Very large molecular two- and three-photon absorption cross-sections are achieved by appending ligated bis(diphosphine)ruthenium units to oligo(p-phenyleneethynylene) (OPE)-based "stars" with arms up to 7 phenyleneethynylene (PE) units in length. Extremely large three- and four-photon absorption cross-sections, through the telecommunications wavelengths range and beyond, are obtained for these complexes upon optimizing OPE length and the ruthenium-coordinated peripheral ligand. Multi-photon absorption (MPA) cross-sections are optimized with stars possessing arms 2 PE units in length. Peripheral ligand variation modifies MPA merit and, in particular, 4-nitrophenylethynyl ligand incorporation enhances maximal MPA values and "switches on" four-photon absorption (4PA) in these low molecular-weight complexes. The 4-nitrophenylethynyl-ligated 2PE-armed star possesses a maximal four-photon absorption cross-section of 1.8×10 cm s at 1750 nm, and significant MPA activity extending beyond 2000 nm.
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http://dx.doi.org/10.1002/chem.201702039 | DOI Listing |
Multi-photon absorption in the second near-infrared (NIR-II) regime has attracted extensive attention due to biological imaging and frequency-upconverted lasing applications. We report the dispersion of four-photon absorption (4 PA) response in pristine and Ga-doped ZnO single crystals over the spectral range 1180-1350 nm. Femtosecond Z-scan results demonstrate that Ga doping can significantly enhance the 4 PA coefficient β of ZnO.
View Article and Find Full Text PDFWe analytically derive the formulas of the threshold pump intensity and the range of possible detuning for the initiation of the pure quartic platicon (PQP) in the presence of multiphoton absorption, free-carrier absorption, and free-carrier dispersion. Theoretical investigations demonstrate a feasible approach for the excitation of PQP in the normal quartic dispersion regime via the free-carrier effects in platforms such as silicon, germanium, and their derivates. Due to the time-variant nonlinear loss related to free-carrier absorption or additional nonlinear detuning induced by free-carrier plasma dispersion, PQP can be generated through turn-key or laser frequency scanning schemes in both the three- and four-photon absorption regimes.
View Article and Find Full Text PDFA misprint in our manuscript published in Opt. Express32(5), 7030 (2024) 10.1364/OE.
View Article and Find Full Text PDFACS Nano
October 2024
College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, P. R. China.
High-resolution visualization of the deep brain is still a challenging and very significant issue. Multiphoton microscopy (MPM) holds great promise for high-spatiotemporal deep-tissue imaging under NIR-III and NIR-IV excitation. However, thus far, their applications have been seriously restricted by the scarcity of efficient organic probes.
View Article and Find Full Text PDFOpen-aperture Z-scan measurements have been carried out to investigate the three-photon (3 PA) and four-photon absorption (4 PA) coefficients at 800 nm and 1030 nm wavelengths, respectively in congruent and stoichiometric lithium niobate (cLN, sLN) with different concentrations of Mg doping. The laser pulse duration at the two wavelengths were 40 and 190 fs. The peak intensity inside the crystals varied between approximately 110 and 550 GW/cm.
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