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With the miniaturization of electronic-based devices, the foreseen potential of new optical nanoprobes and the assessment of eventual size and shape effects, elaboration of multifunctional noncentrosymmetric nanocrystals with ferroelectric, pyroelectric, piezoelectric, and nonlinear optical properties are the subject of an increasing research interest. Here, the recent achievements from the solution-based methods (coprecipitation in homogeneous and nanostructured media, sol-gel processes including various chemistries and hydro/solvothermal techniques) to prepare 0-D perovskite and nonperovskite oxides in the 5-500 nm size range are critically reviewed. To cover a representative list of covalent- and ionic-type materials, BaTiO

Whereas most of the reports on the nonlinear properties of micro- and nanostructures address the generation of distinct signals, such as second or third harmonic, we recently demonstrated that the novel generation of dual output lasers developed for microscopy can readily increase the accessible parameter space and enable the simultaneous excitation and detection of multiple emission orders such as several harmonics and signals stemming from various sum and difference frequency mixing processes. [1] This rich response, which in our case features 10 distinct emissions and encompasses the whole spectral range from the deep ultraviolet to the short-wave infrared region, is demonstrated using various nonlinear oxide nanomaterials while being characterized and simulated temporally and spectrally.

Hybrid nanoparticles composed of an efficient nonlinear optical core and a gold shell can enhance and tune the nonlinear optical emission thanks to the plasmonic effect. However the influence of an incomplete gold shell, i.e., isolated gold nano-islands, is still not well studied. Here LiNbO3 (LN) core nanoparticles of 45 nm were coated with various densities of gold nano-seeds (AuSeeds). As both LN and AuSeeds bear negative surface charge, a positively-charged polymer was first coated onto LN. The number of polymer chains per LN was evaluated at 1210 by XPS and confirmed by fluorescence titration. Then, the surface coverage percentage of AuSeeds onto LN was estimated to a maximum of 30% using ICP-AES. The addition of AuSeeds was also accompanied with surface charge reversal, the negative charge increasing with the higher amount of AuSeeds. Finally, the first hyperpolarizability decreased with the increase of AuSeeds density while depolarization values for Au-seeded LN were close to the one of bare LN, showing a predominance of the second harmonic volumic contribution. ispartof: NANOMATERIALS vol:11 issue:4 ispartof: location:Switzerland status: published

International audience; Whereas most of the reports on the nonlinear properties of micro- and nanostructures address the generation of distinct signals, such as second or third harmonic, here we demonstrate that the novel generation of dual output lasers recently developed for microscopy can readily increase the accessible parameter space and enable the simultaneous excitation and detection of multiple emission orders such as several harmonics and signals stemming from various sum and difference frequency mixing processes. This rich response, which in our case features 10 distinct emissions and encompasses the whole spectral range from the deep ultraviolet to the short-wave infrared region, is demonstrated using various nonlinear oxide nanomaterials while being characterized and simulated temporally and spectrally. Notably, we show that the response is conserved when the particles are embedded in biological media opening the way to novel biolabeling and phototriggering strategies.

This chapter describes the use of a family of dielectric metal oxide nanoparticles (NPs), harmonic NPs, characterized by a noncentrosymmetric crystal structure and high nonlinear optical efficiencies, and displaying a very rich nonlinear response. The selectivity in the retrieval of harmonic NPs in optically congested environments, besides the aforementioned minimization of fluorescence hindrance by wavelength selection, can be further improved using a multiorder harmonic approach. To date, the most successful and widespread ones are those based on quantum dots and upconversion NPs for imaging, because of their bright luminescence emission, and those using metal particles for sensing, thanks to the sensitivity of surface plasmon scattering to the local environment. The simultaneous collection and analysis of these signals allow developing refined detection approaches for increased sensitivity and selectivity in demanding imaging applications. Nonlinear optical observables present various advantages, including the possibility to detect background-free parametric signals at excitation wavelengths which depose no or minimal energy on the sample under investigation.

