NG-PON2 is a unique departure from the evolution of single channel TDM-PON systems in that rather than increasing service data rates by incrementally increasing symbol rates, NG-PON2 blended TDM-PON with WDM-PON to create a new optical media access technology, TWDM-PON or Time and Wavelength Division Multiplexed PON. TWDM-PON introduced the first standardized use of DWDM channels that must be operated in burst mode and as such introduced new optical challenges. How these challenges were met, and the lessons learned along the way will be described below.