Self-imaging confirmed in plasmonic channel waveguides at visible wavelengths

Abstract

We experimentally confirm self-imaging induced by multi-mode interference of plasmon polaritons in a channel waveguide at visible wavelengths. A designed plasmonic channel waveguide, fabricated as three structural segments at two different channel depths, operates as a single- and multi-mode waveguide. Illuminated by incident light of wavelength 635 nm, the channel plasmon polaritons propagate towards the output port if the length of the multi-mode waveguide is equivalent to twice the beat length for multi-mode interference. If the length of the multi-mode waveguide is equivalent to the beat length, only a few of these plasmon polaritons propagate to the output port as most of them are reflected at the far end of the multi-mode segment of the waveguide. Experimental results enable a clear characterization of self-imaging induced by the multi-mode interference of channel plasmon polaritons.