epoxy resin composite and study its structural, morphological and nonlinear optical properties

Optical Materials 89 (2019) 460–467

Contents lists available at ScienceDirect

Optical Materials journal homepage: www.elsevier.com/locate/optmat

Formation of graphene nanosheets/epoxy resin composite and study its structural, morphological and nonlinear optical properties

T

Ahmed S. Al-Asadia,∗, Qusay M.A. Hassana, Amjed F. Abdulkadera, Mohammed H. Mohammedb, H. Bakra, C.A. Emsharya a b

Department of Physics, College of Education for Pure Science, University of Basrah, Basrah, 61004, Iraq Department of Physics, College of Science, University of Thi-Qar, Nassiriya, 64000, Iraq

A R T I C LE I N FO

A B S T R A C T

Keywords: Graphene nanosheets Epoxy resin Liquid phase exfoliation Thermal nonlinearity Nonlinear & optical limiting properties

The attention towered the fabrication of graphene nanosheets/polymer composites have gradually boosted in the scientific research since these systems have exhibited improved thermal and mechanical stabilities and nonlinear optical properties compared to the pristine polymer. Herein, graphene nanosheets (GNS) were firstly synthesized through liquid phase exfoliation (LPE) of graphite in isopropanol then mixed with epoxy resin (ER) creating a composite of GNS/ER. The properties of the as-obtained structure were evaluated by transmission electron and ultraviolet–visible spectroscopies. The nonlinear optical properties (NLO) of GNS/ER were investigated through single beam Z-scan technique using a continuous-wave (CW) laser beam obtained from a solid-state laser (SDL). The results reveal that GNS/ER composite shows a negative nonlinear refractive index of (−0.26 × 10−8 cm2/ W). Optical limiting (OL) measurements were performed on the GNS/ER and the mechanism of the OL is ascribed to the nonlinear refraction (thermal effects). These outcomes specify the potential use of cost-effective produced GNS/ER composite to boost the NLO and OL for future photonic applications.

1. Introduction Low dimensional (LD) materials have continued to shift extensively the scientific interest due to their capability for exhibiting fabulous physical properties which enable them to be the base of several applications [1–7]. Among numerous LD materials, graphene-family nanomaterials have been broadly investigated and usually shown outstanding performances for several applications including batteries and supercapacitors, sensors, solar cells and catalytic supports [8] owing to their large specific surface area [9], high mobility of electrons [10], excellent mechanical stiffness [11], flexibility [12] as well as exceptional properties such as electrical [13] and thermal conductivities [14]. Recently, many researchers have focused their special treatments on finding suitable materials that possess high nonlinear optical properties [15–19] along with a fast response time for several photonic applications using high density optical data storage [20–23], optical limiting [24–32], optical bi-stability [33–35], all optical switches [36,37] as well as optical phase conjugation [38]. Recently, prodigious deal of attention has prearranged to study nonlinear optical properties of graphene-family nanomaterials such as graphene oxide nanosheets [39],

∗

graphene nanoribbons [40], graphene oxide colloids [41], graphene fluoride in aqueous dispersions [42] and graphene oxide [43]. Additionally, several composites based on graphene-family nanomaterials have been extensively explored to improve the NLO of the pristine graphene-family materials including conjugated polymer–graphene oxide composite [44], graphene oxide/Fe3O4 hybrid [45], graphene oxide/organic solvents [46,47], graphene oxide/silver nanocomposite [48], reduced graphene oxide/zinc oxide [49], TiO2/reduced graphene oxide nanocomposites [50], graphene oxide/bimetallic nanoparticles [51], graphene oxide/zinc (II) phthalocyanine [52,53] and graphene and carbon nanotube polymer composites [54]. Among these composites, the state-of-art has revealed that graphene nanosheets-epoxy resin composite is appropriate for many photonic related applications [55,56]. Many methods have been successfully used to form the sheets of graphene such as mechanical exfoliation, liquid phase exfoliation and chemical vapor deposition. Among these methods, liquid phase exfoliation (LPE) is introduced as one of the most promising cost-effective technique to produce single and/or multi-sheets of graphene in solution based. In this article, the fabrication of graphene nanosheets using LPE technique by exhalation the graphite powder in isopropanol is

Corresponding author. E-mail address: [email protected] (A.S. Al-Asadi).

https://doi.org/10.1016/j.optmat.2019.01.078 Received 23 September 2018; Received in revised form 26 January 2019; Accepted 27 January 2019 0925-3467/ © 2019 Elsevier B.V. All rights reserved.

