Mode conversion in a thin-film corrugated waveguide

Efficient mode conversion (~70–90%) was achieved and investigated in a multimode thin-film corrugated waveguide. The corrugations were nonsinusoidal so that modes could be converted using different orders of the spatial harmonics of the corrugation grating, tuning only slightly the grating in respect of the angle. The dependences of the mode conversion efficiency on the length of the grating were determined. The experimental results were compared with the theory.