C. TeekaS. PipatsartP.P. Yupapin2025-03-102025-03-102012Microwave and Optical Technology Letters1098276010.1002/mop.271232-s2.0-84865525569https://repository.dusit.ac.th//handle/123456789/5006We present the general formulation of light reflection using a series of one-dimensional (1D) photonic crystals (PCs) with different periods, which is made of nonabsorptive materials of any refractive indices.To have a large bandgap, the spectral range of reflection, the periods of 1D PCs must be distributed in a geometrical progression with a common ratio, r, smaller than a maximum value of r c. In this letter, the exact expressions for rc, the bandgap to mid gap ratio of the PC heterostructure and the minimum number of PCs to achieve the desired range of bandgap in single and all angles of incidence have been presented. The proposed method can be used to design the optical filters for vast range of applications such as ultraviolet (UV) filters (i.e., sunglasses, eye safety glasses, UV photography filters) and visible light filters. © 2012 Wiley Periodicals, Inc.Bragg reflectorsmultilayer filtersone-dimensional photonic crystalsArticleScopus