Suppression of free carrier absorption in silicon using multislot SiO2/nc-Si waveguides

Free carrier absorption (FCA) in silicon is the major obstacle toward achieving optical gain in Si nanostructure systems. In this Letter, we present experimental results of pump-induced loss for TE and TM polarization in multislot SiO2/nc-Si waveguides. Continuous wavelength and ultrafast studies of carriers excited in the nc-Si multilayers reveal strong suppression of transmission loss related to FCA in Si nanostructures for TM-polarized probe light. We demonstrate theoretically and experimentally that FCA may be reduced under TM polarization as much as 9 times compared to TE polarization.