This Thesis has been written as a computational and analytical approach to the study of the optical properties of the Thin Film using Beam propagation Technique in conjunction with Lippmann-Schwinger Equation and its counterpart Dyson's Equation as key Mathematical tools.In keeping with the approach and the idea of the work, the readers are guided through the understanding of the application of the beam propagation method in the study of thin film /nanoscience in general and the efficacy of the use of the above mentioned mathematical tools for such work. "