Time‐Resolved Nonlinear Diffuse Femtosecond‐Pulse Reflectometry Using Lithium Niobate Nanoparticles with Two Pulses of Different Colors

Abstract

Time‐resolved nonlinear optical sum‐frequency generation (SFG) of two differently colored, infrared (sub‐)picosecond laser pulses is studied by means of nonlinear diffuse femtosecond‐pulse reflectometry using lithium niobate nanoparticle pellets. The visible SFG emission exhibits an asymmetric pulse shape in the time domain which is explained within the framework of light propagation in random media. The analysis of the spectro‐temporal data set indicates that LiNbO3 nanoparticle pellets can be used for an alternative type of an optical correlator, e.g., for the determination of a pulse's chirp parameter. This finding is generalized by means of numerical simulations. As a result, ultrashort pulse shapes can now be predicted inside nanoscaled, densely packed media with a nonlinear optical response on a comprehensive basis, giving rise to a number of prospective fields of applications.

Manipulating Nonlinear Optical Response via Domain Control in Nanocrystal‐in‐Glass Composites

“…In stark contrast to the conventional optical pulse duration measurement method such as standard autocorrelation and GRENOUILLE, the proposed strategy provides notable advantages, including high accuracy and easy operation (see Table S5, Supporting Information for details). [38][39][40] In addition, the approach also enables to remove the alignment constraints imposed by the complicated mechanical devices.…”

NIR-to-NIR Imaging: Extended Excitation Up to 2.2 μm Using Harmonic Nanoparticles with a Tunable hIGh EneRgy (TIGER) Widefield Microscope

“…In these cases, two light pulses of different photon energies ω 1 , ω 2 are mixed in the nanoparticle and generate either the sum (ω 1 + ω 2 ) or the difference frequency (ω 1 − ω 2 ) at the output. The sum and difference frequency conversion in HNPs has already been demonstrated in previous studies [44,45] and appears concurrently to harmonic generation, as shown in [45], thus extending the concept of multi-harmonic imaging, which was previously limited to the simultaneous acquisition of SHG and THG [17,25]. SFG and DFG give even more freedom in the tailoring of the excitation and emission according to the biological windows.…”

Gap-Free Tuning of Second and Third Harmonic Generation in Mechanochemically Synthesized Nanocrystalline LiNb1−xTaxO3 (0 ≤ x ≤ 1) Studied with Nonlinear Diffuse Femtosecond-Pulse Reflectometry

“…It was shown that the method is sensitive to particles in the upper layers of the surface, as the penetration depth of the pulse into the powder sample is limited to a few tens of microns. At the same time, it is independent of the light polarization, as the incident polarization state is lost after multiple scattering events [21,26]. In our case, the method is used to demonstrate gap-free emission of SHG and THG, as well as to validate the harmonic nature of the generated signals in LNT nanocrystallites.…”