Optical Limiting Devices Research Articles

Optical nonlinear properties of a new polyamide from crystal violet terephthalate

In this study, the nonlinear optical properties of a new polymer poly crystal violet terephthalate (PCVT) as a solution and a thin film with different concentrations of 0.2, 0.6, and 1 mM and input power were investigated by using Z-scan technique at 532 nm CW laser beam wavelength. The negative nonlinear refractive index n 2 as well as reverse saturable and saturable absorption β of the solution and film PCVT samples were determined. Figures of merit were also determined. In comparison with the Z-scan results, a self-diffraction pattern setup was used to measure nonlinear refractive index. Results showed a significant laser power dependence of the number of far-field diffraction rings with power and concentration, consistent with the Z-scan data. The PCVT sample exhibited good optical limiting behavior. Hence, PCVT has important nonlinear properties, and its figures of merit can be optimized by adjusting the PCVT concentration and input power. PCVT is a promising candidate for the design of optical photonic switching and optical limiter devices.

Effect of morphology modulation and interface engineering of SnS-MoS2 heterojunction on nonlinear optical response

MoS2 base films with different morphologies were prepared by modulating the magnetron sputtering parameters, and the base films were used to induce the growth of SnS with different structures, forming columnar and worm-like SnS-MoS2 heterojunctions, which were found to have excellent nonlinear absorption properties and their properties could be modulated by the morphology of the films by Z-scanning tests. The tunable morphology and crystalline quality of the films were characterized using scanning electron microscopy, atomic force microscopy and X-ray diffraction techniques and explained using the Stranski-Krastanow growth mechanism. The Raman spectrum of the heterojunction shows the A1g vibrational peak at 320 cm−1 and the appearance of Sn4+ in the X-ray photoelectron spectroscopy confirms the existence of S-Sn-S charge transfer channels between the interfaces. The fine spectra of all the elements in the X-ray photoelectron spectroscopy data as well as the characteristic absorption peaks in the absorption spectra confirm the formation of heterojunctions, and the constructed heterojunctions are determined to be type-II heterojunctions using the method of the core energy level. Heterojunction was determined to be a type-II heterojunction by using the core energy level method. The photoluminescence peak quenching of the heterojunction indicates that there is a process of charge transfer between the interfaces, and the type-II heterostructure of SnS-MoS2 makes the nonlinear absorption performance in the 800 nm band regulated by the morphology of the material. The nonlinear optical absorption coefficient is two orders of magnitude higher than that of the pure materials, and the nonlinear absorption performance of the worm-like SnS-MoS2 heterojunction is superior to that of the columnar SnS-MoS2 heterojunction, which is attributed to the larger interfacial contact area, the better crystalline quality, and the more efficient carrier interfacial transport capability. These tunable type-II SnS-MoS2 heterojunctions with ultrafast nonlinear optical absorption have a positive impact on practical applications such as optical limiter devices and all-optical switching devices.

Femtosecond nonlinear optical properties of Ti-doped In2Te3 thin films grown by magnetron co-sputtering

Herein, we successfully prepared Ti-doped In2Te3 and pure In2Te3 films by magnetron co-sputtering at room temperature. The film structure was measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS), while the linear optical constant of the films was measured using a spectroscopic ellipsometer (SE). The nonlinear optical properties of the films were examined using the Z-scan technique, wherein the samples were irradiated with 140 fs laser pulses at a wavelength of 800 nm and a repetition rate of 80 MHz, with an input intensity of 1.2GW/cm2. Ti incorporation led to decreased crystallinity and a reduction (redshift) in the optical bandgap (E g ). All films exhibit reverse saturation absorption (RSA) and self-focusing effect. A ninefold increase in the nonlinear refractive index (n2) and a fourfold increase in the nonlinear absorption coefficient (β) were observed for the Ti-doped S40 sample in comparison to the pure S0 sample. Adjusting the phase transition between amorphous and crystalline states in Ti-doped In2Te3 films further modulated their nonlinear optical properties. The optical limiting (OL) behavior of pure In2Te3 and Ti-doped In2Te3 thin films was investigated, and the results demonstrated that Ti-doped In2Te3 films show great promise as optical limiter devices in nonlinear photonics.

