<formula formulatype="inline"><tex Notation="TeX">$C$</tex> </formula>-Band Optical 90<formula formulatype="inline"><tex Notation="TeX">$^{\circ}$</tex> </formula> Hybrids in Silicon Nanowaveguide Technology

@article{Voigt2011formulaFN,
  title={<formula formulatype="inline"><tex Notation="TeX">\$C\$</tex> </formula>-Band Optical 90<formula formulatype="inline"><tex Notation="TeX">\$^\{\circ\}\$</tex> </formula> Hybrids in Silicon Nanowaveguide Technology},
  author={Karsten Voigt and Lars Zimmermann and G. Winzer and Hui Tian and Bernd Tillack and Klaus Petermann},
  journal={IEEE Photonics Technology Letters},
  year={2011},
  volume={23},
  pages={1769-1771}
}
We present a fully passive silicon nanowire-based optical 90° hybrid based on a 4 × 4 multimode interference (MMI) coupler for application in coherent receivers. Simulations show 4×4 MMI coupler performance regarding excess loss, imbalance, bandwidth, and phase accuracy. The 4×4 MMI couplers show stable performance over C-band with excess loss and imbalance<; 0.5 dB and phase accuracy better than 5°. We obtain over C-band minimum extinction ratios of 20 dB.