Dielectric metasurfaces have recently shown to be an excellent candidate for efficient frequency mixing at the nanoscale due to the excitation of Mie resonances. Among various dielectric materials, GaAs-based nanostructures have been reported to have high-efficiency of second-order nonlinear processes due to their high quadratic nonlinear susceptibility. Efficient frequency up-conversion can thereby be realised in GaAs-based metasurfaces through the process of sum-frequency generation (SFG), thereby opening new opportunities for nonlinear imaging and infrared vision not possible before. Here we demonstrate for the first time, infrared imaging based on nonlinear mixing of an infrared image with a pump beam in a GaAs resonant metasurface. The nonlinear mixing process generates visible images (Fig. 1a), which can be time resolved with femtosecond resolution and can be observed on a conventional CMOS sensor. Our results open new opportunities for the development of compact night-vision devices operating at room temperature and have multiple applications in defense and life sciences.
The photo-excited luminescence response of solutions (in organic solvent) of eight selected organometallic coordination complexes of Iridium Ir(III) ion is studied upon irradiation with high-intensity short-pulse (nanosecond) ultraviolet laser irradiation, as well as by ultra-high-intensity ultrashort (femtosecond) laser pulses in the visible (violet). The Ir-complexes are cyclometalated and contain bis-phenylbenzothiazole as a main ligands and auxiliary β-diketone ligands, and they are intended to be used as luminescent materials and sensitive nanoprobes, e.g., in organic optoelectronics, sensorics, mechatronics and laser fluorescent microscopy. The results obtained by laser spectroscopy of dilute (10–5 M) solutions of the examined Ir-complexes show that they are efficient triplet emitters whose photo-excited emission is proper for fluorometric, optoelectronic and photonic applications.
In this work we study the influence of the additional second-order dispersion introduced in sub-45 femtosecond laser pulses by intentional misaligning a folded 4-f otherwise dispersionless system. The theoretically calculated pulse durations are found to be in a good agreement with the respective experimental data from frequency-resolved optical gating measurements.
In this work we report experimental measurement of an intentionally introduced pulse front tilt on femtosecond laser pulses by using an inverted field correlator/interferometer. The results obtained with a low-dispersion diffraction grating are in good qualitative agreement with the data from a previously developed analytical model and with these from an independent interferometric measurement.
In this work we study the evolution and interaction of semi-infinite dark beams carrying edge-screw phase dislocations in self-focusing and self-defocusing local Kerr nonlinear media aiming to find appropriate conditions to control the process of fusion/crossing the dark beams in a way suitable for probe-beam cross-switching. We show that a quasi-infinite vortex dipole (dipole much longer than the background beam) evolves into a one-dimensional dark spatial soliton with vanishing transverse velocity. Single semi-infinite fractional dipole develops snake instability near the dark beam end. Depending on their phase profiles, four parallel semi-infinite fractional vortex dipoles aligned to initially form two dark stripes can evolve into two different ‘cross-connects’ able to branch and route probe optical beams. Perpendicular probe beam propagation in the optically-induced guiding structures is modeled and analyzed with respect to the branching efficiency to respective virtual output channels for both self-focusing and self-defocusing conditions.
In this work we study the influence of the additional second- and third-order dispersion introduced in a femtosecond
laser cavity by varying the beam's penetration into a prism of the double-pass intracavity prism compressor on the
output pulse duration, as well as on the emission spectral bandwidth and its central wavelength. The theoretically
calculated pulse durations are found to be in a good agreement with the respective experimental data from
frequency-resolved optical gating and interferometric autocorrelation measurements.
In this work, by using 4x4 ray-pulse matrices, we analyze the influence of the position of the output diffraction grating in
4f- and 2f-2f-systems with respect to the eventually introduced group-delay dispersion, spatial and angular chirp. We
show that in the 4f-configuration, in contrast to the 2f-2f-setup, the grating offset does not cause angular chirp and pulse
front tilt. We theoretically derive an expression for the interferometric autocorrelation signal in the presence of an
arbitrary pulse-front tilt.
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