Abstract
The two-photon absorption and optical limiting properties of two dibenzylideneacetone derivatives with different substituent positions have been theoretically investigated by solving the coupled rate equations-field intensity equation in the nanosecond time domain using an iterative predictor-corrector finite-difference time-domain method. The calculations show that the electronic structure, the transition dipole moment, the energy gap between the highest occupied orbital (HOMO) and the lowest unoccupied orbital (LUMO), and the pumping rate for the two molecules are quite different due to the different position of chlorine atoms. Importantly, two-photon absorption and optical limiting properties of the molecules depend crucially on the substituent positions of the terminal group, indicating that subtle manipulation on the molecule can affect the nonlinear optical properties of the medium.
Highlights
Materials with excellent two-photon absorption (TPA) properties have attracted a tremendous amount of interest due to their versatile applications in frequency up-conversion lasing [1,2,3], 3-D microfabrication [4], two-photon fluorescence imaging [5], two-photon photodynamic therapy [6,7], and especially optical limiting (OL) [8,9,10]
Where Γsn represents the decay rates of the Sn state, respectively. γS0 S1 and γS1 S2 denote the rates of the one photon induced transitions S0 →S1 and S1 →S2, which can be given by the one-photon absorption (OPA) cross sections σS0 S1 and σS1 S2 or dipole moments dS0 S1 and dS1 S2 in the rotating wave approximation (RWA)
Our numerical results show that electronic structures, transition dipole moments, HOMO–LUMO energy gaps, and pump rates are influenced by the position of the substituent group, and 3-DCDBA, with the position of the substituent group at the meta position, has preferable nonlinear absorption properties, with a change in propagation distance and particle number density of the medium
Summary
Materials with excellent two-photon absorption (TPA) properties have attracted a tremendous amount of interest due to their versatile applications in frequency up-conversion lasing [1,2,3], 3-D microfabrication [4], two-photon fluorescence imaging [5], two-photon photodynamic therapy [6,7], and especially optical limiting (OL) [8,9,10]. During the past few decades, with the widespread application of intense lasers as light sources, optical power liming from hazards of the intense laser beam has become an urgent need for instrument protection, eye protection, and optical biology [11]. It is an important task for researchers to design and synthesize optical limiters with a large TPA cross section [12,13]. The dynamical TPA cross sections of the compounds are obtained, and the influence of pulse or medium parameter on the dynamical TPA cross section is compared
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