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A ternary photonic crystal structure is considered, whose unit cell is made of Ge, Si and polymer (cellulose acetate). The transmittance characteristics for the proposed TPC are plotted in the THz region, by employing the transfer matrix method, with variations in incident angle and layer thicknesses (in microns). When we vary the incident angle, it is found that the single bandgap obtained at higher frequency is almost independent of the incident angle and such property may be useful in designing sensors and omnidirectional reflectors (ODRs). Thereafter, on increasing the thickness of the polymer layer at normal incidence, we find that the obtained single bandgap is shifted towards lower frequency side and becomes wider. If we increase the Ge layer thickness at normal incidence, the PBG becomes narrow and is shifted towards lower frequency side and after the layer thickness above 6 μ m, there occur two bands, which show multiband filter characteristics. Further, on increasing the Si layer thickness, the band show similar behavior, while these band gaps are more narrow and the first band disappears above the layer thickness of 6 μ m. Thus, the novel results show the applications of such ternary PC in designing ODRs, filters, sensing devices, and space communication. [ABSTRACT FROM AUTHOR]

By employing the well-known transfer matrix method, we plot the transmittance spectra of a 1D symmetrical defective binary PC made of Ge and SiO2 in the form of (AB)N/2D(BA)N/2 with RHP based MCP as a defect. Here, we analyze the position and corresponding transmission of the defect mode lying in the wide PBG, with variations in defect and two layers of the binary structure, respectively. With increase in the defect thickness, the defect mode position is tuned towards a low frequency and the defect mode transmission increases from defect thickness of 8 to 12 mm. With increase in the SiO2 thickness, the defect mode is shifted towards low frequency side and corresponding transmission of the defect mode decreases. Defect mode is not observed for Ge thickness up to 2 mm, if we increase its thickness above 2 mm, the width of first wide gap decreases, and it is shifted towards a low frequency. On increasing the Ge thickness, the defect mode position is shifted towards lower frequency and transmission corresponding to defect mode increases. These novel results based on variations in both defect mode frequency and transmission, by changing the thicknesses of layers and defect width, can be employed in designing tunable reflectors and optical sensors. [ABSTRACT FROM AUTHOR]