Effect of thickness on nonlinear optical properties of EZO thin films

In the present work, the effect of thickness on the nonlinear optical properties of Erbium-doped zinc oxide (EZO) films has been investigated. Erbium-doped zinc oxide (EZO-doping concentration of 0.4 wt%) ‘thin films’ of variable thickness were prepared by a spin coating method. The film thickness varied from 92–365 nm. EZO (0.4 wt%) samples were analyzed using Scanning Electron Microscopy (SEM), UV–vis-NIR spectroscopy, and x-ray diffraction (XRD). The z-scan method was applied to measure non-linearity for closed and open aperture configurations. The deposited films were found to have a significant growth orientation along the plane of (002). The deposited films satisfy two-photon absorption as indicated by the minus sign of n2. The values of third-order nonlinear optical susceptibility for the EZO (0.4 wt%) thin film sample were found in the range of 10–6 esu. The Erbium-doped ZnO (0.4 wt%) sample exhibited the best nonlinear behavior at a thickness of 280 nm (β = 8.90 × 10–6 cm W−1, n2 = −5.29 × 10–5 esu, (3) = 14.7 × 10–6 esu). The samples under investigation should pave the path for designing high-order optical limiter devices.

Bi/Ti3C2Tx composites: Synthesis and enhanced nonlinear optical and electrochemical properties

The Bi/Ti3C2Tx composites were synthesized by a hydrothermal method. Then the Bi/Ti3C2Tx powder was dispersed into methyl methacrylate (MMA) to fabricate the (Bi/Ti3C2Tx)2–6/polymethyl methacrylate (PMMA) organic glasses. The crystalline structure and phase of the Bi/Ti3C2Tx were measured by the X-ray diffraction. The photoluminescence (PL) spectra and the electrochemical impedance spectra (EIS) of the Bi/Ti3C2Tx were measured to prove the enhanced optical and electrical properties. The nonlinear optical (NLO) properties of the (Bi/Ti3C2Tx)2–6/PMMA organic glasses were investigated by the Z-scan technique. The (Bi/Ti3C2Tx)2–6/PMMA organic glasses exhibit the reverse saturable absorption (RSA) and self-defocusing effects. Compared to the (Bi)2/PMMA and (Ti3C2Tx)2/PMMA organic glasses, the (Bi/Ti3C2Tx)2–6/PMMA organic glasses exhibit the enhanced NLO properties. Among three different amount Bi/Ti3C2Tx/PMMA organic glasses, (Bi/Ti3C2Tx)4/PMMA organic glass exhibits the strongest RSA and self-defocusing effects with βeff = (6.34 ± 1.90)× 102 cm·GW−1 and γ = (–3.52 ± 0.07)× 10−4 cm2·GW−1. The enhanced RSA and self-defocusing effect of the (Bi/Ti3C2Tx)2–6/PMMA organic glasses make them exhibit the excellent optical limiting (OL) performance. In addition, the Bi/Ti3C2Tx composites show excellent electrochemical performance as an electrode material for energy storage systems. The resultant Bi/Ti3C2Tx electrode yields a high specific capacity of 68.5 mAh·g−1 at a current density of 1 A·g−1, which is approximately 4.2 and 6.1 times than those of the Bi and Ti3C2Tx electrodes, respectively. The experimental results exhibit the Bi/Ti3C2Tx is highly promising for energy storage and OL devices.

