High reflectivity design of the one-dimensional heterostructure photonic crystal in 3 to 5 and 8 to 12 μm infrared regions

The high reflectivity design of the one-dimensional (1-D) heterostructure photonic crystal is investigated in infrared regions 3 to 5 and 8 to 12 μm. First, the reflection characteristics of the light waves in the 1-D periodic photonic crystal are systematically analyzed. Calculations using the transfer matrix method and simulations verify that the λ / 4 dielectric film is the optimum option for achieving the ideal optical reflectivity in a certain wavelength range. The merging of the even-layered high-reflective photonic crystals can be used to expand the gap of the infrared band. In contrast, a combination of the odd-numbered composite photonic crystals can be used to achieve a high transmittance at a wavelength of 10.6 μm with a larger gap in the infrared region. Accordingly, an enhanced photonic crystal is designed using silver metal at the interface and even-numbered dielectric films of Ge and ZnS with 23 layers of the 1-D metal. The simulated reflectivity of this photonic crystal ranges from 95% to 99.9% in wavelength ranges 3 to 5 and 8 to 14 μm. This design significantly reduces the number of layers required for forming a 1-D high-reflective photonic crystal in the infrared bands 3 to 5 and 8 to 12 μm.