Pure α-La(IO3)3 and α-La0.85Er0.15(IO3)3 nanocrystals were synthesized by a microwave-assisted hydrothermal method leading to a reaction yield of 87 ± 4%. Electron microscopy and dynamic light scattering characterizations provide evidence for the formation of nanocrystals with an average size of 45 ± 10 nm for α-La(IO3)3 and 55 ± 10 nm for α-La0.85Er0.15(IO3)3. When dispersed in ethylene glycol, the nanocrystal suspensions exhibit second-harmonic generation under near-infrared excitations at 800 and 980 nm whereas additional photoluminescence by up-conversion is simultaneously observed in the case of α-La0.85Er0.15(IO3)3 nanocrystals. Quantitative assessments of the second-harmonic generation efficiency from second-harmonic scattering experiments at 1064 nm result in relatively high ⟨ d⟩ coefficients measured at 8.2 ± 2.0 and 8.0 ± 2.0 pm V-1 for α-La(IO3)3 and α-La0.85Er0.15(IO3)3, respectively. The relative intensity between second-harmonic generation and photoluminescence is discussed following the excitation wavelength.

While chemotherapy is one of the most used treatments in oncology, the systemic administration of chemotherapeutics generally results in undesired damages to healthy tissues and cells, side effects such as severe nausea and leukopenia, and reduced efficacy due to multidrug resistance and poor target accessibility. The limitations of conventional chemotherapy formulation have prompted the development of alternative nanomaterials‐based strategies to achieve targeted and stimuli sensitive payload delivery to reach optimal local drug concentration at tumor sites. In this study, the anticancer drug chlorambucil (Clb) was conjugated to the surface of silica coated lithium niobate (LNO) harmonic nanoparticles (HNPs) using a photocaging tether based on coumarin‐4‐yl methyl derivative. Upon laser pulsed femtosecond irradiation at 790 nm, the second harmonic emission from the metal oxide core induced the efficient release of Clb, with concomitant contribution from the nonlinear absorption of the coumarin (CM)‐based moiety.

We introduce a nonlinear all-optical theranostics protocol based on the excitation wavelength decoupling between imaging and photoinduced damage of human cancer cells labeled by bismuth ferrite (BFO) harmonic nanoparticles (HNPs). To characterize the damage process, we rely on a scheme for in situ temperature monitoring based on upconversion nanoparticles: by spectrally resolving the emission of silica coated NaGdF4:Yb3+/Er3+ nanoparticles in close vicinity of a BFO HNP, we show that the photointeraction upon NIR-I excitation at high irradiance is associated with a temperature increase >100 °C. The observed laser–cell interaction implies a permanent change of the BFO nonlinear optical properties, which can be used as a proxy to read out the outcome of a theranostics procedure combining imaging at 980 nm and selective cell damage at 830 nm. The approach has potential applications to monitor and treat lesions within NIR light penetration depth in tissues.

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International audience; We report the microwave-assisted hydrothermal synthesis of α-La(IO3)3 nanocrystals doped with Yb 3+ and Er 3+ ions, along with their structural and optical characterizations. 50-nm sized α-La0.9-xYb0.1Erx(IO3)3 nanocrystals with x = 0.005, 0.01 and 0.02 were synthesized and dispersed in ethylene glycol. The as-obtained suspensions exhibit both Second Harmonic Generation (SHG) signal and up-conversion photoluminescence (UC-PL) without interplay between the two signals under near-infrared resonant excitation. The relative intensity of SHG and UC-PL emission can be modulated according to the excitation wavelength. The most intense UC-PL signal is obtained from a 980-nm excitation, thanks to the sensitization of Er 3+ by Yb 3+. 2

