Three-photon Absorption Process Research Articles

Preparation and improved luminescent properties of Tb3+/Yb3+ co-doped Na2O–CaO–SiO2–Al2O3–ZnO–CaF2 transparent glass-ceramics

Transparent glass-ceramics containing CaF2 single-phase or CaF2/Ca5(PO4)3F two-phase were obtained by heat-treating the precursor glass. Compared with the precursor glass, the glass-ceramics containing CaF2 crystal with low phonon energy greatly enhance the emission intensity. Further research was conducted on the influence of various crystallization procedures on the luminescent properties of the glass-ceramic, and the procedure crystallized at 660 °C for 4 h was determined to be the optimal heat treatment. The SEM results indicate that the crystal size of the glass-ceramics is in the nanometer scale, which guarantees the possibility of its optical application. The three-photon absorption process of the Tb3+/Yb3+ co-doped glass-ceramics containing CaF2 single-phase was confirmed based on the up-conversion emission spectra excited at different power of 980 nm laser. The chromaticity coordinates of the Tb3+/Yb3+ co-doped glass-ceramic are located in the green region, indicating its potential applications in green lighting and other optical display devices.

Nonlinear optical properties of methyl green investigated by the femtosecond Z-scan technique

The third-order optical nonlinearities of methyl green in aqueous solution are studied by the Z-scan technique using a femtosecond laser at 800 nm. The valley shape in the open aperture measurements reveals the presence of reverse saturable absorption effect, which is ascribed to the three-photon absorption process. The closed aperture Z-scan traces demonstrate a negative sign for the nonlinear refractive coefficient, indicating the self-defocusing optical nonlinearity. Furthermore, the magnitudes of the nonlinear refractive index n 2, the three-photon absorption coefficient α 3, and the real part of the third-order nonlinear optical susceptibility Re χ (3) are determined and found to be linearly proportional to the dye concentration within the investigated range. Our results suggest that methyl green may be a hopeful candidate for applications in nonlinear optics.

Multiphoton Absorption in Gallium Nitride and Silicon Carbide Photodiodes: Applications for Single-Event Effects Tests

We report on the investigation of multiphoton absorption processes in gallium nitride and silicon carbide photodiodes. Up to three-photon absorption mechanisms were evidenced on both materials, thanks to a wavelength-tunable femtosecond laser chain. These results are applied to single event effect investigations on a commercial gallium nitride high electron mobility transistor. We could trigger single event transients by focusing the beam throughout the silicon substrate and collect charge that was photogenerated in the gallium nitride layer by a three-photon absorption process.

Nonlinear Optical Absorption in Nanoscale Films Revealed through Ultrafast Acoustics.

Herein we describe a novel spinning pump-probe photoacoustic technique developed to study nonlinear absorption in thin films. As a test case, an organic polycrystalline thin film of quinacridone, a well-known pigment, with a thickness in the tens of nanometers range, is excited by a femtosecond laser pulse which generates a time-domain Brillouin scattering signal. This signal is directly related to the strain wave launched from the film into the substrate and can be used to quantitatively extract the nonlinear optical absorption properties of the film itself. Quinacridone exhibits both quadratic and cubic laser fluence dependence regimes which we show to correspond to two- and three-photon absorption processes. This technique can be broadly applied to materials that are difficult or impossible to characterize with conventional transmittance-based measurements including materials at the nanoscale, prone to laser damage, with very weak nonlinear properties, opaque, or highly scattering.

Dynamics of Methyl Radical Formation Following 266 nm Dissociative Photoionization of Xylenes and Mesitylene.

The 266 nm dissociative photoionization of three xylene isomers and mesitylene leading to the formation of methyl radical was examined. The total translational energy distribution profiles [P(ET)] for the methyl radical were almost identical for all of the three isomers of xylene and mesitylene, while a substantial difference was observed for the corresponding P(ET) profile of the co-fragment produced by loss of one methyl group in m-xylene. This observation is attributed to the formation of the methyl radical from alternate channels induced by the probe. The P(ET) profiles were rationalized based on the dissociation of {sp2}C-C{sp3} bond in the cationic state, wherein the {sp2}C-C{sp3} bond dissociation energy is substantially lower relative to the neutral ground state. The dissociation in the cationic state follows a resonant three-photon absorption process, resulting in a maximum translational energy of about 1.6-1.8 eV for the photofragments in the center-of-mass frame. Fitting of the P(ET) profiles to empirical function reveals that the dynamics of {sp2}C-C{sp3} bond dissociation is insensitive to the position of substitution but marginally dependent on the number of methyl groups.

