Pressure Dependent Reflectance and Transmittance Properties in 1D- Photonic Crystal Containing Germanium (Ge)

In this work, we theoretically investigate and study the effect of hydrostatic pressure on the reflectance and transmittance properties of the one-dimensional PC (1D PC) containing germanium (Ge). In the present study, we first take a 1D PC structure composed of alternate layers of germanium (Ge) and air having a finite number of layers. In the second case, we take the same structure by breaking its periodicity such that each part of it acts as the mirror image of each other. The Refractive index of germanium varies under the applied pressure, therefore both reflection bands and transmission modes change with the applied pressure. In order to calculate transmittance and reflectance spectra of the proposed PC, the transfer matrix method (TMM) has been used. It has been observed that by increasing the hydrostatic pressure, the width of the reflection band decreases and the position of reflection bands shifts towards the lower side of wavelength. Further, the transmission modes of the considered PC structure are blue shifted with the increase in applied hydrostatic pressure and show high sensitivity with it. 

Keywords: Defect Mode, Photonic Crystal, Photonic Bandgap Material, Pressure Sensor, Reflectance/Transmittance Spectra, Transfer Matrix Method.