In this work we present novel and detailed dispersion the modal analysis of (SOS) strip waveguide in the mid-IR region. The effect of the various design parameters on each mode has been illustrated and carefully studied. The analysis has been extended to cover the fundamental and higher order TE and TM modes over the entire range of operation of this waveguides. The finite element method (FEM) and finite difference method have been both utilized to double verify the analysis. This dispersion analysis has been also utilized to propose novel functional devices in the MIR such as such as mode converter, switches, modulators and TE/TM-pass polarizer design based on the birefringence between the TE and TM mode.