NaLaMo2O8:Yb3+, Er3+ transparent glass ceramics: Up-conversion luminescence and temperature sensitivity property

A novel transparent Yb3+/Er3+ co-doped NaLaMo2O8 glass ceramics (GCs) with borosilicate glass as the matrix were prepared via glass melting and subsequent controlled crystallization method, and the light transmission property, phase structure, microstructure and up-conversion (UC) performance were characterized by XRD, TEM, transmittance spectroscopy and photoluminescence spectrum. A decrease in the lattice parameter of NaLaMo2O8 in GC sample was verified by XRD Rietveld method, indicating the successful incorporation of Yb3+/Er3+ ions in the Na/La-site of NaLaMo2O8 phase. The UC emission intensity of transparent GCs was significantly enhanced compared to precursor glass. The green light emission in the UC is a three-photon absorption process. The 2.0Yb3+/0.1Er3+(mol%) co-doped GC sample shows the maximum absolute sensitivity of 1.406% K−1 at 473 K, which implies that the as-prepared GC exhibits potential application prospects in the field of optical temperature sensing.

Предельно короткие импульсы в оптически анизотропной среде с углеродными нанотрубками с учетом многофотонного поглощения

In this paper, we study the influence of multiphoton absorption on the propagation of electromagnetic waves in a nonlinear optical anisotropic medium with carbon nanotubes. The effective equation for the vector potential of the electromagnetic field of the pulse is obtained, taking into account the second component of the polarization of the field, as well as two- and three-photon absorption processes. The dependence of the components of the pulse field on the parameters of the problem is revealed.

Extremely short pulses in anisotropic optical media with carbon nanotubes taking into account multiphoton absorption

In this paper, we study the influence of multiphoton absorption on the propagation of electromagnetic waves in a nonlinear optical anisotropic medium with carbon nanotubes. The effective equation for the vector potential of the electromagnetic field of the pulse is obtained, taking into account the second component of the polarization of the field, as well as two- and three-photon absorption processes. The dependence of the components of the pulse field on the parameters of the problem is revealed. Keywords: optical anisotropy, extremely short pulse, multiphoton absorption.

Color tunable up-conversion luminescence characteristics of Yb3+-Er3+-Tm3+ tri-doped fluorosilicate glass potentially used in WLED field

A series of Yb3+-Er3+-Tm3+ tri-doped fluorosilicate glasses with different molar compositions were fabricated by a conventional melt-quenching method. The amorphous nature of glasses was confirmed by XRD. The structure of the glass network was characterized by FTIR and Raman scattering spectra. The absorption spectra were measured by a UV–vis–NIR spectrophotometer. Under the excitation of a 980 nm laser, as-prepared glass can emit intense red, green, and blue light in the emission spectra. And the warm-white emission (0.3569, 0.3953) can be generated at the glass sample SACF-Tm0.40. Finally, according to the up-conversion emission spectra recorded under 980 nm laser with different pump power conditions, a three-photon absorption process in the glass sample SACF-Tm0.50 was determined. And the energy transfer process in Yb3+-Er3+-Tm3+ tri-doped up-conversion luminescence system was discussed in detail.

Nonlinear optical effects in a nucleus

Intense laser technologies generate light with unprecedented and growing intensities. The possibility emerges that a nucleus responds nonlinearly to an intense light field, pointing to an emerging research area of nuclear nonlinear optics. Here we consider two-photon and three-photon absorption (with subsequent disintegration) processes of the deuteron, the simplest and the most fundamental nontrivial nucleus, as prototypes of nuclear nonlinear optical effects. Novel observable effects are predicted. Two-photon and three-photon absorptions are shown to lead to remarkably different angular distributions compared to one-photon absorption. Absorption rates are calculated supporting the feasibility of near-future experimental realization. This work paves a way to the emerging field of nuclear nonlinear optics.

Optical nonlinearities in chemically synthesized and femtosecond laser fabricated gold nanoparticle colloidal solutions

Gold nanoparticles prepared by two different methodologies, wet-chemical- citrate reduction synthesis and femtosecond laser ablation, are studied for optical nonlinearities. Femtosecond laser pulses at 800 nm wavelength are employed to study the optical nonlinear refraction and absorption through the Z-scan technique, up to 23.37 GW/cm2 laser intensities. Here we demonstrate the distinct crossovers of nonlinear absorption, from varieties of nonlinear absorption mechanisms, saturation of linear absorption, reverse saturation of absorption. The reverse saturation of absorption is primarily contributed by an initial two-photon absorption followed by three-photon absorption process. We could observe that in laser-ablated gold nanoparticles, the transition from saturable to reverse saturable absorption takes place at a lower excitation threshold compared to that in chemically produced samples. The nonlinear refraction data depicted a pronounced asymmetry for chemically synthesized samples, which could possibly be due to the dominance of absorption phenomenon. We observed that nonlinear refractive index of chemically produced samples is higher by one order of magnitude compared to those produced by laser ablation. An appealing application in optical limiting is studied, and we see that the laser-produced samples, due to their strong nonlinear absorption, serve as a suitable choice for the optical limiting application. This study provides an insight into the selection of synthesis method towards their optimized utilization in nonlinear optical domain given that we achieve particle size tunability in the two methods.

