Adaptive Coherent Receiver Settings for Optimum Channel Spacing in Gridless Optical Networks

• Main Authors: Ahmad Abdo, Sadok Aouini, Bilal Riaz, Naim Ben-Hamida, Claude D’Amours
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Future Internet
• Subjects: optical communications; networks optimization; coherent communications; phase-locked loop; gridless wavelength selective switch; software-defined networks
• Online Access: https://www.mdpi.com/1999-5903/11/10/206

In this paper, we propose a novel circuit and system to optimize the spacing between optical channels in gridless (also called flexible-grid or elastic) networking. The method will exploit the beginning-of-life link margin by enabling the channel to operate in super-Nyquist dense wavelength division multiplexing mode. We present the work in the context of software-defined networking and high-speed optical flexible-rate transponders. The clock recovery scheme allows the mitigation of jitter by decoupling the contribution of high-jitter noise sources from the clock recovery loop. The method and associated algorithm are experimentally verified where a spectrum gain of up to 2 GHz in spacing between two channels in the Media Channel (MC) is obtained compared to conventional clocking strategies. We showed that the improvement is equivalent to increasing throughput, in a data-center interconnect scenario, by up to 300 giga-bits per second per route.