Optical Investigations of Nanophotonic LiNbO₃ Films Deposited by Pulsed Laser Deposition Method

Abstract

The nanocrystalline structure of Lithium niobate (LiNbO3) was prepared and deposited onto substrate made of quartz by utilize pulse laser deposition technique. The effect of substrate temperature on the structural, optical and morphological properties of lithium niobate photonic film grown was studied. The chemical mixture was prepared by mixing the raw material (Li2CO3, Nb2O5) with Ethanol liquid without any further purification, at time of stirrer 3hrs but without heating, then annealing process the formed material at 1000C° for 4hrs. We characterized and analyzed the LiNbO3 nanostructure thin films by utilize Ultra-Violet Visible (UV-vis). The UV-vis measurements show that, when the substrate temperature increases, the values of transmission, absorption and energy band gap will decreased, but the values of reflection and refractive index will increased. That means the LiNbO3 thin film prepared at substrate temperatures 300C° give the best result for manufacture the optical waveguide.

Highly Stable Colloidal Lithium Niobate Nanocrystals with Strong Violet and Blue Emission

“…The optical band gap energy ( ) of the direct allowed transitions was also characterized from this figure when the linear portion of the curve was extrapolated to a value of zero. The calculated value of the energy band gap ( ) for LiNbO 3 was equal to 4.25 eV, which was in good agreement with other published letters. , The Tauc plot for the indirect band gap is presented in Figure c to complete the analysis. The variation of (αh v ) 0.5 versus photon energy ( hv ) for colloidal nanocrystalline LiNbO 3 is plotted in this figure.…”

“…Furthermore, an absorption edge at 4.25 eV was observed in the absorption spectrum of the colloidal LN nanoparticles. Consequently, a blue shift of 0.55 eV in energy relative to that of the bulk LN (Eg = 3.7 eV and λ = 335 nm at 300 K) was observed, which is due to the effect of quantum size, as expected from the nanoscale nature of the colloidal LN nanostructure . In other words, when we solve the Schrodinger equation in well agreement with the infinite wall and boundary conditions, we find that the electrons will have only discrete energy levels in the conduction band and so do the holes in the valence band.…”

“…Consequently, a blue shift of 0.55 eV in energy relative to that of the bulk LN (Eg = 3.7 eV and λ = 335 nm at 300 K) was observed, which is due to the effect of quantum size, as expected from the nanoscale nature of the colloidal LN nanostructure. 29 In other words, when we solve the Schrodinger equation in well agreement with the infinite wall and boundary conditions, we find that the electrons will have only discrete energy levels in the conduction band and so do the holes in the valence band. As the particle size decreases, the overlapping of orbitals of atoms decreases, and this leads to the formation of narrow valence and conduction bands.…”

“…LiNbO 3 was equal to 4.25 eV, which was in good agreement with other published letters. 29,31 The Tauc plot for the indirect band gap is presented in Figure 2c to complete the analysis. The variation of (αhv) 0.5 versus photon energy (hv) for colloidal nanocrystalline LiNbO 3 is plotted in this figure.…”

Omni‐functional crystal: Advanced methods to characterize the composition and homogeneity of lithium niobate melts and crystals

“…[96] There are many methods for measuring the refractive index of LN crystals, including the prism coupler method [97][98][99] and the minimum angle of deviation method; [100] an UVvis spectrophotometer can also be used to measure the absorption spectrum and thereafter calculate the refractive index. [97,101] The minimum angle of deviation method requires the sample to be processed into a prism, which is unsuitable for measuring the refractive index of optical devices. The more commonly used UV-vis absorption spectroscopy and prism-coupling methods place fewer requirements upon sample processing and are more convenient for testing.…”