Multi-photon fluorescence microscopy imaging of mitochondria in living cells excited by Yb-doped femtosecond fiber laser utilizing two- and three-photon competitive absorption

By employing an Yb-doped femtosecond fiber laser oscillating at 1030 nm, multi-photon fluorescence microscopy imaging was demonstrated, utilizing competitive two- and three-photon absorption processes for excitation of the fluorescence probes. Competitive two- and three-photon absorptions occurred for all six of the fluorescence probes employed. The mitochondria of human embryonic kidney 293 cells were stained with the probes, and multi-photon fluorescence images were obtained in all cases. The brightest multi-photon fluorescence image was obtained when employing the probe compound possessing the longest cut-off wavelength. This can be attributed to the larger contribution of two-photon absorption to the competitive excitation process. Thus, by utilizing competitive two- and three-photon absorption processes, multi-photon fluorescence images can be acquired using Yb-doped femtosecond fiber laser excitation with a variety of probes.

Effect of relative position of donor and acceptor groups on linear and non-linear optical properties of quinoline system

Quinoline ring although extensively used in designing materials with non-linear optical (NLO) properties, the study of the effect of relative position of various electron-donor and electron-acceptor groups on these properties is still missing. Herein, we present a theoretical analysis of variation of various properties such as polarizability (α), static-hyperpolarizability (β), and one-, two-, and three-photon absorption processes with the relative positions of donor and acceptor groups in substituted quinoline ring using time-dependent density functional response theory. The observed variations in two- and three-photon transition strengths have also been analysed using few-state models.

Synthesis and characterization of optical properties of soft and hard Er3+-doped (K Na)NbO3 piezophotonic ceramics

Real-time tuning of photoluminescence properties are highly desirable for potential applications. Thus, one proposed approach is to tune the photoluminescence emissions by applying an external electric field. However, in order to switch the ferroelectric polarization, high quality bulk ceramics is demanded. In this work, soft and hard Er3+-doped (K,Na)NbO3 piezophotonic ceramics were prepared by the conventional route and their microstructural, structural and up-conversion emission properties were investigated. Dense and free from secondary phases ceramics were successfully produced. The photoluminescence spectra, in the visible range, were characterized as a function of the pumping power. For the soft composition, a remarkable green shift was verified with increasing the laser power. It was supposed that the excited state absorption, involving a three-photon absorption process, was involved in the 4S3/2→4I15/2 transition. For the hard composition, the two-photon absorption process was dominant and the presence of complex defects reduced significantly the 4F9/2→4I15/2 transition.

Effect of F/O ratio on up-conversion and down-conversion luminescence properties of Er3+/Yb3+ co-doped SiO2–Al2O3–AlF3-Gd2O3–Na2O glass

Er3+/Yb3+ co-doped SiO2–Al2O3–AlF3-Gd2O3–Na2O glass with different F/O ratios were prepared. The effect of F/O ratio on the structure and optical properties of the glasses was investigated. The amorphous nature of the glasses was determined by XRD, and the glass transition temperature (Tg) and the crystallization peak temperature (Tc) were obtained from the DSC curves. The change in the structure of the glass network was analyzed by infrared spectroscopy. The density and absorption spectra of the bulk glass was also investigated. The excitation spectrum, emission spectrum and 4S3/2 level fluorescence lifetime of Er3+ ions in the glasses were tested by a Xenon lamp with adjustable wavelength. The up-conversion luminescence spectrum of Er3+ ions was measured under excitation of a 980 nm laser. The results show that the green (2H11/2, 4S3/2) and red (4F9/2) up-conversion luminescence intensity is the highest when the F/O ratio is 0.214. According to the variation law of up-conversion luminescence intensity and pump power, it is confirmed that the up-conversion green (2H11/2 → 4I15/2, 4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) light of Er3+ ions are the three-photon absorption process based on excited state absorption (ESA) and energy transfer up-conversion (ETU) mechanism. Finally, energy transfer transitions between Er3+ and Yb3+ are also analyzed. The CIE chromaticity coordinates were calculated from the emission spectrum obtained at two different excitation wavelengths of 378 nm and 980 nm.

