The overall transmitted efficiency at 1550 nm for Nylon-Teflon/Teflon-Nylon (N-T/T-N) grating Siliconon-insulator (SOI) structure with defect in even and odd position was investigated in this paper. Different types of losses, such as absorption, reflection and diffraction, were considered to find out the overall transmitted efficiency. The absorption loss of both Nylon-Teflon (N-T) and Teflon-Nylon (T-N) structure is zero at the wavelength of 1550 nm. Reflectance of these structures was analyzed by using plane wave expansion (PWE) method. Simulation result showed that reflectance as well as transmittance was varied linearly with respect to defect at odd and even positions. Simulation is also done for the diffraction efficiency at 1550 nm with respect to detuning from Bragg’s angle, which was ranged from - 0.4 rad to + 0.4 rad. Finally, it was found that overall transmitted efficiency increased as even defect position varied from 2nd to 10th for both N-T/T-N grating SOI structure. Similarly, the overall transmitted efficiency decreased as odd defect position changed from 3rd to 11th for both N-T/T-N grating SOI structure.