International Journal of Physics | Vol. 2, No. 6, June 2011 | pp. 43–51
DOI: 10.46882/2011/IJP/000018
Article Type: Original Research Paper
Title: Theoretical Exploration of Non-Linear Optical Properties in Organic Dye Derivatives Using Density Functional Theory
Names of Authors: Y. A. Bello¹, H. M. Al-Qahtani²
Authors’ Affiliations: ¹Department of Physics, University of Ilorin, Ilorin, Nigeria; ²Department of Physics, King Saud University, Riyadh, Saudi Arabia
Abstract: Organic molecules featuring strong donor-acceptor configurations exhibit large non-linear optical (NLO) responses, making them ideal for high-speed electro-optic modulators and optical switches. This paper provides a theoretical investigation into the electronic configurations, frontier molecular orbital gap, and non-linear optical parameters of a series of novel azobenzene dye derivatives. The quantum chemical computations were executed using density functional theory (DFT) at the B3LYP/6-311G(d,p) level. The electric dipole moment, molecular polarizability, and first-order hyperpolarizability (beta) were computed for each derivative. Our results indicate that introducing strong electron-withdrawing nitro (-NO₂) and cyano (-CN) groups at the para-position narrows the HOMO-LUMO energy gap from 3.42 eV to 2.15 eV. This modification accelerates internal charge transfer across the conjugated pi-linker system. Consequently, the calculated first-order hyperpolarizability of the nitro-substituted derivative reached 4.5 x 10⁻³⁰ esu, which is approximately 25 times larger than that of standard urea references. The frequency-dependent NLO responses were also modeled, highlighting strong dispersion effects near resonance frequencies. These quantitative variations indicate that optimizing substituent electron affinities can enhance the efficiency of organic non-linear optical devices.
Keywords: Non-linear optics; Density functional theory; Azobenzene dyes; Hyperpolarizability; HOMO-LUMO gap; Charge transfer; Quantum chemical calculation; Electro-optic modulator.
Manuscript Timeline: Received: March 20, 2011; Revised: April 28, 2011; Accepted: May 20, 2011; Published: June 15, 2011.
Citation: Bello, Y. A., & Al-Qahtani, H. M. (2011). Theoretical Exploration of Non-Linear Optical Properties in Organic Dye Derivatives Using Density Functional Theory. International Journal of Physics, 2(6), 43–51.
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