The design of stimuli-responsive nanocarriers has raised much attention to achieve higher local concentration of therapeutics and mitigate the appearance of drug resistance. The combination of imaging properties and controlled photorelease of active molecules within the same nanoconjugate has a great potential for theranostic applications. In this study, a system for NIR light-triggered release of molecular cargos induced by the second harmonic emission from bismuth ferrite harmonic nanoparticles (BFO HNPs) is presented. Silica-coated BFO HNPs were covalently conjugated to a photocaging tether based on coumarin (CM) and l-tryptophan (Trp) as a model molecular cargo. Upon femtosecond pulsed irradiation at 790 nm, Trp was efficiently released from the NP surface in response to the harmonic emission of the nanomaterial at 395 nm. The emitted signal induced the photocleavage of the CM-Trp carbamate linkage resulting in the release of Trp, which was monitored and quantified by ultrahigh performance liquid chromatography-mass spectrometry (UHPLC-MS). While a small fraction of the uncaging process could be attributed to the nonlinear absorption of CM derivatives, the main trigger responsible for Trp release was established as the second harmonic signal from BFO HNPs. This strategy may provide a new way for the application of functionalized HNPs in dual imaging delivery theranostic protocols.

Pure α-La(IO

Both coherent Third Harmonic Generation (THG) at the interfaces of a cuvette filled with a nanocrystal suspension and incoherent Second and Third Harmonic Scattering (THS) from the suspension volume have been studied to quantitatively assess the orientation-averaged third-order susceptibility 〈 χ N P s ( 3 ) 〉 of ZnO. These two complementary experimental approaches are based on different calibration routes with a nanocomposite model and fused-silica as a reference material for THG, and pNa molecules for THS. Similar and consistent absolute values of 〈 χ N P s ( 3 ) 〉 (above 10 − 18 m2/V2) are derived and discussed according to the particular orientation averaging procedure that holds for each experimental configuration for a 1064 nm excitation wavelength.

The absence of photobleaching, blinking, and saturation combined with a high contrast provides unique advantages of higher-harmonic generating nanoparticles over fluorescent probes, allowing for prolonged correlation spectroscopy studies. We apply the coherent intensity fluctuation model to study the mobility of second harmonic generating nanoparticles. A concise protocol is presented for quantifying the diffusion coefficient from a single spectroscopy measurement without the need for separate point-spread-function calibrations. The technique's applicability is illustrated on nominally 56 nm LiNbO3 nanoparticles. We perform label-free raster image correlation spectroscopy imaging in aqueous suspension and spatiotemporal image correlation spectroscopy in A549 human lung carcinoma cells. In good agreement with the expected theoretical result, the measured diffusion coefficient in water at room temperature is (7.5 +/- 0.3) mu m(2)/s. The diffusion coefficient in the cells is more than 10(3) times lower and heterogeneous, with an average of (3.7 +/- 1.5) X 10(-3) mu m(2)/s. This research was supported by the Research Foundation Flanders (Fonds Wetenschappelijk Onderzoek, project G092915FWO) and by the Interuniversity Attraction Poles Program (IAP FS2 P7/05, Functional Supramolecular Systems) initiated by the Belgian Science Policy Office. The authors are grateful to Prof. Dr. J. D'Haen for the SEM image, to Dr. N. Smisdom for fruitful discussions, and to Dr. R. Paesen and Dr. N. Smisdom for the design of the polarization unit. Research in P.P.'s laboratory was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Preparation of stable BiFeO3 nanocrystal suspensions through a simple, low-cost precipitation technique is described. Amorphous precursors are first precipitated from metal nitrate salts in highly basic KOH solutions, and a short high-temperature annealing step is then performed to induce crystallization. Nanoparticles are characterized by X-ray diffraction (XRD), TEM, DLS and ζ-potential measurements, and the synthesis conditions optimized after a systematic variation of the KOH concentration within the range of 1–12 M. The presence of residual impurities (mainly Bi25FeO39 and Bi2Fe4O9) quantified from XRD and mean nanocrystal size is found to be strongly influenced by the initial KOH solution content. A concentration at about 3–4 M is optimal in terms of BiFeO3 phase-purity and nanocrystal size. Stability of aqueous dispersions of the amorphous precursors and of the purest crystallized nanoparticles is also characterized between pH = 2 and pH = 13. After preparation of stable, almost phase-pure BiFeO3 nanocrystal suspensions, second and third harmonic scattering (SHS and THS) at excitation wavelengths of 1064 nm and 1250 nm are reported from nonlinear optical scattering measurements and compared with other recently published literature values.

