Nonlinear Absorption Effect Research Articles

Research on Nonlinear Absorption Effect in KDP and 70%-DKDP Crystals

Nonlinear optical absorption effect in KDP and 70%-DKDP crystals, which were grown by the conventional temperature cooling method, was systematically studied using picosecond pulse laser excitation. Using open aperture Z-scan measurements, the dependence of nonlinear absorption effect on sample orientations (I, II, and z) as well as laser intensity was systematically measured at λ = 1064 and 532 nm. According to the experimental results, the nonlinear absorption effect at λ = 532 nm was confirmed, while at λ = 1064 nm no nonlinear absorption was observed for KDP and 70%-DKDP crystals. In addition, the optical absorption along I- and II-type affected by laser intensity was larger than that along the z-direction. The important nonlinear absorption coefficients β and χ I ( 3 ) (esu) measured along different orientations were exhibited in detail at wavelengths of 1064 nm and 532 nm. The results indicate that nonlinear absorption coefficients increase first and then decrease with the increment of laser intensity for KDP and 70%-DKDP crystals.

Construction and nonlinear optical characterization of CuO quantum dots doped Na2O–CaO–B2O3–SiO2 bulk glass

The spherical shape copper oxide (CuO) quantum dots (QDs) were successfully fabricated via copper basic calcium sodium borosilicate (Na2O–CaO–B2O3–SiO2) precursor obtained with a facile sol–gel technique. The microstructural analysis of doped QDs are systemically characterized, such as transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photo-electron spectroscopy. And the results reveal that the CuO QDs with the small size are well dispersed doped in sodium calcium borosilicate glass. Remarkably, the CuO glass materials exhibit the good third-order optical nonlinear susceptibility χ(3) (1.379 × 10−12 esu), which was investigated by femto-second Z-scan technique at the wavelength of 1550 nm, pulse duration of 50 fs, repetition rate of 50 MHz. The glass hybrids displayed a reverse saturable absorption and self-focusing refraction performance. And the mechanism to explain the third-order nonlinearity of CuO glass may be predominantly originated from the surface plasmon resonance effect, the quantum confinement effect and partly from the thermal effect. Besides, it is interesting that the glass hybrids have significant nonlinear absorption effects that endow the material to the potential value of the application of optical limiting device.

Laser induced optical and microscopic studies of salicylic acid influenced KH2PO4 crystal for photonic device applications

The present communication is aimed to explore the characteristic properties of salicylic acid (SA) doped potassium dihydrogen orthophosphate (KDOP) crystal. The single SA doped KDOP crystal with optimum dimension of 10 × 08 × 04 mm3 has been grown from solution by slow evaporation at ambient temperature. The single crystal X-ray diffraction analysis has been employed to determine the structure and cell parameters of grown crystal. The Z-scan studies have been carried out at 632.8 nm to ascertain the influential third-order non-linear optical (TONLO) nature of SA doped KDOP crystal. The Z-scan transmittance data have been used to determine the magnitude of TONLO susceptibility (χ3), absorption coefficient (β) and refractive index (n2) of SA doped KDOP crystal. For grown crystal, the surface damage due to exposure of high intensity of Nd:YAG laser operating at 1064 nm has been determined and found of order MW cm−2. The growth tendency, etch pattern and surface quality of grown SA doped KDOP crystal has been investigated by means of etching studies. The thermal response of grown crystal has been examined by differential thermal analysis employed in the range of 23–800°C. The hardness number of SA doped KDOP crystal has been investigated by means of Vickers microhardness study by applying different load ranging from 25 to 100 gm. The work hardening index and elastic stiffness coefficient have been evaluated using the hardness data. The nature of photoconductivity exhibited by grown crystal has been determined in voltage range of 10–100 V.Highlights• Z-scan analysis revealed negative non-linear refraction and reverse saturable absorption effect in SA-KDOP crystal.• The laser damage threshold of SA-KDOP crystal at 1064 nm is found to be 274·74 MWcm−2.• SA-KDOP crystal exhibited positive photoconducting nature within 10–100 V.• The dopant SA facilitated large enhancement in hardness parameters of KDOP crystal.• Etching and thermal analysis has been performed.

Evolution of diffraction and self-diffraction phenomena in thin films of Gelite Bloom/Hibiscus Sabdariffa

In this work, we present a study of non-linear optical response in thin films elaborated with Gelite Bloom and extract of Hibiscus Sabdariffa. Non-linear refraction and absorption effects were studied experimentally (Z-scan technique) and numerically, by considering the transmittance as non-linear absorption and refraction contribution. We observe large phase shifts to far field, and diffraction due to self-phase modulation of the sample. Diffraction and self-diffraction effects were observed as time function. The aim of studying non-linear optical properties in thin films is to eliminate thermal vortex effects that occur in liquids. This is desirable in applications such as non-linear phase contrast, optical limiting, optics switches, etc. Finally, we find good agreement between experimental and theoretical results.

