Experimental characterization of an ultra-broadband dual-mode symmetric Y–junction based on metamaterial waveguides

•Detailed experimental study that demonstrates the broadband performance and relaxed fabrication tolerances of an SWG-based Y–junction.•Fundamental transverse-electric (TE0) mode excess loss per splitter measured through linear regression of the response of cascaded SWG and conventional Y–junctions.•Excess losses for the first-order transverse-electric (TE1) mode measured using a mode multiplexer, potentially enabling new applications of the proposed device.•Excess losses below 0.3 dB for TE0 within 260 nm (1420–1680 nm) and below 1 dB within a 100 nm bandwidth (1475–1575 nm) for TE1.