A novel InGaAs/InAlAs coupled quantum well structure is proposed for large field-induced refractive index change with low absorption loss. In the case of low applied electric field of 15 kV/cm and low absorption loss ('alpha' <= 100 cm^(-1)), a large field-induced refractive index change (for transverse electric (TE) mode, 'Delta' n = 0.012; for transverse magnetic (TM) mode, 'Delta' n = 0.0126) is obtained in the structure at the operation wavelength of 1.55 um. The value is larger by over one order of magnitude than that in a rectangular quantum well. The result is very attractive for semiconductor optical switching devices.