FDTD Modelling of 1D Photonic Crystal for Thermal Masking Application with CPML Absorbing Boundary Condition

摘要

Periodic structures of double positive and double negative metamaterial of thickness of lambda/ 4 is designed to stop long-wave infrared and mid-wave infrared frequencies for masking from infrared detection devices. Band-gaps are obtained by calculating reflection and transmission coefficients at probe point close to the front and back faces of the periodic structure. 1D-finite difference time domain method is implemented in Matlab to study the electromagnetic wave propagation which is incident normal to a periodic stack of double positive and double negative metamaterial of having refractive indices of 9 and -6 respectively, at centre wavelength. Drude model is adapted to model double negative medium. Band-gap obtained are compared with the conventional photonic crystal by replacing the double negative medium with a double positive medium with the magnitude of refractive index same as that of double negative medium. Band-gap obtained confirms the presence of Zero-n. band-gap in DPS-DNG photonic crystal which is wider than the reflection band in conventional photonic crystal; nearly twice in mid-wave infrared region and five times in long-wave infrared region. A novel and highly efficient convolutional perfectly matched layer absorbing boundary condition is used to terminate the infinite computational finite difference time domain lattices.