Focus on Time-Dependent Wavelength Drift of DMLs Under Burst-Mode Operation for NG-PON2

Abstract

Upstream time-dependent wavelength drift of Directly Modulated Lasers (DMLs) under burst-mode operation is measured on a Second Next Generation Passive Optical Network (NG-PON2) pre-commercial system. A new measurement method is used to demonstrate that the ITU-T (International Telecommunication Union) recommendations on maximum wavelength drift excursion should be improved. Considering the proximity of the different wavelength channels in the ITU-T grid (down to 50GHz), the time-dependent wavelength drift of directly modulated optical emitters is shown to lead to communication degradation and may cause breakdowns. A way to mitigate this problem is proposed. Index Terms-Adiabatic chirp, direct modulation, heterodyne detection, second next generation passive optical network (NG-PON2), thermal chirp, time-dependent wavelength drift, time and wavelength division multiplexing (TWDM), time division multiplexing (TDM), wavelength division multiplexing (WDM).

Simplified coherent optical network units for very-high-speed passive optical networks

“…Moreover, the DML adiabatic chirp generates an additional non-linear distortion. Additionally, the DML operated in burst-mode suffers from self-heating wavelength drift [30,31], which complicates the frequency tracking and can result in sensitivity penalties due to generating a frequency offset between the transmitter laser and the LO of the coherent receiver [32]. Then, so far, EML and MZM options have been preferred for high-speed PON applications with coherent detection [25,26,[33][34][35][36].…”

Optimization of Hybrid Optical Amplifiers (Raman-EDFA) with a Standard Fiber (SMF) and a maximum pump power of 200mw in access networks: WDM-PON

“…On the other hand, the optimization of the bandwidth in optical fibers, passes by a multiplexing of the traffic of several users [7]. For this purpose, the WDM-PON technology (Wavelength Division Multiplexing in Passive Optical Network) is more often used in the access network, in order to satisfy the unceasingly increasing demand in bandwidth [8,9]. However, this technology can lead to a reduction in inter-channel spacing which can be the cause of intersymbol interference [9].…”

What is the switch for coupling transcription and splicing? RNA Polymerase II C‐terminal domain phosphorylation, phase separation and beyond

“…However, the molecular mechanism by which posttranscriptional splicing occurs, particularly in its spatial context, is not fully understood (Vargas et al, 2011). Importantly, splicing is not only the process coupled with transcription; indeed, capping, RNA editing, and 3 0 end processing occur in a cotranscriptional manner (Bentley, 2014;Martinez-Rucobo et al, 2015;Millevoi & Vagner, 2009;Proudfoot, Furger, & Dye, 2002;Rodriguez, Menet, & Rosbash, 2012), suggesting that cells have mechanisms to select and turn on individual processing machinery at appropriate times. Several mechanisms have been reported to maintain the accuracy of RNA processing.…”