Efectos del acoplamiento intramolecular en el estudio de las respuestas ópticas no lineales en colorantes orgánicos en la señal de Mezcla de Cuatro Ondas

Abstract

In this work, the effects of the vibronic coupling on nonlinear optical properties (absorption coefficient and refractive index) of organic dyes (Malachite Green and Cyanine dyes) immersed in a thermal reservoir is evaluated by the Four-Wave Mixing scheme. The optical properties were defined as a function of the third-order nonlinear optical susceptibility, which is determined by the induced polarization. The induced polarization is calculated using the conventional optical Bloch equations, which were derived from the Liouville equation using the matrix density formalism for molecular systems interacting with electromagnetic fields through electric dipole interaction. Both the permanent and transition dipole moments were derived from the Born-Oppenheimer approximation and the Herzberg-Teller approximation. The organic dyes were modeled as two-level quantum systems with vibrational states. Thereby, it was demonstrated that the vibronic coupling decreases the theoretical value of the nonlinear optical properties absorption coefficient and refractive index of molecular systems.