High Power Waveguide Polarizer with Broad Bandwidth and Low Loss

Embodiments of the invention provide high power waveguide polarizers with broad bandwidth and low loss, and methods of making and using the same. Under one aspect of the present invention, a waveguide polarizer includes a hollow waveguide body having an interior surface; a first ridge disposed on the interior surface of the hollow waveguide body and having an inward-facing surface; and a first plurality of projections disposed on the inward-facing surface of the first ridge. The projections may have a width that is narrower than that of the ridge, and a length that is tunable. The length of the projections may be selected to induce about a 90-degree phase delay in a first mode propagating in a plane parallel to the first ridge relative to a second mode propagating in a plane perpendicular to the first ridge.