2x2 Adiabatic 3-dB Coupler on Silicon-on-Insulator Rib Waveguides

We demonstrated 2x2 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 silicon-on-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 Port 1 and measured at Output Port2, i.e., the cross port response.