Investigation on Third-Order Nonlinear Optical Properties of Four Transition Metal Complexes Thin Films by Z-Scan Technique

In this work, four new transition metal complexes, [Zn(PTP)]12(1,4-NDA)12·2H2O (1), [Zn(PTP) (4,4′-ODA)]2 (2), [Ni(PTP)(4,4′-ODA)]2 (3) and [Ni(FTP)]2Cl4 (4), have been synthesized by the reaction between a metal salt, Zn(II) or Ni(II), a rigid polycarboxylic ligand, naphthalene-1,4-dicarboxylic acid (1,4-NDA) or 4,4′-oxydibenzoic acid (4,4′-ODA) and a co-ligand, 4′-phenyl-2,2′:6′,2″-terpyridine (PTP) or 4′-(furan-2-yl)-2,2′:6′,2″-terpyridine (FTP). Complex 1 based on {Zn(PTP)(1,4-NDA)}n intertwined chains characterized by three different configurations which form a chiral chain structure. Complexes 2 and 3 present a structure made of discrete rings containing two central metal atoms. In Complex 4, two complex Ni(FTP)2+ ions are found to be connected with the μ2–Cl bridge to form a binuclear cluster. The third-order nonlinear optical properties of each complex thin film were evaluated by the Z-scan technique, indicating a strong third-order nonlinear reverse saturable absorption effect, with a high absorption coefficient β 3.89 × 10−6 for 1, 40.50 × 10−6 for 2, 4.76 × 10−6 for 3, and 1.37 × 10−6 m W−1 for 1, respectively. Interestingly, Complex 1 exhibits an effective nonlinear refractive effect with a refractive coefficient of 7.16 × 10−13 m2 W−1. The third-order NLO susceptibilities χ (3) of each complexes were calculated.

The synthesis of bimetallic gold plus nickel nanoparticles dispersed in a glass host and behavior-enhanced optical nonlinearities

A sol-gel synthetic route toward the fabrication of bimetallic gold plus nickel nanoparticles (NPs) in sodium borosilicate glasses is presented, with controlled atmosphere heat treatments. Characterizations of the as-obtained glasses indicate that when exposed to variable atmospheres of oxygen (O2) and oxygen (O2)-hydrogen (H2), randomly distributed Au/NiO NPs and Au/Ni NPs are produced in the glass host, respectively. Subsequently, the Z-Scan technique is conducted to examine their nonlinear optical response with femtosecond pulses. The two glasses show superior optical nonlinearities comparable to that of the glasses incorporated with Au NPs. For the glass dispersed with Au/NiO NPs, the enhancement of the third-order nonlinear response mainly depends on a contribution of a stronger nonlinear refraction response. However, the dominant contribution to improve optical nonlinearities of the glass doped with Au/Ni NPs is the more intense nonlinear absorption effect.

Graphene-Decorated Microfiber Photonic Device for Generation of Rogue Waves in a Fiber Laser

We reported on the rogue wave generation in a passively mode-locked fiber laser by utilizing a graphene-decorated microfiber photonic device (GMPD). The GMPD, which simultaneously possesses highly nonlinear and saturable absorption effects, provides the suitable condition for investigating rogue waves. With the proper pump power, the localized noise-like multi-pulse wave packet could be easily generated from the proposed fiber laser, which leads to generation of high-contrast fast intensity fluctuations of ultrashort pulse events, namely, rogue waves. Our findings indicate that the graphene-deposited microfiber waveguide structure indeed could be an excellent highly nonlinear photonic device for observing nonlinear dynamics such as rogue waves in optical systems.

The effects of α- and β-amino substituents of phthalocyanine on photophysical and nonlinear optical properties of graphene oxide-tetraamino zinc(II) phthalocyanine hybrids

Two kinds of metameric tetra-amino-phthalocyanine zinc (ZnTAPc) bearing peripherally and non-peripherally substituent groups connected to graphene oxide (GO) has been synthesized via covalent functionalized reaction. A series of characterizations including X-ray photoelectron spectroscopy, Fourier transform infrared spectra, Raman spectra, thermogravimetric analysis and ultraviolet–visible absorption confirm that the two kinds of ZnTAPc are grafted onto the GO nanosheets successfully. The fluorescence spectra show strong fluorescence quenching by the photo-induced electron transfer (PET) process between ZnTAPc moieties and GO nanosheets, and the possibility of the PET process has been further proved using the thermodynamic method. The nonlinear optical (NLO) properties of the two kinds of hybrid material were investigated using the Z-scan technique at the wavelength of 532 nm in the nanosecond scale. The GO-β-ZnTAPc hybrid possesses much stronger nonlinear absorption effect than GO-α-ZnTAPc hybrid, showing that the position of substituent have a significant influence on the NLO properties of aforementioned hybrids.