Synthesis and Properties of New 3-Heterylamino-Substituted 9-Nitrobenzanthrone Derivatives

In the present study, new fluorophores based on disubstituted benzanthrone derivatives were designed starting from 9-nitro-3-bromobenzanthrone with nucleophilic substitution of the bromine atom with some secondary cyclic amines. It has been found that this reaction is positively affected by the presence of a nitro group in comparison with 3-bromobenzanthrone. The new compounds exhibit intense absorption and pronounced luminescent properties in various organic solvents. In this regard, their photophysical properties were evaluated with an experimental study of the solvatochromic behavior of the obtained compounds in various solvents. It has recently been found that the addition of an electron-withdrawing nitro group to the benzanthrone core increases its first- and second-order hyperpolarizability. Such dyes can be used in the fabrication of optical limiter devices. Therefore, the developed fluorescent molecules have a potential prospect for extensive application in optoelectronics.

An experimental and DFT investigations of fused ring anthracenyl chalcones with effective modification in acceptor moiety: Nonlinear optical and optical limiting response

AbstractThe significance of the anthracene moiety on nonlinear optical (NLO) characteristics is thoroughly examined. The presence of strong electron donor and acceptor groups, large and prolonged conjugation transfer axis, amplifies the push–pull action and increases NLO responses. The values of χ3 obtained for AC derivatives are considerably larger (10−3 esu), indicating that they accurately reflect NLO reactions. According to the optical limiting (OL) investigation, AC has a strong limiting behavior with action beginning at 1.6 KW/cm2. The relationship between transmittance and intensity has demonstrated their potential use in OL applications. Nonlinear optical studies show that all conjugated anthracene chalcones are potential materials for OL devices.

Influence of nitro group on solvatochromism, nonlinear optical properties of 3-morpholinobenzanthrone: Experimental and theoretical study

We report the synthesis of 3-morpholino-9-nitrobenzanthrone (NMB) dye. By using FT-IR, 1H NMR, and X-ray crystallography, we characterized the molecular structure of the synthesized dye. The structural features of the dye were compared to those of an identical dye without nitro substituents. The push pull kind of benzanthrone dye (NMB) was examined for solvent-dependent photophysical properties. NMB exhibits a large Stokes shift. The polarity plots indicate that hydrogen-bonding interactions are influential in most of the solvents. Detailed structural analysis as well as one-photon absorption and emission process was computationally investigated for both the molecules. NMB exhibits significant two photon absorption (TPA) activity at various electron transitions ranging from visible to NIR regions. Further, Nonlinear absorption coefficient was calculated for the dye samples from the open aperture Z-scan data. The nonlinear absorption coefficient values were obtained for the dye samples for input laser pulse energies ranging from 5 to 20 µJ. The results decipher that these dye samples are prospective contenders for the fabrication of optical limiter devices. Nitro substituents at the active site enhance charge transfer, thereby enhancing the NLO response.

Strong interfacial interactions of ZnS/Cu-TCPP hybrids contribute to excellent nonlinear optical absorption

In recent years, the research and development of optoelectronic devices based on metal-organic frameworks (MOFs) have increasingly triggered the interest and attention of researchers. However, their nonlinear optical (NLO) properties are in urgent need of improvement. Herein, we first report a method to improve the NLO response of MOFs by decorating ZnS nanoparticles. The NLO response of the hybrid is found to be much higher than that of pure MOFs and ZnS by the Z-scan technique. At higher incident intensities, the hybrids exhibit a giant optical limiting (OL) response with OL threshold as low as 2.82 × 10−7 J/cm2, which is better than almost all organic and inorganic materials reported in the literature so far, demonstrating the great value of hybrids for OL devices. As revealed by XPS characterizations, transient absorption (TA) spectroscopy, and DFT calculations, the strong interfacial interaction between ZnS nanodots and Cu-TCPP nanosheets can effectively promote the charge transfer process between them and significantly inhibit the recombination of photogenerated charge carriers, thus achieving a substantial enhancement of the NLO response. The simple preparation method and extremely low OL threshold suggest that this MOF-based hybrids have great potential for application in OL photonic devices.

All-Organic Composite Films for High Flexibility and Giant Nonlinear Optical Limiting Responses.

