Polarization rotator assembly including a subwavelength composite portion

A polarization rotator assembly for rotating a polarization mode of an electromagnetic signal, the polarization rotator assembly comprising:

• a waveguiding structure having co-extensive first and second layers and having a first height corresponding to the first layer and a second height corresponding to a superposition of the first and second layers, the waveguiding structure having a waveguiding axis and comprising successively therealong:
• an input portion formed by the first layer;
• a subwavelength composite portion formed by the first and second layers, where the second layer defines a subwavelength pattern having a characteristic feature size which is less than half an effective wavelength of the electromagnetic signal when propagating therein;
• and
• a polarization rotator portion comprising at least the first and second layers and geometrically configured to rotate a polarization mode of the electromagnetic signal.