“Closer is Better and Two is Superior to One”: Third-Order Optical Nonlinearities of a Family of Porphyrin–Anderson Type Polyoxometalate Hybrid Compounds

A family of covalently bonded hybrid compounds composed of Anderson type polyoxometalate (POM) moiety and porphyrin moiety have been synthesized and thoroughly characterized. The compounds all show remarkable nonlinear reverse saturable absorption and self-defocusing effect at 532 nm with a pulse duration τ = 6 ns, rendering them promising candidate materials for device applications in photonics and optoelectronics. More importantly, it is found that the hybrid wherein POM is coupled covalently to porphyrin through shorter bridge has an NLO response superior to the hybrid wherein POM is bonded via longer bridge to porphyrin, and the hybrid having two porphyrins connected to POM shows more enhancement than the hybrid having single porphyrin fused to POM. Disclosure of the inherent structure–property relationship is expected to be instructive for exploration of new porphyrin-POM based NLO materials. Meantime, the hybrid compounds have optical-limiting thresholds lower than 1.0 J/cm2, implying their high pot...

Structure and third-order nonlinear optical properties of the two-dimensional CoII coordination polymer [Co(1,2-BIB)(PA)]n {1,2-BIB is 1,2-bis[(1H-imidazol-1-yl)methyl]benzene and H2PA is phthalic acid}.

The design of nonlinear optical (NLO) materials with large NLO responses has been a challenge for materials scientists and chemists. Recently, organic polymers have received attention regarding their NLO properties and fast nonlinear response, and clusters involving delocalized dπ-pπ systems and conjugated dπ-pπ systems are expected to be a new class of NLO materials. Metal-organic coordination polymers combine the advantages of the organic and inorganic species. Thus far, tuning the third-order NLO properties of these materials has been a significant challenge. A two-dimensional coordination polymer, namely poly[(μ-benzene-1,2-dicarboxylato-κ3O1,O1':O3){μ-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κ2N3:N3'}cobalt(II)], [Co(C8H4O4)(C14H14N4)]n, was synthesized by hydrothermal methods. In the structure, the CoII ion is pentacoordinated by two N atoms from two different 1,2-bis[(1H-imidazol-1-yl)methyl]benzene (1,2-BIB) ligands and three O atoms from two symmetry-related benzene-1,2-dicarboxylate (isophthalate, PA) anions. The pentacoordinated CoII ions are linked by PA ligands to form a chain structure parallel to the c axis. Adjacent chains are further connected by 1,2-BIB ligands to produce a two-dimensional layered structure. The compound exhibits strong third-order nonlinear absorption and nonlinear refraction effects as a thin film. The third-order susceptibility χ(3) is calculated to be 1.07 × 10-8 esu, which is much larger than the values found for pure inorganic semiconductors and some polymers.

Study on the highly transmitted Ag–In2O3/glass nanocomposite material: fabrication, microstructure and nonlinear absorption effects

We fabricated a highly transmitted Ag–In2O3/glass nanocomposite material through a sol–gel method plus a controlled gas. Microstructural analysis revealed that the Ag and In elements in the Ag–In2O3 nanostructure exist in two forms: crystalline Ag nanoparticles and non-crystalline In2O3. And the crystalline Ag nanoparticles show the small size, uniform distribution and good dispersion in the glass host, thus triggering the surface plasmon resonance (SPR) effect and the quantum confinement effect. Remarkably, the Ag–In2O3/glass nanocomposite material exhibits the high transmittance greater than 70% in almost the whole visible spectral range. Open-aperture Z-scan technique further showed a typical two-photon absorption effect in the Ag–In2O3/glass nanocomposite material, where the nonlinear absorption coefficient was determined to be ~1.1 × 10−9 cm W−1, and interestingly, the normalized transmittance decreased with increasing input fluence. The present results blaze a new path to develop the metal/glass nanocomposite materials with high transmittance, significant nonlinear absorption effects and potential optical limiting behavior. In addition, the mechanism on the nonlinear absorption effects were also discussed in this paper, such as the SPR effect, the quantum confinement effect, the thermal effects, the nonlinear scattering effect and the resonant nonlinear effect.

