Multilayer Optical Waveguides as Isolators, Polarizers and Other Optical Devices: A Review

An optical waveguide is a structure guiding the wave of light, limiting it to travel through the given and specific path. If the size of transverse dimensions is bigger than the guided light wavelength, then total internal reflection (TIR) and geometrical optics can be used to explain the working principle of geometrical optics. There is a strong control from Photonic Band Gap (PBG) structures over light and some of the best use cases of such structures rely on the functionalities while using defects in lattice which had led to the Photonic Crystal (PhC) heterostructure design. The photonic band structure is influenced by the defects in the PhC and it can cause the confinement or flow of light apart from specific pathways in the property and crystal of those structures.

In this paper, we have investigated the application areas of polarizers, isolators and other optical devices in optical waveguides. The loss occurred in the added layer and changes in the properties of the waveguide is also discussed. It is also observed that resonant layer effect (RLE) can improve and play a pivotal role to develop a lot of devices like polarizers, modulators, and isolators.