10 dB reduction of drop operations of DSP-enabled soft-ROADMs for coherent systems

• Published in: Optics communications Vol. 421; pp. 105 - 109
• Main Authors: Jin, W., Zhang, X.L., Duan, X., Dong, Y.X., Giddings, R.P., Qiu, K., Zhang, C.F., Tang, J.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.08.2018
• Subjects: Coherent systems; Digital filtering; Digital signal processing (DSP); Reconfigurable optical add/drop multiplexer (ROADM); Digital filtering; Digital signal processing (DSP); Reconfigurable optical add/drop multiplexer (ROADM); Coherent systems
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2018.04.004

Newly proposed DSP-enabled ROADMs free from O−E−O conversions offer an excellent opportunity of utilising advanced DSP techniques to greatly simplify complicated conventional ROADM configurations, to introduce more highly desired networking functionalities and to create a programmable environment capable of addressing elastic 5G slicing and supporting the SDN paradigm. In this paper, detailed analytical and numerical investigations are performed, for the first time, of DSP-enabled ROADM drop operation performances in coherent systems. Two simple but effective drop operation approaches are proposed analytically and validated numerically, which, compared to the previously published quadrature-point-biased Mach–Zehnder modulator-based ROADM drop element subject to a standard drop RF signal, can not only improve the minimum required OSNR requirements by approximately 10 dB, but also considerably enhance the drop operation performance robustness to modulation index variations.