A metal-coated etched diffraction demultiplexer with a low polarization dependent loss

The polarization dependent loss (PDL) is analyzed for a metal-coated etched diffraction grating (EDG) demultiplexer based on a method of moment (MoM). Numerical results show that the PDL of a metal-coated type EDG mainly results from the influence of shaded facets, which makes a part of power diffracted to a lower diffraction order. By making the surface of shaded facets with an appropriate roughness, one can improve the PDL of the demultiplexer, effectively.