Given the substantial π-electron delocalization observed in 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST), a high third-order nonlinear optical response can be expected that might manifest itself in various ways for potential applications. To probe the possibility and assess its potential, all-organic DAST-polymethyl methacrylate (PMMA) composite films were prepared by a simple solution casting method, and their nonlinear absorption performances were measured by an open-aperture Z-scan system. The results reveal that under irradiation by a 380 fs laser pulse at 520 nm or a 6 ns laser pulse at 532 nm, the DAST-PMMA composite films with a DAST concentration of 0.125 wt % exhibit similar giant optical limiting (OL) responses with OL threshold of 7.84 or 0.37 GW cm-2, both superior to those of most organic and inorganic OL materials measured under similar conditions. These all-organic composite films show high flexibility, and interestingly, their OL responses can remain stable even after exposure to air for 3 months. The superior OL behaviors of such materials in the femtosecond and nanosecond regimes are attributed to the two-photon absorption and the combination of two-photon absorption and excited-state absorption, respectively. The simple preparation, high flexibility, giant OL responses, and excellent environmental stability suggest that such novel all-organic composite films hold great potential for applications in flexible OL devices.

The role of defects in the nonlinear optical absorption behavior of pristine and Co-doped V2O5 layered 2D nanostructures

V2O5 nanostructures doped with 1% Co have been successfully synthesized by simple hydrothermal method. Structural and morphological aspects, vibrational spectra and optical properties (linear and nonlinear) of pristine as well as Co-doped V2O5 (V2O5:Co) nanoparticles are investigated. X-ray diffraction patterns indicate that both V2O5 and Co doped V2O5 are stabilized in an orthorhombic structure. Energy band gaps measured using the Tauc plot give 2.24 eV for V2O5 and 2.16 eV for Co doped V2O5. When excited using 5 ns laser pulses at 532 nm in the open aperture Z-scan configuration, pristine as well as Co-doped V2O5 nanoparticles are found to show excellent nonlinear absorption, which arises from strong reverse saturable absorption occurring in the sample at this wavelength. The corresponding effective two-photon absorption coefficients are in the range of 10−11 to 10−12 m/W, and effective three-photon absorption coefficients are in the range of 10−22 to 10−23 m3/W2. When excited at the same wavelength using a continuous wave laser beam, the effective two-photon absorption coefficient gets enhanced to 10−6 m/W. These results confirm the suitability of V2O5 and Co-doped V2O5 nanoparticles for the fabrication of optical limiter devices for the protection of human eyes and sensitive optical detectors from hazardous laser radiation.

Enhanced third-order nonlinear optical properties of methyl orange dye-doped potassium penta borate octa hydrate (MOPPB) single crystals using CW diode laser for optical limiting applications

We report pure potassium penta borate octa hydrate (PPB) and methyl orange dye-doped potassium penta borate octa hydrate (MOPPB) for optical limiting applications. The crystals were grown by slow evaporation solution growth technique at ambient conditions. The single crystal X-ray diffraction (SXRD) evinces the orthorhombic class of the pristine and MOPPB crystals. Formation of PPB and incorporation of MO dye in PPB was confirmed through Fourier transform infrared (FTIR) study. Calculated hardness number and stiffness constant with Vicker’s Micro hardness study portrays the soft nature of the title crystals. The decrease in bandgap of MOPPB is due to the additional energy levels introduced between the valence band and conduction band which in turn increases the net polarizability of the crystal. Relative second harmonic generation (SHG) efficiency of pure PPB and MOPPB is 0.45 times and 0.40 times that of SHG output of KDP. Z-scan studies shows that both crystals show reverse saturable absorption (RSA) ascribed due to two-photon absorption (TPA) process. MOPPB [β = 1.68 × 10–5 m/W, n2 = 10.2 × 10–12 m2/W, χ(3) = 3.5 × 10–9 m2/V2] possess higher NLO coefficients than pure PPB [β = 0.98 × 10–5 m/W, n2 = 4.62 × 10–12 m2/W, χ(3) = 6.1 × 10–9 m2/V2] which assured the superiority of azo dye incorporation in PPB crystals. Pristine and MOPPB crystals depict the optical limiting (OL) behavior under continuous wave (CW) diode laser irradiation at 785 nm. Thus, the linear and nonlinear properties bestow the MOPPB single crystal as a versed material for OL devices used for the safeguard of optical components from laser damage.