Surface plasmon resonant nanoantennas can confine incident energy onto two-dimensional (2D) transition metal dichalcogenides (TMD) to enhance efficiency of harmonic conversion to higher energies, which is otherwise limited by the intrinsic A-scale interaction length. Second harmonic generation (SHG) from nanoantenna-decorated 2D TMD was heuristically examined with hyper Rayleigh scattering (HRS), multi-photon microscopy, electron energy loss spectroscopy (EELS), and discrete dipole computation. HRS experimentally quantified the frequency dependence of the second-order nonlinear susceptibility, χ (2) , for liquid-exfoliated WS2. Measured χ(2) fell within 21% of independent density functional theory (DFT) calculations, overcoming the known 100-1000x overestimation of microscopy approaches. EELS supported design of nanoantennas for integration with TMD. Overall SHG conversion efficiencies from chemical vapor-deposited (CVD) 4×105 nm2 MoS2 crystals on silicon dioxide were enhanced up to 0.025 % W-1 in the presence of by single 150 nm Au nanoshell monomers and dimers, ostensibly due to augmented local plasmonic fields.

We demonstrate the simultaneous generation of second, third, and fourth harmonic from a single dielectric Bismuth Ferrite nanoparticle excited by a telecom fiber laser at 1560 nm. We first characterize the signals associated with different nonlinear orders in terms of spectrum, excitation intensity dependence, and relative signal strengths. Successively, on the basis of the polarization-resolved emission curves of the three harmonics, we discuss the interplay of susceptibility tensor components at the different orders and we show how polarization can be used as an optical handle to control the relative frequency conversion properties., Comment: include S.I. section at the end of the main pdf file

A tunable wavelength Hyper Rayleigh Scattering setup was developed to assess and compare Second Harmonic Scattering from Lithium Niobate, Zinc Oxide and Bismuth Ferrite nanocrystal suspensions in the 730–1150 nm excitation range.

We demonstrate the simultaneous generation of more than four harmonics from individual dielectric nanoparticles excited by a telecom fiber laser at 1560. We discuss the possibility to control their relative intensities by the laser polarization.

International audience

We present two new synthetic routes for bismuth ferrite harmonic nanoparticles (BiFeO3 HNPs). Both phase-pure and mixed phase BiFeO3 materials were produced after improvement of the solvent evaporation and sol-gel combustion routes. Metal nitrates with a series of dicarboxylic acids (tartronic, tartaric and mucic) were used to promote crystallization. We found that the longer the carbon backbone with a hydroxyl group attached to each carbon, the lower the annealing temperature. We also demonstrate that nanocrystals more readily formed at a given temperature by adding glycerol but to the detriment of phase purity, whereas addition of NaCl in excess with mucic acid promotes the formation of phase-pure, monocrystalline nanoparticles. This effect was possibly associated with a better dispersion of the primary amorphous precursors and formation of intermediate complexes. The nanoparticles have been characterized by XRD, TEM, ζ-potential, photon correlation spectroscopy, two-photon microscopy and Hyper-Rayleigh Scattering measurements. The improved crystallization leads to BiFeO3 HNPs without defect-induced luminescence and with a very high averaged second harmonic efficiency (220 pm/V), almost triple the efficiency previously reported. This development of simple, scalable synthesis routes which yield phase-pure and, crucially, monocrystalline BiFeO3 HNPs demonstrates a significant advance in engineering the properties of nanocrystals for bio-imaging and diagnostics applications.

