2×2 adiabatic 3-dB coupler on silicon-on-insulator rib waveguides

We demonstrated 2×2 broadband adiabatic 3-dB couplers based on silicon rib waveguides. Functioning as 50/50 optical power splitters, these devices can be used in optoelectronic applications. Fabricated using siliconon-insulator technology, we demonstrated the performance of the adiabatic 3-dB couplers by integrating two couplers into an unbalanced Mach-Zehnder Interferometer (MZI). Measurements of the MZI were made over a 100 nm wavelength range. Extinction ratios in excess of 33.4 dB were obtained over the wavelength range from 1520 nm to 1600 nm, for light injected into Input Port1 and measured at Output Port2, i.e., the cross port response.