Nonlinear Impairments
It seems unlikely that these can be dealt with explicitly in a routing algorithm because they lead to constraints that can couple routes together and lead to complex dependencies, e.g. on the order in which specific fiber types are traversed.
A full treatment of the nonlinear constraints would likely require very detailed knowledge of the physical infrastructure, including measured dispersion values for each span, fiber core area and composition, as well as knowledge of subsystem details such as dispersion compensation technology.
This information would need to be combined with knowledge of the current loading of optical signals on the links of interest to determine the level of nonlinear impairment.