Hyper Rayleigh scattering (HRS) was used to measure the second-order nonlinear susceptibility, χ

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.

International audience; SiC nanoparticles by carbothermal reduction show promising properties in terms of second harmonic and multiphoton excited luminescence. In particular, we estimate a nonlinear efficiency < d > = 17 pm/V, as obtained by Hyper Rayleigh Scattering. We also present results of cell labelling to demonstrate the potential use of SiC nanoparticles for nonlinear bioimaging by simultaneous detection of second harmonic and luminescence.

response, often referred to as harmonicnanoparticles (HNPs). HNPs feature a series of properties which distinguish them from otherphotonics nanoprobes (quantum dots, up-conversion nanoparticles, noble metal particles). HNPsemission is inherently nonlinear and based on the efficient generation of harmonics as opposed tofluorescence or surface plasmon scattering. In addition, the fully coherent signal emitted byHNPs together with their polarization sensitive response and absence of resonant interactionmake them appealing for several applications ranging from multi-photon (infrared) microscopyand holography, to cell tracking and sensing.Keywords: multiphoton microscopy, second harmonic generation, third harmonic generation,nonlinear optics, nanophotonics, perovskites(Some figures may appear in colour only in the online journal)1. IntroductionSince the advent of ultrafast lasers in the early nineties andrelated availability of high peak power pulses at compara-tively low energies, the investigation of nonlinear opticalresponse have become a widespread activity resulting ininnovative applications. In particular, in the field of imagingthis has led to the introduction of multi-photon microscopy byW Webb [1]. This technique, as compared to one-photonexcited fluorescence microscopy, features increased imagingdepth, no out-of-focus bleaching, and spatial resolutioncomparable to confocal techniques without compromise insensitivity. The latest technological advancements in this fieldare related to its extension towards longer wavelengths,facilitated by the timely introduction of novel tunable sourcesin the 0.7–1.3 μm spectral range and new optical componentswith optimized performances in this region (microscopeobjectives, acousto-optic modulators, ...). Although these newinfrared tunable devices are supposedly more adapted forimaging through thick (living) samples because of reducedscattering [2–4], the available choice of imaging targets(fluorescent molecules, dyes) with two-photon absorptionbands >1200nm is very limited.Nanoparticle-based labelling, which is sometimes pre-ferred over other approaches for its superior photo-stability,brightness, and chemical selectivity usually requires two-photon interactions in the 700–900nm range, with a fewnotable exceptions [5]. However most optically active labelsmay suffer from bleaching and blinking and their use inbiological research might be prevented because of low bio-compatibility. For these reasons, since 2006, several researchgroups worldwide have proposed a complementary approach

