ABSTRACT
In this paper, a stackable band pass filter is proposed and reported with supporting numerical results. The numerical simulation is an application of the method of characteristics in one dimension which yields the computational solutions of Maxwell's equations and validates that the proposed structure enhances the transmission (minimizes the reflection) a specific spectral band. The proposed unit structure consists of five layers of transparent thin sheets that are made of three different dielectric materials each of which has a particular thickness and is symmetric in formation and stackable for broader bandwidth if necessary. These transparent dielectric materials (εra, εrb, εrc) are assumed uniform, non-magnetic, and lossless. When a ray of light moves from εra through εrb to εrc and since the strength of the reflection depends on the dielectric constant of the three media, the maximum total transmittance requires the following: εra < εrb < εrc and https://www.w3.org/1998/Math/MathML"> ε r b = ε r a ε r c https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003460763/a1dd00af-5f0d-42a5-a080-674b9e863cf3/content/inline-math1_1.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> which is known as the Rayleigh's film. The proposed unit structure is εra-εrb-εrc-εrb-εra where each dielectric material is equivalent to 90° in optical path length. The spectral band of interest is assuming visible light whose wavelengths range from 400 nm (750 THz) to 550 nm (545.5 THz). The numerical results strongly support the proposed stackable band pass filter.