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

2.2. Synthesis of graphene nanosheets/epoxy rinse

presented. Epoxy resin was added to the mixture to create a nanocomposite sample of graphene nanosheets/epoxy resin for the current study. The NLO and OL behavior of the as-prepared sample by means of CW low power visible laser beam at 473 nm wavelength are presented. The measurements of nonlinear refractive index of the graphene in epoxy resin is based on the single beam Z-scan technique. The mechanism for the optical limiting is reported, too. During most of the aforementioned nonlinear optical measurements (graphene-family nanomaterials and their composites), femto-, pico- or nano-second laser pulses were utilized to discover their nonlinear optical properties. To the extent of our knowledge, diminutive works have been concerned about using CW laser with the study of nonlinear optical properties [57,58]. Therefore, the current communication displays the nonlinear optical properties of the graphene nanosheets -epoxy resin composite in the CW regime.

Epoxy resin (ER, 368WG, density 1.27 g/cm3, molecular weight 624 g/mol) was obtained from United Chemical Company Ltd. (Unichem- Jordan). 1.5 mL of ER was added to 10 mL of the as-prepared graphene nanosheets/isopropanol solution. The obtained mixture was vigorously shaken for 1 h in a sonicator bath and left for several hours which yields homogenous graphene/epoxy resin composites (Fig. 1(c and d)) with yellow-brown dispersion as seen in Fig. 1e. The chemical formula of the epoxy resin and a photograph of the solution used in the experiment are presented in Fig. 2 a and b, respectively. The graphene nanosheets and graphene nanosheets/epoxy resin composite are denoted by GNS and GNS/ER, respectively.

2.3. Characterization methods 2. Experimental details

A transition electron microscopy (TEM) imaging system (Zeiss Supra 55vp type) was used to investigate the surface morphology of the asprepared GNS and GNS/ER. The nanostructure sheets diameter was determined from the TEM images using ImageJ software. Ultraviolet–visible spectrophotometer (UV–Vis) system (JenwayEngland) was employed to verify the optical properties of GNS and GNS/ER composite in the wavelength range 300–1000 nm using a quartz cell of 1 mm thickness. A XY2050 digital ultra-sonic system with a maximum power of 50 W was used for the liquid phase exhalation process.

2.1. Synthesis of graphene nanosheets via LPE Layers of Graphene nanosheets were obtained using LPE technique [59,60]. Commercially available graphite powder was dissolved in isopropanol (30 mg/15 mL) then placed in ultra-sonicater for 90 min (Fig. 1 a-c). The obtained mixture was left overnight to eliminate all the remaining unexfoliated graphite and to form a uniform suspension of graphene nanosheets in isopropanol solution as shown in Fig. 1f.

Fig. 1. Schematic illustration of the experimental procedure used in the present work; (from a to c) Liquid-phase exfoliation of graphite powder in the present of isopropanol alcohol to fabricate graphene nanosheets; (from c to d) Creating a composite of these nanosheets with epoxy resin; (e) and (f) showing the solution obtained for graphene nanosheets and Graphene nanosheets/epoxy resin composite, respectively. 461

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

Fig. 2. (a) Chemical structure of epoxy resin used to create a composite with graphene nanosheets and (b) photograph of the epoxy resin solution.

Fig. 3. Experimental setup for Z-scan and OL measurements.

graphite in isopropanol solvent. It is clearly obvious that the graphite powder was completely exfoliated into monolayer-to-several layer(s) of GNS due to the existence of isopropanol which breaks the interlayer van der Waals bond [61]. Flakes of GNS with large, flat, and almost circularshaped can be seen under different image magnifications (Fig. 4 a and b). The mean diameter of these flakes is estimated from the electron microscopic images to be ∼ 1μm The morphologies of GNS after dispersion in epoxy resin are shown to be slightly different. As displayed in Fig. 1(a–f), the GNS are not shown to be circular-shaped as observed previously in the pristine GNS and they form a folded assembly after adding ER to their structure. This could be due to the good dispersion and large volume to surface area ratio [55]. This folded structure is acting as mass transport barrier as well as a thermal isolator which enhances the thermal stability of the obtained structure [55].

2.4. Z-scan measurements A well-established Z-scan method which is diagrammatically displayed in Fig. 3 was used to determine the nonlinear refractive index and absorption coefficient of the as-obtained GNS/ER composite. A single-beam obtained from solid-state laser (SDL-473-050T type) with wavelength of 473 nm was utilized during the measurements. The laser beam was focused by a positive glass lens of 50 mm focal length. The waist ω0 of the laser beam at the focus as well as the Rayleigh length, ZR, are computed to be 0.019235 mm and 2.46 mm, respectively. In order to start the Z-scan measurements, the as-prepared sample was fixed on a translation stage. This stage is capable to move the sample along the z-axis, passing through the focal point of focusing lens. The transmittance of the laser-beam through a finite aperture (closed aperture) in the far-field was recorded by a photo-detector fed to a power meter as a function of the position of the GNS/ER composite along Z-axis. All the experiments were carried out at room temperature. The intensity at the focus was 3.441 kW/cm2. For the open aperture Zscan, the finite aperture was replaced by a lens to gather the whole laser beam transmitted through the GNS/ER composite.

