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

Upstream time-dependent wavelength drift of directly modulated lasers under burst-mode operation is measured on a second next generation passive optical network precommercial system. A new measurement method is used to demonstrate that the international telecommunication union (ITU-T) recommendations on maximum wavelength drift excursion should be improved. Considering the proximity of the different wavelength channels in the ITU-T grid (down to 50 GHz), 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.