Synthesis and luminescence properties of Yb3+, Tm3+ and Ho3+ co-doped SrGd2(WO4)2(MoO4)2 nano-crystal

Novel up-conversion luminescent SrGd2(WO4)2(MoO4)2: Yb3+/Tm3+/Ho3+ nano-crystals were synthesized by hydrothermal method. The composition ratio of rare earth had been investigated. It indicated that when CYb3+ = 10 mol% and CYb3+/CTm3+/CHo3+ = 10:1.5:2, the emission intensities were the highest. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and up-conversion luminescence spectra were used to characterize SrGd2(WO4)2(MoO4)2: Yb3+/Tm3+/Ho3+ nano-crystals and they showed that the sample had high degree of crystallinity, the sample was tetragonal system, and the grain size of the sample was about 56 nm. Three emission peaks, including blue emission peak, green emission peak and red emission peak were observed at 477, 543 and 651 nm corresponding to 1G4 → 3H6 and 1G4 → 3F4 transitions of Tm3+, 5F4 → 5I8 and 5F5 → 5I8 transitions of Ho3+ respectively. All the emission peaks were observed by excitation of 980 nm semiconductor laser. The relationship between up-conversion intensity and excitation power revealed that blue emission at 477 nm was a three-photon absorption process, green emission at 543 nm and red emission at 651 nm was a two-photon absorption process. The quantum yields of the sample were near 3.2%.

Quantum interference control of localized carrier distributions in the Brillouin zone

Using transition-metal dichalcogenides as an example, we show that the quantum interference arising in two- and three-photon absorption processes can lead to controllable, highly localized carrier distributions in the Brillouin zone. We contrast this with the previously studied one- and two-photon absorption, and find qualitatively different features, including changes in the relevance of interband and intraband processes according to the excitation energy. Thus, the distribution of excitations arising under certain circumstances in two- and three-photon absorption can facilitate the study of far-from-equilibrium states that are initially well localized in crystal momentum space.

Several Orders-of-Magnitude Enhancement of Multiphoton Absorption Property for CsPbX3 Perovskite Quantum Dots by Manipulating Halide Stoichiometry

Two-photon absorption (2PA) and three-photon absorption (3PA) processes feature many technological applications for fluorescence microscopy, photodynamic therapy, optical data storage, and so on, Herein, we reveal that the giant 2PA and 3PA properties for all-inorganic CsPbX3 (X = Cl, Br, I, and mixed Cl/Br and Br/I) perovskite quantum dots (PQDs) can be enhanced several orders of magnitude, respectively, by simply changing the halide stoichiometry at the X site. Notably, reported data show excellent 2PA and 3PA properties for CsPbI3 (σ2 ∼ 2.1 × 106 GM and σ3 ∼ 1.1 × 10–73 cm8 s3/photon3), which is 2–4 orders of magnitude higher than those of conventional red-emitting QDs and 5–7 orders of magnitude higher than well documented organic molecules. Experimental results show multiphoton absorption (MPA) cross sections can be adjusted 2–3 orders of magnitude by band gap engineering in a predictable manner, via increasing the Pauling electronegativity of the halide. Two-photon luminescence imaging data show tha...

Characterization of nonlinear optical crystal absorption

A simplified absolute calibration for the photothermal laser-induced deflection technique is introduced and applied to characterize different nonlinear optical crystals at common diode pumped solid state laser wavelengths. In particular, intensity-dependent absorption measurements at 355 nm are performed to investigate the nonlinear absorption in lithium triborate crystals. From the results, it is verified that at least to a certain extent the nonlinear absorption is related to impurities or defects, i.e., to sequential three-photon absorption in addition to a potential intrinsic three-photon absorption process.

Phase control algorithms and filamentation of ultrashort laser pulses in a scattering medium

The scattering nature of biological systems restricts the non-linear propagation of coherent light in media of biological interest. Using a spatial phase shaping technique, we optimize the filamentation of femtosecond laser pulses in an ethanol solution containing a fluorescent dye, while the laser beam has first traveled through 1 cm of scattering aqueous solution. Following three-photon absorption process, the fluorescence signal of the Coumarin 440 dye is used as a control parameter by genetic and partitioning algorithms. Applied to the incident wavefront, the partitioning algorithm successfully enhances the dye fluorescence signal in a medium with a scattering coefficient ( $$\mu _{\text {s}}$$ ) varying from 1.24 to $$3.71\hbox { cm}^{-1}$$ and gives rise to the production of a single laser filament several millimeters inside the observation cell that contains an ethanol solution. Interestingly, the optimal enhancement for the highest scattering medium is obtained with the partitioning algorithm at the lowest resolution. On the other hand, no significant enhancement is obtained when applying the genetic algorithm.