Frequency domain propagation, loss, refelcetion

Hi all Comsol friends,

I am calculating the transmitted power loss for one 2-D waveguide, use intop2(emw.nPoav)/intop1(emw.nPoav)

intop2 is the integration of output bounday.
intop1 is the integration of input bounday.

but if the waveguide invloved some refletion, it will of course influences the value of intop1(emw.nPoav), do we have some ways to detected along the wave propagation direction (only +z not -z),

e.g, for a fiber bragg grating, how to use comsol to make propagation smulation about the transmission loss at the Bragg wavelength? how can we neglect the reflection effect to the input facet?

second question is that, in order to kill all the refletion effect at the output bounday interface (scattering bounday only can absorbing the wave perpendicular to the bounday??), can we add PML at the output bounday? just set the output bounday beforethe PML..Is that possible?

Reply from anyone of you are very welcomed! thanks!!!

best regrads,
hualong