By analyzing the ground eigenstates of an InGaAs/InAlAs symmetric coupled quantum well for zero applied electric field and their changes along with an applied electric field, we find its advantages and disadvantages when it is applied to optical switching device. Hence a novel coupled quantum well structure is put forward. To obtain polarization independence, a tensile strain is applied to the quantum well layer. In the case of low applied electric field (F=15 kV/cm) and low absorption loss (for TE mode, α=55.56cm-1; for TM mode, α=75.58cm-1), a polarization-independent large electric-field-induced refractive index change (for TE mode, Δn=0.0108; for TM mode, Δn=0.0107) is obtained in the optimized InGaAs/InAlAs coupled quantum well structure at operating wavelength (λ1550nm). The large refractive index change obtained with the optimized InGaAs/InAlAs coupled quantum well under so low absorption loss and applied electric field is very attractive for the semiconductor optical switch device. This manifests the optimized coupled quantum well structure has a great potential for application to ultra-fast and low-voltage optical switches and traveling wave modulators.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.