One-Dimensional Four-Layered Photonic Heterostructures: Analysis of Transmittance

The transmittance characteristics and the band structure of photonic heterostructures consisting of four distinct dielectric materials are analyzed using the transfer matrix method. An enhanced band structure of such crystals is discovered. It is shown that the band structure is strongly influenced by the arrangement of unit cells in the periodic building blocks of the crystals. The transmission spectra are evaluated for varying layer thicknesses and incident angles to investigate their impact on wave propagation. The symmetrical results for periodicities, sub-layer thickness, and oblique incident angles indicate robust bandgaps with blue shifting and enhanced transmission. Moreover, the periodicity in different cases, followed by the period, has also shown to have a great impact on the emergence of multiple bandgaps. The photonic bandgap and frequency are associated with the lattice elements of the unit cell, shifting naturally as a fundamental property of the structure, which has been achieved by the alteration of unit cells. Hence, the proposed photonic heterostructures offer significant potential for developing efficient band-stop and band-pass filters, facilitating their use in multi-functional integrated optical circuits within the Terahertz spectrum.