Multi-Order Investigation of the Nonlinear Susceptibility Tensors of Individual Nanoparticles

Abstract

We use Hyper Rayleigh Scattering and polarization resolved multiphoton microscopy to investigate simultaneously the second and third-order nonlinear response of Potassium Niobate and Bismuth Ferrite harmonic nanoparticles. We first derive the second-to-third harmonic intensity ratio for colloidal ensembles and estimate the average third-order efficiency of these two materials. Successively, we explore the orientation dependent tensorial response of individual nanoparticles fixed on a substrate. The multi-order polarization resolved emission curves are globally fitted with an analytical model to retrieve individual elements of susceptibility tensors.

Preparation and Preliminary Nonlinear Optical Properties of BiFeO3 Nanocrystal Suspensions from a Simple, Chelating Agent-Free Precipitation Route

“…Nonlinear optical properties were measured by probing the second and third harmonic scattering signals as previously reported [12,35,36] except that the excitation source is here provided by a tunable (700-1300 nm) femtosecond Laser (Insight X3 Spectra-Physics) vertically polarized. SH and TH signals are collected perpendicularly to the fundamental beam and focused through two 5 cm focal length lenses onto the slit of a spectrometer (Andor Shamrock 193) combined to a CCD camera (Andor iDus 401 BVF).…”

“…BiFeO 3 exhibits a rhombohedrally distorted perovskite structure (space group R3c) for which noncentrosymmetry arises from the rotation of the oxygen octahedrons around the pseudocubic [111] axis [3,4]. Among potential applications based on bismuth ferrite, photocatalysis under ambient light [5], nonvolatile memory [6], spintronics [7,8], and energy harvesting [9] can be mentioned as well as its increasing interest in bioimaging due to intrinsic, very high second [10,11] and third harmonic [12] properties. Harmonic nanoparticles (HNPs) [13] based on BiFeO 3 not only display a low cytotoxicity [14] but also display several "optical" advantages in terms of excitation wavelength tunability for deep-imaging [15], of photostability for long-term observations [16,17], and of improved sensitivity due to specific harmonic signatures against endogenous signals [18][19][20].…”

Nonlinear Diffuse fs-Pulse Reflectometry of Harmonic Upconversion Nanoparticles

“…Additional cogitable subjects include higher harmonic generation beyond frequency-tripling, analysis of mixtures of two or more substances, or specific tailoring of illuminants for industrial purposes. It may further serve as an important additional tool for the determination of nonlinear optical coefficients when combined with polarization-dependent microscopy [42]. Extension to a vast array of nanoscaled materials, each with their very own properties, can thus be easily realized and will therefore likely be subject to future investigations.…”

Application of a reflective microscope objective for multiphoton microscopy

“…Reflective objectives (ROs), such as Schwarzschild objectives (Burch, 1947), utilise reflecting mirrors to provide an uniform focus over a wide spectral bandwidth (Barer et al, 1949;Grey & Lee, 1949). ROs have also been incorporated in MPM applications, where they have replaced traditional SOs to combine beams at far and distinct wavelengths (Raghunathan et al, 2011;Schmidt et al, 2016). In one case of sum-frequency generation (SFG) microscopy, an RO was used to collinearly focus 3.39 μm and 775 nm wavelength beams, leading to SFG signals between 625 and 650 nm (Raghunathan et al, 2011).…”