Effects of nonlinear absorption and third order dispersion on soliton propagation in optical fiber

In this work, we use the generalized nonlinear Schrödinger equation to study propagation of ultrashort optical pulses in the presence of self-phase modulation, nonlinear absorption and third-order dispersion. The combined effect of the third-order dispersion and nonlinear absorption on amplitude, center location and phase of the soliton has investigated by approximate analytical method. Full Text: PDF References Govind. P. Agrawal, Nonlinear Fiber Optics, Academic Press, San Diego (California), 2001. DirectLink Hasegawa. A, M. Matsumoto, Optical solitons in fibers, Springer-Verlag Berlin Heidelberg 2003. CrossRef G. Tsigaridas, I. Polyzos, V. Giannetas and P. Persephonis, "Compensation of nonlinear absorption in a soliton communication system", Chaos, Solitons & Fractals, Vol. 35, 2008, pp.151-160. CrossRef Haus H., "Optical-fiber solitons, their properties and uses", P. IEEE 81:970-83 (1993). CrossRef Chan VWS, Hall KL, Modiano E, Rauschenbach KA., "Architectures and technologies for high-speed optical data networks", J Lightwave Technol 16:2146-68 (1998). CrossRef Newhouse MA, Weldman DL, Hall DW, "Enhanced-nonlinearity single-mode lead silicate optical fiber", Opt Lett, vol.16, 1185 (1990). CrossRef Okuno T, Onishi M, Kashiwada T, Ishikawa S, Nishimura M., "Silica-based functional fibers with enhanced nonlinearity and their applications", IEEE J Sel Top Quant, Vol. 5, 1385(1999). CrossRef G. I. Stegeman, in Contemporary Nonlinear Optics, edited by G. P. Agrawal and R. W. Boyd (Academic, San Diego), 1992. M. A. Newhouse, D. L. weidman, and D. W. Hall, "Enhanced-nonlinearity single-mode lead silicate optical fiber", Opt. Lett. Vol,15, 1185 (1990). CrossRef M. A. Newhouse, in Proceedings of a Symposium on Optical Waveguide Materials, Boston, 1991. Dinh Xuan Khoa, Bui Dinh Thuan, "Influence of loss and high-order dispersion on soliton?s transmision in optical fibers", Communications in Physics, Vol.17, 17 ? 22 (2007). DirectLink

In situ measurement of the effective nonlinear absorption order in multiphoton photoresists

AbstractKnowledge of the order of the effective nonlinear absorption in multiphoton photoresists is a key element in the development of improved materials for multiphoton absorption polymerization (MAP). The direct measurement of this nonlinearity has proven challenging. A new technique called 2‐beam initiation threshold (2‐BIT) is presented that allows for the unambiguous, in situ measurement of the order of the effective nonlinear absorption using a simple optical arrangement that can be employed with virtually any MAP setup. This technique is benchmarked using three common commercial photoinitiators that have been used previously in MAP and one common dye that acts as a photoinitiator. The linear absorption spectrum is demonstrated to be a poor predictor of the effective order of nonlinear absorption at a given wavelength. Surprisingly, for two of these initiators the effective nonlinear absorption process is dominated by 3‐photon absorption in the 800 nm wavelength range, suggesting that 2‐BIT is a valuable means of identifying initiators that can improve the resolution of MAP. image

Bound Soliton Fiber Laser Mode-Locking Without Saturable Absorption Effect

Stable bound soliton laser mode-locking is experimentally demonstrated in an environmentally stable hybrid mode-locked Er-doped fiber laser without incorporating (equivalent) nonlinear saturable absorption effects. The laser has a sigma-type cavity and exhibits a higher threshold for single to bound soliton mode-locking state transition. A nonlinear eigenstate analysis based on the master equation model and the concept of steady-state lasing gain is developed to more physically explain the observed mode-locking state transition phenomena.

Second harmonic generation of Cosh-Gaussian laser beam in collisional plasma with nonlinear absorption

This paper investigates second harmonic generation (SHG) of an intense Cosh-Gaussian (ChG) laser beam propagating through a preformed underdense collisional plasma with nonlinear absorption. Nonuniform heating of plasma electrons takes place due to the nonuniform irradiance of intensity along the wavefront of laser beam. This nonuniform heating of plasma leads to the self-focusing of the laser beam and thus produces strong density gradients in the transverse direction. The density gradients so generated excite an electron plasma wave (EPW) at pump frequency that interacts with the pump beam to produce its second harmonics. To envision the propagation dynamics of the ChG laser beam, moment theory in Wentzel–Kramers–Brillouin (W.K.B) approximation has been invoked. The effects of nonlinear absorption on self-focusing of the laser beam as well as on the conversion efficiency of its second harmonics have been theoretically investigated.

