Measurement of a compact colorless 3 dB hybrid plasmonic directional coupler.

We fabricated and measured a compact 3 dB hybrid plasmonic directional coupler for silicon photonics integrated circuits with a length of 21.2 μm. The coupler has a 50∶50 coupling ratio over a spectral bandwidth of more than 100 nm around a wavelength of 1.55 μm and has an insertion loss of less than 1 dB.