Study of thermo-optic and thermo-polarizability coefficients of ions in congruent LiNbO3 open-type optical waveguide using point dipole approximation

• Published in: Indian journal of physics 2024-09, Vol.98 (10), p.3681-3688
• Main Authors: Suhasini, Velagapudi, Subbareddy, I. V., Manoher, Pasunooti
• Format: Article
• Language: English
• Subjects: Approximation; Astrophysics and Astroparticles; Dipoles; Lithium niobates; Optical waveguides; Original Paper; Physics; Physics and Astronomy; Refractivity; Temperature
• ISSN: 0973-1458; 0974-9845
• DOI: 10.1007/s12648-024-03072-z

The thermo-optic coefficients (TOCs), thermo-polarization coefficients (TPCs) and dn/dT, d α /d T of congruent lithium niobate LiNbO 3 / LN (mole ratio Li/Nb = 0.946) are tested within the temperature range of 293–773 K at λ  = 0.4358 µm, λ  = 0.6328 µm and λ  = 1.15232 µm employing the point dipole approximation. The refractive indices, n o and n e , were first determined at these temperatures and wavelength ranges, by iterating the electronic polarizabilities of Nb 5+ and O 2+ ions. It has been found that the polarizability of Nb 5+ ions drops and that of O 2− ions increases when temperature rises for a particular wavelength. Both Nb 5+ and O 2− lose polarizability with increasing wavelength for a given temperature. TOCs for n o and n e rise as the temperature rises. The TOC rises as wavelength for n o and n e decreases. TPCs of O 2− rise in ions and temperature causes Nb 5+ ions to decrease. At a particular temperature, TPCs of O 2− ions become less while Nb 5+ ions grow as wavelengths rise. Generally, it is used in potential electronic polarizabilities and thermal refraction applications.