Effect of the mismatch structure on crystal packing, physical properties and third-order nonlinearity of unsymmetrical twistacenes

A novel family of unsymmetrical twistacene analogues were synthesized in a palladium-promoted cross-coupling reaction and fully characterized, where five-membered ring was embedded into the main skeleton in these molecules. The formed all-carbon compounds appreciate a series of promising photophysical properties such as good thermal stability and photostability than that of acenes consisting of all six-membered rings. All of them emitted strong solution fluorescence covered a wide range from cyan to yellow. In addition, the nonlinear optical properties were further investigated through the top-hat Z-scan technique at 515 nm, which indicates that all of them presented excellent third-order nonlinear absorption effects.

A diffusive virus infection dynamic model with nonlinear functional response, absorption effect and chemotaxis

From a biological perspective, a diffusive virus infection dynamic model with nonlinear functional response, absorption effect and chemotaxis is proposed. In the model, the diffusion of virus consists of two parts, the random diffusion and the chemotactic movement. The chemotaxis flux of virus depends not only on their own density, but also on the density of infected cells, and the density gradient of infected cells. The well posedness of the proposed model is deeply investigated. For the proposed model, the linear stabilities of the infection-free steady state E0 and the infection steady state E* are extensively performed. We show that the threshold dynamics can be expressed by the basic reproduction number R0 of the model without chemotaxis. That is, the infection-free steady state E0 is globally asymptotically stable if R0 < 1, and the virus is uniformly persistent if R0 > 1. In addition, we use the cross iteration method and the Schauder’s fixed point theorem to prove the existence of travelling wave solutions connecting the infection-free steady state E0 and the infection steady state E* by constructing a pair of upper-lower solutions. At last, numerical simulations are presented to confirm theoretical findings.

Broadband Two-Photon Absorption Characteristics of Highly Photostable Fluorenyl-Dicyanoethylenylated [60]Fullerene Dyads.

We synthesized four C60-(light-harvesting antenna) dyads C60 (>CPAF-Cn) (n = 4, 9, 12, or 18) 1-Cn for the investigation of their broadband nonlinear absorption effect. Since we have previously demonstrated their high function as two-photon absorption (2PA) materials at 1000 nm, a different 2PA wavelength of 780 nm was applied in the study. The combined data taken at two different wavelength ranges substantiated the broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial π-conjugation between the C60 > cage and CPAF-Cn moieties, via endinitrile tautomeric resonance, giving a resonance state with enhanced molecular conjugation. This transient state could increase its 2PA and excited-state absorption at 800 nm. In addition, a trend of concentration-dependent 2PA cross-section (σ2 ) and excited-state absorption magnitude was detected showing a higher σ value at a lower concentration that was correlated to increasing molecular separation with less aggregation for dyads C60(>CPAF-C18) and C60(>CPAF-C9), as better 2PA and excited-state absorbers.

Optical and Nonlinear Optical Limiting Properties of AgNi Alloy Nanostructures

Silver-nickel alloy nanoparticles with varying size were synthesized by reducing the metal precursors chemically using a single-step solution-based synthesis route. The structural, optical, and nonlinear optical properties of the prepared samples were investigated. The synthesized samples having highly agglomerated, interconnected nature and found to exhibit dipole and multipole surface plasmon resonance related optical absorption bands. Nonlinear optical and optical limiting properties were investigated using a single beam open aperture z-scan technique with the use of 532 nm, 5-ns laser pulses. The nonlinearity observed was found to have contributions from saturable absorption (SA) and excited state absorption (ESA) related to free carriers. The effective nonlinear optical absorption was enhanced in AgNi alloy compared to pure Ag nanostructures.

Nonlinear optical properties of (1−x) CaFe2O4–xBaTiO3 composites

In this paper, we report nonlinear optical properties of a composite nanostructure with the general formula (1−x) CaFe2O4–(x) BaTiO3 (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) prepared by sol–gel and conventional solid-state reaction methods. Structural properties and chemical compositions of the samples were characterized using XRD and HRTEM. Basic optical constants, band gap energy and linear absorption coefficient were calculated through optical absorbance measurements. The nonlinear optical properties were investigated using the single-beam open aperture Z-scan technique. The obtained nonlinearity fits to Two-photon absorption process and all samples display high nonlinear absorption effect. The incorporation of BaTiO3 into CaFe2O4 systems show a significant improvement in the nonlinear optical properties. These composite that exhibit efficient optical limiting can have potential applications in photonic devices.