The SCTE has approved SCTE 233 2016, "Wavelength-Division Multiplex Small Form Factor Pluggable (PXFP-WDM) Optical Transmitter Module Interface Specification." The standard defines optics for use in PON OLTs. The use of a PON extender architecture utilizing WDM optics enables multiple 10G PON links to be deployed on different wavelengths over a single fiber at distances much greater than 20 km. WDM pluggable optics compatible with PON OLT line cards enable a multi-wavelength link between the OLT platform and a PON repeater.
The standard is available at http://www.scte.org/SCTE/Standards/Download/SCTE/Standards/Download_SCTE_Standards.aspx.