A CMOS compatible three-port all-optical silicon switch working in 1.473 to 1.502  μm (extinction ratio   (  ER  )    =  5.5  dB, λ_C  =  1.488  μm) and 1.512 to 1.5306  μm (ER  =  3.079  dB, λ_C  =  1.52  μm) bands is demonstrated in this work through numerical simulations. However, in spite of the all optical control, having null refractive index contrast between the transmitting and control waveguides of the switch causes the switching merit to deteriorate because of light leaking from the transmitting waveguide. Later, by employing Franz–Keldysh effect-induced absorption coefficient tuning of Si_{1  −  x} Ge_x (x  =  0.85) to replace the silicon control port of the switch, 2.95-dB leakage reduction in the ON state is achieved, which is assessed in detail. Also, our numerical simulations confirmed the bandwidth of 38 GHz, which suggested a multilayer plasmonic waveguide structure.