Measurements of Linear and Nonlinear Optical Properties for Iraqi Heavy Crude Oil Samples

In this work, linear and nonlinear optical properties of two types of Iraqi heavy crude oil extracted from fields in southern Iraq were determined. The nonlinear optical properties were measured utilizing Z-scan technology with He-Ne laser at 632.8 nm. It was found that nonlinear refractive index (NLR) values for the Basra and Kut heavy crude oil samples are 6.34381×10-4 and 8.25108×10-4 cm2/mW, respectively, while those for the nonlinear absorption coefficient (NLA) are 2.68942×10-5 and 2.58874×10-5 , respectively. These results showed that the two samples with linear and nonlinear optical properties can be used in optics field applications as optical limiter devices at a wavelength of 632.8 nm.

Optical limiting behavior of the natural dye extract from Indigofera Tinctoria leaves

In this work, we extract the natural dye ingredient found in Indigofera Tinctoria leaves, and investigate its nonlinear optical absorption by employing the Z-scan technique. The dye is extracted from Indigo powder which is commercially available for hair coloring applications. The powder, which is made by grinding Indigofera Tinctoria leaves into fine particles, is mixed with water, sonicated, centrifuged and filtered to give an optically clear extract. Linear absorption of the extract is measured in the visible spectral region using a spectrophotometer. Nonlinear absorption in the green spectral region is measured using 5 ns (5 × 10−9 s), 532 nm laser pulses obtained from a frequency-doubled Nd:YAG laser. The Indigofera Tinctoria dye is found to show excellent nonlinear absorption, which arises from strong reverse saturable absorption occurring in the sample at this wavelength. The third order nonlinear absorption coefficient, which is obtained by numerically fitting the Z-scan data to the nonlinear transmission equation, has a high value in the order of 10−10 m/W. This high nonlinear absorption, which is in the same range as that of materials such as graphene oxide, leads to an excellent optical limiting behavior, making Indigofera Tinctoria a potential candidate for fabricating optical limiter devices for eye and sensor protection.

Optical limiting phenomenon study in oils of vegetable origin

The optical limiting effect was analyzed in two oils of vegetable origin, extra virgin olive oil and virgin avocado oil; which are materials that have a large amount of organic components and excellent physicochemical characteristics. In multiple works, organic materials have been shown to be effective as optical limiting devices, presenting a good response in materials that show two-photon absorption and saturable absorption. On the other hand, between the two configurations in which the optical limiting phenomenon can be analyzed (dispersion and transmission), the optical limiting study by transmission was carried out for both oils, where olive oil manifested a more limited region wide compared to avocado oil. Nevertheless, avocado oil showed saturation power and a lower limiting threshold. Important characteristics in the manufacture and search for materials used in optical limitation devices.

Experimental dispersion of the third-order optical susceptibility of graphene oxide

We experimentally determined the dispersion of third-order optical susceptibility χ(3) of graphene oxide (GO) in the visible region (450 - 750 nm) by combining spectroscopic ellipsometry and ultrafast pump and probe spectroscopy in the femtosecond regime. In order to mitigate the damage of wide-spectrum laser to photonic devices, GO has become a promising material for optical limiting (OL) devices. However, there is no report about the χ(3) dispersion of GO, which is a complex quantity that directly corresponds to nonlinear refraction and absorption and is a crucial parameter for the manipulation and application of its OL properties. Here, we identified that the linear optical response of GO shows a flat dispersion in the visible region. In contrast, its nonlinear optical response exhibits saturable absorption (SA) at the short wavelength and reverse saturable absorption (RSA) at the long wavelength. These results propel the application of GO in the broadband OL devices based on the RSA behavior. In addition, by controlling the fraction of sp2 and sp3 hybridizations, it also provides opportunities to tailor the NLO properties and OL performance of GO.

