear interferometer (GT-UNI) [1] switch and at 4 40 Gbit=s with travelling-wave electroabsorption modulators (TW-EAMs) using an electrical clock input signal [2]. This Letter presents an all-optical add-drop multiplexing method at 4 40 Gbit=s using a commercially available highly-nonlinear fibre (HNLF). The advantage of using HNLF as a nonlinear switching medium is the possibility of realising high speed operation (up to 640 Gbit=s) owing to the ultrafast fibre response time. The advantage of HNLF over conventional dispersion shifted fibre (DSF) is that the length can be significantly shorter and less switching power is required, which in general leads to more robust switching. Several demultiplex experiments with HNLFs have been reported [3, 4]; however simultaneous add=drop operation with HNLFs has not been reported so far.