3.2. UVe visible spectroscopic study Fig. 5 shows the UV–visible absorption spectra of GNS and GNS/ER composite. The measurements were carried out at room temperature. The absorption coefficient, α, is obtained for the examined samples using Fig. 5 and the following relation [62]:

2.5. Optical limiting technique

α = 2.303 The same experimental set up (Fig. 3) previously used in the Z-scan experiment could also be used to study the OL properties of the GNS/ER composite. During this measurement, the sample was located behind the lens focal point to obtain optimum OL characteristics. The optical limiting properties can be recorded by manipulating the input power and recording the output power.

A L

(1)

Where A and L are the absorbance and thickness of the sample, respectively. The values of α at 473 nm wavelength for the GNS and GNS/ ER composite are 0.313 cm−1 and 16.58 cm−1, respectively. 3.3. Z-scan measurements

3. Results and discussions

The open aperture z-scan has led to a straight horizontal curve for the relation between normalized transmitted power against distance, z. Arandian et al. [57] have obtained similar behavior in graphene suspensions using two CW laser beams at 532 nm and 635 nm. They also found that graphene suspensions show no nonlinear absorption at these

3.1. Surface morphology Fig. 4(a and b) shows the TEM images of GNS prepared using LPE of 462

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

Fig. 4. Surface morphology of the as-prepared GNS and GNS/ER composite: (a) and (b) showing the TEM images of GNS at different selected areas; (c) Average size of the GNS as obtained from TEM analysis; (d–f) Displaying the TEM images of GNS/ER composite.

transmittance to the distance relation. The results of Z-scan reveal that GNS/ER composite has nonlinear refraction. The Z-scan plot reveals the signature of self-defocusing (i.e. negative nonlinearity). The origin of the observed nonlinearity which is proved by the present authors by the use of CW laser beams that the observed nonlinearities are thermal in nature [62–68]. To compute the value of n2 for GNS/ER composite, the thermal lens model (TLM), which was developed by Cuppo et al. [69], could be applied instead of the Z-scan technique established by SheikBahae et al., [70]. To check the possibility of using TLM of Z-scan, one can calculate the separation [69] ΔZ p-v between the transmittances at peak/valley in the z direction, which should be approximately equal to 2ZR. In this study, the value of ZR is 2.92 mm, so that ΔZ p-v = 4.96 mm. According to Fig. 6, the separation ΔZ p-v between the transmittances at peak and valley in the z direction is 5 mm, which is closely equal to 2ZR and thus it is possible to apply the TLM of Z-scan. In the TLM, the nonlinear phase shift, |θ|, is specified by Ref. [69]: Fig. 5. The absorbance spectra of GNS and GNS/ER composite. Inset is an amplified part of absorbance versus wavelength λ .

θ =

ΔTp − v 2

(2)

Where ΔT p-v is the differences between the transmittances at peak and valley and thus the value of n2 is estimated for the prepared sample using Eq. (3) [71]:

two wavelengths. To determine the nonlinear refractive index (n↓ 2 of GNS/ER composite, close aperture Z-scan was performed on the GNS/ER sample using 3.441 kW/cm2 as incident intensity. Fig. 6 displays the closedaperture Z-scan indicating a peak followed by a valley in the

n2 =

463

ΔTp − v λ 4πLIo

(3)

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

Fig. 6. Closed aperture Z-scan data for the GNS/ER composite.

Where λ is the wavelength of the laser beam. The value of n2 for GNS/ER composite is calculated by using Eq. (3) and Fig. 6 and it is found to be (−0.26 × 10−8 cm2/W).

the possibility of using the prepared sample as optical limiters. An optical limiting behavior of the GNS/ER composite is shown in Fig. 7. It can be seen that the sample displays an optical limiting effect whereas the output power was increasing linearly with the increase of low input power at the beginning. This process was changed when the input power was higher leading to a decline of the output power until it becomes constant. According to Fig. 7, it can be seen that the transmittance decreased rapidly with increasing the input power, but the transmittance differed slightly as per increasing the input power. To further determine the efficiency of the material as an optical limiter, an important parameter which is known as the optical limiting threshold is

3.4. Optical limiting Optical limiting is considered as one of the most significant application in nonlinear optics, which is used to protect optical instruments such as solid-state sensors and human eye against optical damage due the high intensity of the laser beams. The nonlinear transmittance of GNS/ER composite was studied as a function of input power to examine

Fig. 7. Optical limiting performance of GNS/ER composite. 464

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

Fig. 8. Normalized transmission curve of OL for GNS/ER composite.