Two-dimensional nanomaterials and their derivatives for laser protection

To achieve simultaneous protection against both pulsed and continuous wave (CW) or quasi-CW lasers, significant research effort has been devoted to the state-of-the-art optical limiting (OL) materials and processes in an attempt to achieve some measures of protection against such laser beams in the past decades. Two-dimensional (2D) nanomaterials with a lot of unique properties, including graphene, transition metal dichalcogenides, black phosphorus and others, have aroused the extensive research interest of many researchers. In this review paper, we describe systematically the OL mechanisms and the recent achievements in the 2D nanomaterials and their organic/polymeric derivatives for laser protection. In an effort to sustain the advantage of 2D nanomaterials, one can not only introduce the functional molecules or polymers to blend with them to form a complex multi-phase material system, but also embed the soluble 2D nanosheets covalently functionalized with organic/polymeric materials in a polymer host to form host-guest composite materials that are expected to improve the OL performance of the whole system. All in all, an optimized complex multi-component nanomaterial system enormously enhances the performance and applicability of OL devices. In addition, the fundamental studies of the photophysical and photonic properties of 2D nanomaterials and their derivatives in various solid hosts are of significance for modifying the nanomaterials at a molecular level.

Al dopant-dependent third-order nonlinear optical parameters in ZnO thin films under CW Nd: YAG laser irradiation

Structural, morphological and optical properties of Al-doped ZnO thin films synthesized by the spray pyrolysis method on the FTO-coated glass substrate are investigated in this study. The measurements were carried out on a series of films with various contents of Al dopant from 0 up to 4% of Al/ZnO ratios. 2-D and 3-D atomic force microscopy images revealed that the Al content has a considerable influence on the surface morphology and roughness of thin films so that the grain size and surface roughness of the films decreased with increasing the Al contents. Room temperature PL spectra revealed UV as well as defect emission peaks which experienced a slight blue shift with Al/ZnO ratios increasing from 1 to 4%. Measurements of nonlinear optical properties of Al-doped ZnO thin films were performed using a CW Nd: YAG laser at 532 nm by the Z-scan technique. It was demonstrated that the Al-doped ZnO thin films have a negative nonlinearity can be related to the thermal effects. The optical limiting measurements confirmed that undoped and Al-doped ZnO thin films are good candidates for optical limiter devices at 532 nm wavelength of lasers. The effects of defect states on the nonlinearity of thin films are also investigated in this work.

Nonlinear optical and optical limiting properties of new structures of organic nonlinear optical materials for photonic applications

The nonlinear optical (NLO) and optical limiting (OL) properties of three new structures of organic NLO guest-host Poly(N-vinylcarbozole)/disperse orange 3 (PVK/DO3), PVK/disperse orange 13 (PVK/DO13), and PVK/disperse orange 25 (PVK/DO25) as a solution at different concentrations and as a thin-film sample are studied using continuous wave z-scan system at 532 nm. The open-aperture z-scan data of the NLO materials in the solution and thin-film samples displayed two-photon and saturable absorptions, respectively. The PVK/DO13 exhibites the largest and best values of the nonlinearities, such as n2, β, χ(3), compared with those of PVK/DO3 and PVK/DO25. This nonlinearity increases as the concentration increases. The results indicate that these NLO materials are good candidates for optical switching and OL devices.

Mechanism Studies on the Superior Optical Limiting Observed in Graphene Oxide Covalently Functionalized with Upconversion NaYF4:Yb3+/Er3+ Nanoparticles

Superior optical limiting (OL) characteristics and mechanisms are explored in a novel nanocomposite made from graphene oxide (GO) and NaYF4:Yb3+/Er3+ nanoparticles via covalent chemical bonding. Due to the synergistic effect of enhanced nonlinear scattering, two-photon absorption, and efficient energy transfer between NaYF4:Yb3+/Er3+ nanoparticles and GO, the nanocomposite displays dramatically improved OL effects compared to either GO or NaYF4:Yb3+/Er3+ nanoparticles, making it a very promising material for practical OL devices.