Commonly called the "silicon of photonics", lithium niobate (LiNbO3) at the nanoscale is the subject of this work. These so-called harmonic nanocrystals, due to their non-centrosymmetric crystal structure and excellent non-linear optical properties, can be used as contrast agents in multiphoton biomedical imaging for better diagnosis and targeted release of therapeutic agents. The synthesis of LiNbO3 nanocrystals under solvothermal conditions, from alkoxide precursors, is described with a special focus on the fine understanding of reaction mechanisms. Ultimately, this understanding aims to better control the nanocrystal size and shape polydispersity by modifying nucleation and growth rates as desired. For non-aqueous syntheses, since water is neither added nor generated in the reaction medium, it is shown that thermal decomposition of the chosen ethoxide precursor governs the formation kinetics of the monomers and leads, in this case, to the production of nano-platelets. On the other hand, a controlled addition of glycols, such as butane-1,4-diol and pentane-1,5-diol, makes it possible to prepare quasi-spherical nanocrystals with a smaller size and shape distribution due to a better carbocation stability, thus favoring a shorter and more intense nucleation step. For the hydrolytic route, the variation of the hydrolysis rate h leads either to polymeric gels (h1) whose solvothermal treatment produces nanocrystals of low and high polydispersity, respectively. Compared to the international state of the art and to well-known perovskites with (pseudo)-cubic crystal structure, it seems that the specific reticular system of LiNbO3 is to be related to the stronger shape anisotropy of nanocrystals obtained under our synthesis conditions.; Communément appelé le « silicium de la photonique », le niobate de lithium (LiNbO3) sous forme nanométrique fait l’objet de ce travail. De tels nanocristaux, dits harmoniques en raison de leur structure cristalline non centrosymétrique et de leurs excellentes propriétés optiques non linéaires, peuvent être utilisés comme agents de contraste en imagerie biomédicale multiphotonique pour un meilleur diagnostic et un relargage ciblé d’agents thérapeutiques. La synthèse de nanocristaux de LiNbO3 en conditions solvothermales, à partir de précurseurs alcoxydes, est décrite avec une attention toute particulière à la compréhension fine des mécanismes réactionnels. À terme, cette compréhension a pour but de mieux contrôler les polydispersités de taille et de forme des nanocristaux en modifiant à souhait les vitesses de nucléation et de croissance. Pour les synthèses non aqueuses, l’eau n’étant ni ajoutée ni générée dans le milieu réactionnel, il est démontré que la décomposition thermique du précurseur ethoxide mixte choisi gouverne la cinétique de génération des monomères et conduit, dans ce cas, à la formation de nano-plaquettes. Un ajout contrôlé de glycols, comme le butane-1,4-diol et le pentane-1,5-diol, permet par contre de préparer des nanocristaux de forme quasi-sphérique avec une faible distribution en taille et forme en raison d’une meilleure stabilité des carbocations, favorisant ainsi une étape de nucléation plus courte et intense. Pour la voie hydrolytique, la variation du taux d’hydrolyse h conduit soit à des gels polymériques (h1) dont le traitement solvothermal produit des nanocristaux de faible et de forte polydispersité, respectivement. Par rapport à l’état de l’art international et aux pérovskites bien connues de structure cristalline (pseudo)-cubique, il semble que le système réticulaire propre à LiNbO3 est à relier à la plus forte anisotropie de forme des nanocristaux obtenus pour nos conditions de synthèse.

