A polarization rotator assembly for rotating a polarization mode of an electromagnetic signal is provided. The polarization rotator assembly has a waveguiding structure of co-extensive first and second layers defining, successively, an input portion, a subwavelength composite portion and a polarization rotating portion. The subwavelength composite portion is formed by the first and second layers, where the second layer defines a subwavelength pattern. The polarization rotator portion is geometrically configured to rotate the polarization mode of the electromagnetic signal.