FIRST-PRINCIPLES INVESTIGATION OF ELECTRONIC AND NONLINEAR OPTICAL PROPERTIES OF LINBO3 FOR HIGH-SPEED FIBER-OPTIC COMMUNICATION APPLICATIONS

First-principles DFT calculations were used to study the electronic and optical properties of LiNbO3. The bandstructure shows a clear wide band gap with no states at the Fermi level, confirming its insulating nature. Thevalence bands are dominated by localized O-2p states, while the dispersive Nb-4d conduction bands enableefficient optical excitations. The total density of states supports these features, with prominent peaks linked toflat bands. Optical properties derived from the dielectric function reveal a high refractive index (3.37) near theabsorption edge, indicating strong polarization and light–matter interaction. Low absorption in the visible regionconfirms optical transparency, whereas intense ultraviolet absorption and conductivity peaks arise frominterband transitions. The energy loss function exhibits a strong plasmon resonance around 25–26 eV, reflectingcollective electronic excitations. Overall, the results highlight the excellent optical stability and strong electronicresponse of LiNbO3, making it highly suitable for nonlinear optics, electro-optic modulation, and fiber-opticcommunication applications.