Commonly called the "silicon of photonics", lithium niobate (LiNbO3) at the nanoscale is the subject of this work. These so-called harmonic nanocrystals, due to their non-centrosymmetric crystal structure and excellent non-linear optical properties, can be used as contrast agents in multiphoton biomedical imaging for better diagnosis and targeted release of therapeutic agents. The synthesis of LiNbO3 nanocrystals under solvothermal conditions, from alkoxide precursors, is described with a special focus on the fine understanding of reaction mechanisms. Ultimately, this understanding aims to better control the nanocrystal size and shape polydispersity by modifying nucleation and growth rates as desired.For non-aqueous syntheses, since water is neither added nor generated in the reaction medium, it is shown that thermal decomposition of the chosen ethoxide precursor governs the formation kinetics of the monomers and leads, in this case, to the production of nano-platelets. On the other hand, a controlled addition of glycols, such as butane-1,4-diol and pentane-1,5-diol, makes it possible to prepare quasi-spherical nanocrystals with a smaller size and shape distribution due to a better carbocation stability, thus favoring a shorter and more intense nucleation step.For the hydrolytic route, the variation of the hydrolysis rate h leads either to polymeric gels (h1) whose solvothermal treatment produces nanocrystals of low and high polydispersity, respectively. Compared to the international state of the art and to well-known perovskites with (pseudo)-cubic crystal structure, it seems that the specific reticular system of LiNbO3 is to be related to the stronger shape anisotropy of nanocrystals obtained under our synthesis conditions., Communément appelé le « silicium de la photonique », le niobate de lithium (LiNbO3) sous forme nanométrique fait l’objet de ce travail. De tels nanocristaux, dits harmoniques en raison de leur structure cristalline non centrosymétrique et de leurs excellentes propriétés optiques non linéaires, peuvent être utilisés comme agents de contraste en imagerie biomédicale multiphotonique pour un meilleur diagnostic et un relargage ciblé d’agents thérapeutiques.La synthèse de nanocristaux de LiNbO3 en conditions solvothermales, à partir de précurseurs alcoxydes, est décrite avec une attention toute particulière à la compréhension fine des mécanismes réactionnels. À terme, cette compréhension a pour but de mieux contrôler les polydispersités de taille et de forme des nanocristaux en modifiant à souhait les vitesses de nucléation et de croissance.Pour les synthèses non aqueuses, l’eau n’étant ni ajoutée ni générée dans le milieu réactionnel, il est démontré que la décomposition thermique du précurseur ethoxide mixte choisi gouverne la cinétique de génération des monomères et conduit, dans ce cas, à la formation de nano-plaquettes. Un ajout contrôlé de glycols, comme le butane-1,4-diol et le pentane-1,5-diol, permet par contre de préparer des nanocristaux de forme quasi-sphérique avec une faible distribution en taille et forme en raison d’une meilleure stabilité des carbocations, favorisant ainsi une étape de nucléation plus courte et intense. Pour la voie hydrolytique, la variation du taux d’hydrolyse h conduit soit à des gels polymériques (h1) dont le traitement solvothermal produit des nanocristaux de faible et de forte polydispersité, respectivement. Par rapport à l’état de l’art international et aux pérovskites bien connues de structure cristalline (pseudo)-cubique, il semble que le système réticulaire propre à LiNbO3 est à relier à la plus forte anisotropie de forme des nanocristaux obtenus pour nos conditions de synthèse.

Harmonic nanocrystals with a non-centrosymmetric crystalline structure have nonlinearoptical properties that are particularly interesting for use as optical markers inbiomedical imaging.The Hyper-Rayleigh scattering technique currently used to quantify the secondharmonic response of nanoparticles in suspension has been extended in this work todetermine the third order non-linear susceptibility of different nanomaterials (BiFeO3,ZnO, KNbO3 and LiNbO3). Furthermore, the development of an experimental set-upbased on a wavelength-tunable source has allowed probing the non-linear opticalresonances of the 2nd order (for excitation between 700 nm and 1300 nm) of thesedifferent materials. The spectral response of WS2 nanosheets has also been studiedusing the same system. Finally, we have demonstrated the detection of fourthharmonic signals from a single BiFeO3 nanoparticle using a multiphotonicmicroscopy device combined with a Telecom laser source for future integration ofthese nanoparticles as frequency conversion elements for nanophotonics.; Les nanocristaux harmoniques de structure cristalline non centrosymétrique possèdentdes propriétés optiques non linéaires intéressantes notamment pour une utilisationcomme marqueurs optiques en imagerie biomédicale.La technique de diffusion Hyper-Rayleigh habituellement utilisée pour quantifier laréponse de deuxième harmonique de nanoparticules en suspension a été étendue dansce travail pour déterminer la susceptibilité non linéaire d’ordre 3 de différentsnanomatériaux (BiFeO3, ZnO, KNbO3 et LiNbO3). D’autre part, le développementd’un montage expérimental basé sur une source accordable en longueur d’onde apermis de sonder les résonances optiques non linéaires d’ordre 2 (pour une excitationcomprise entre 700 nm et 1300 nm) de ces différents matériaux. La réponse spectralede nanofeuillets de WS2 a également été étudiée à l’aide du même système. Enfin,nous avons démontré la détection de signaux de quatrième harmonique d’unenanoparticule unique de BiFeO3 à l’aide d’un dispositif de microscopiemultiphotonique associé à une source laser Telecom pour une future intégration deces nanoparticules comme éléments de conversion de fréquence pour lananophotonique.