Three-photon Absorption Properties Research Articles

Three-Photon Absorption and Upconversion Fluorescence Properties of Series 1,3,4-Oxadiazole Derivatives

A newly synthesized 1,3,4-oxadiazole derivatives have been studied using a femtosecond Ti:sapphire laser system. The series molecules present strong three-photon absorption and frequency upconversion fluorescence at wavelengths from 1205nm to 1575nm. Furthermore, there is no proportional relationship between three-photon absorption cross sections and the chemical structure transformation from monomer, dimer to trimer. Effective charge-transfer distance by π-conjugation bonds may be the contributing factor. In the experimental design, the far-field intensity distribution of femtosecond laser beam has been taken into account. We give the optimized analytical solution of nonlinear transmission in a three-photon absorption (3PA) process when the incident beam has a Gaussian transverse spatial profile.

Novel fluorophore based on a multi-substituted olefin skeleton with enhanced three-photon absorption in the femtosecond regime

A new multipolar fluorophore based on a multi-substituted olefin skeleton that possesses strong three-photon absorption and optical-limiting properties in the femtosecond regime has been designed and synthesized; this archetype suggests a new strategy to further optimize molecular structures toward enhanced nonlinear absorptivities based on known materials.

Thiophene-fluorene derivatives with high three-photon absorption activities and their application to optical power limiting

The three-photon absorption (3PA) properties of two thiophene-fluorene derivatives (abbreviated as MOTFTBr and ATFTBr) have been determined by using a Q-switched Nd:YAG laser pumped wish 38ps pulses at 1064nm in DMF. The measured 3PA cross-sections are 152x10(-78)cm(6)s(2) and 139x10(-78)cm(6)s(2), respectively. The optimized structures were obtained by AM1 calculations and the results indicate that these two molecules show nonplanar structures, and attaching different donors has different effects on the molecular structure. The charge density distributions during the excitation were also systematically studied by using AM1 method. In addition, an obvious optical power limiting effect induced by 3PA has been demonstrated for both derivatives.

Theoretical study of one-, two-, and three-photon absorption properties for a series of Y-shaped molecules

In this paper, the equilibrium geometries, one-, two-, and three-photon absorption properties, and the transition nature of a series of Y-shaped molecules which possess an imidazole-thiazole core have been theoretically studied by using the parametrization model 3 and Zerner's intermediate neglect of differential overlap methods. Our calculated results have confirmed the experimental findings that the investigated molecules are all promising multiphoton absorption materials and both the two-photon absorption and the three-photon absorption cross sections are seriatim increscent along with the increase of the electron-donor strength. The nonlinear optical phenomenon originates from the intramolecular charge transfer within the pi-conjugated system. The calculated results indicate that the heterocyclic core increases the two- and three-photon absorption cross sections due to its pi-excessive nature. So it can provide more free electrons to enlarge the charge transfer within the molecule system. In addition, the design of Y shape and the sulfonyl-based electron-accepting group play a part in the enhancement of multiphoton absorption. It is notable that molecules with heterocyclic core will provide favorable condition for multiphoton absorption applications.

Degenerate two-/three-photon absorption and optical power-limiting properties in femtosecond regime of a multi-branched chromophore

The degenerate two- and three-photon absorption properties of a multi-branched chromophore were investigated in the femtosecond regime utilizing white-light continuum and nonlinear transmission techniques. The experimental results show that the studied multi-branched structure exhibits relatively strong and broad two- and three-photon absorption bands in the near infra-red (IR) region. It is demonstrated that a highly conjugated molecular structure based on a symmetrically substituted skeleton would possess promoted molecular nonlinear absorptivities within the studied spectral region. Both two- and three-photon absorption-based optical power-limiting properties in the femtosecond time domain of this model compound were also characterized. The results indicate that a multi-chromophoric structure with expanded π-conjugation could be an effective multi-photon absorber and might be used as a single-component material system for quick-responsive and broadband optical-suppressing related applications, especially when under ultrashort laser pulses.

Three-photon absorption properties of two novel fluorene-based derivatives

Two novel fluorene_based derivatives 9_(7_(9H_carbazol_9_yl)_9, 9_bis (2_ethylhexyl)_9H_fluorene_2_yl)_9H_carbazole (abbreviated as DCZF) and 2, 7_bis (4_metho xystyryl)_9, 9_bis (2_ethylhexyl)_9H_fluorene (abbreviated as BMOSF) were synthe sized and their linear absorption and one_photon fluorescence spectra were measu red. We used a 38ps, 1064nm Nd:YAG pulsed laser operating at 10 Hz to invest igate the three_photon absorption (3PA) properties of the two compounds. The re sults show that the linear absorption band of the two compounds is from 270—420 nm with absorption peaks at 330 and 380nm. The fluorescence bands were locat ed in the blue_violet region with the peak wavelengths of 369 and 442 nm, and s mall Stokes shifts were observed. Nonlinear absorption coefficients γ deriv ed from 3PA fitting curves are 678 and 592×10-20 cm3/ W2, respectively. Large optical power limiting induced by 3PA has also been demonstr ated for both dyes. When the incident irradiances reach 8 and 6 GW/cm2, t he limiting nonlinear transmissions of DCZF and BMOSF can reach to 30% and 45%, respectively.