In this work, the second- and third-order nonlinear optical response of spin-deposited thin films of three different push-pull side chain azobenzene polymers is investigated by the second- and third-harmonic Maker fringes techniques using 30 ps laser pulses at a fundamental wavelength of 1064 nm. Measurements were carried out before and after aligning the chromophores by corona poling of the films, while different polarization configurations have been utilized. Strong dependence of the response upon the structure of the systems has been found, which is related to the different charge transfer within the molecules. The reported findings are compared with already published results.

We present the nonlinear absorption investigation of an electroactive ligand and two ruthenium and iron metal complexes under 532 nm, 30 ps laser excitation, by the "open aperture" Z-scan technique. Significant nonlinear optical parameters have in all cases been measured, while the nonlinear attribute has been found to change from saturable to reverse saturable absorption between the initial ligand and its complexes.

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We present the third order nonlinear optical study of tetrathiafulvalene-based molecular corners. Degenerate four-wave mixing measurements have been done to provide information about the magnitude and the origin of the nonlinearity, while the nonlinear absorption has been separately measured by performing “open aperture” Z-scan measurements. The response has been found to be strongly dependent upon the structure of the molecular corners.

Surface enhanced infrared absorption (SEIRA) spectroscopy and surface plasmon resonance (SPR) make possible, thanks to plasmonics nanoantennas, the detection of low quantities of biological and chemical materials. Here, we investigate the infrared response of 2,4-dinitrotoluene deposited on various arrays of closely arranged metal-insulator-metal (MIM) resonators and experimentally show how the natural dispersion of the complex refractive index leads to an intertwined combination of SEIRA and SPR effect that can be leveraged to identify molecules. They are shown to be efficient for SEIRA spectroscopy and allows detecting of the dispersive explosive material, 2,4-dinitrotoluene. By changing the in-plane parameters, a whole spectral range of absorptions of 2,4-DNT is scanned. These results open the way to the design of sensors based on SEIRA and SPR combined effects, without including a spectrometer.