An access topology that brings one wavelength to each customer.
That's in contrast to a typical Passive Optical Network (PON), in which each wavelength is split among a group of customers -- up to 16 or 32, in most architectures. Having a wavelength of one's own means more bandwidth, potentially, so
WDM-PON is often characterized as a way to achieve speeds of 1 Gbit/s or more to the home.
The problem is that it's expensive, because the technology is still in an early phase of commercialization.