4. Conclusion

required to be determined. This term can be defined as value of the input power that corresponded to 50% drop of the linear transmittance of the sample. As a result of this definition, the threshold value for GNS/ ER composite is estimated from Fig. 8 and found to be 24 mW. There are several mechanisms have been suggested to explain the optical limiting behavior for any sample such as nonlinear refraction (electronics or thermal effects [72]), nonlinear absorption (reverse saturable absorption and multiphoton absorption [73]), and nonlinear scattering [74–76]. To examine the contribution of nonlinear scattering in the OL during the measurements, the scattered radiation was monitored of the GNS/ER composite at various angles in respect of the beam axis. No scattered radiation was observed which proves that scattering does contribute to the optical limiting. The absence of nonlinear absorption indicates [64] no possibility of neither reverse saturable absorption occurring nor two-photon absorption to occur when CW laser is used. These outcomes are identical to the results acquired through the open aperture Z-scan measurements, where the sample did not display nonlinear absorption. For GNS/ER composite, the mechanism is nonlinear refraction (thermal effects). Since CW laser beam is used in this study, it is expected that the major contribution of the observed optical limiter behavior is thermal in nature. The absorbed energy by the GNS/ER composite through linear absorption causes heating up the medium which leads to a temperature gradient. Due to the reduction of refractive index of the GNS/ER with intensity of Gaussian distribution, the sample behave like a divergent lens. The existing of this thermal lens leads to a distortion of the phase of the propagating beam. The thermal lens causes self-defocusing for incident laser beam. As a result of this effect, a greater part of the crosssection of beam is cut off by the aperture whereas the transmittance recorded by the photo-detector remains almost constant. Therefore, the sample behave as an optical limiter. As a result of the use of low input laser beam power, no change to the properties of GNS/ER composite appears to occur. This was examined by repeating the spectroscopic study through same range. To illustrate, as the liquid heated up locally because of the absorption of a part of the laser beam, this portion of the medium suffers upward convection and replaced by a new part. This reduces the possibility of optical damage to the liquid indicating a high laser damage threshold.

Graphene nanosheets were successfully obtained using well-established LPE method. The composite of Graphene nanosheets with epoxy resin was then synthesized in order to explore the NLO using a single beam Z-scan technique. The closed aperture Z-scan technique was utilized to evaluate the nonlinear refractive index of the GNS/ER composite using a CW laser beam at 473 nm wavelength. The results showed that the sample did not display nonlinear absorption at this wavelength and showing self-defocusing effect with a large negative nonlinear refractive index. The nonlinear refractive index of the GNS/ ER composite is ascribed to the thermal nonlinearity which originated due to the absorption of radiation of incident laser beam by the GNS/ER composite. Also, the optical limiting characteristics of GNS/ER composite are reported. No change to the GNS/ER composite properties were noticed post irradiation with the lower power of 40 mW (intensity of 6885 W/cm2) through the measurements of the absorbance spectra in the same range of 300–1000 nm. The current investigations suggest the possible use of combination of graphene nanosheets and polymer nanocomposite for high performance upcoming photonic applications in the CW low power regime. Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References [1] A.S. Al-Asadi, L.A. Henley, S. Ghosh, A. Quetz, I. Dubenko, N. Pradhan, L. Balicas, N. Perea-Lopez, V. Carozo, Z. Lin, Fabrication and characterization of ultraviolet photosensors from ZnO nanowires prepared using chemical bath deposition method, J. Appl. Phys. 119 (2016) 084306. [2] A.S. Al-Asadi, L.A. Henley, M. Wasala, B. Muchharla, N. Perea-Lopez, V. Carozo, Z. Lin, M. Terrones, K. Mondal, K. Kordas, Aligned carbon nanotube/zinc oxide nanowire hybrids as high performance electrodes for supercapacitor applications, J. Appl. Phys. 121 (2017) 124303. [3] A.S. Al-Asadi, J. Zhang, J. Li, R.A. Potyrailo, A. Kolmakov, Design and application of variable temperature setup for scanning electron microscopy in gases and liquids at ambient conditions, Microsc. Microanal. 21 (2015) 765–770.

465

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

85 (2018) 500–509. [33] H. Chen, D. Gao, L. Gao, Effective nonlinear optical properties and optical bistability in composite media containing spherical particles with different sizes, Optic Express 24 (2016) 5334–5345. [34] E. Koushki, H.A. Doost, M.M. Ara, Optical bistability in gold nano-colloid due to thermal lensing effect, J. Phys. Chem. Solid. 87 (2015) 158–162. [35] M.M. Ara, E. Koushki, H.A. Doost, Optical bistability in TiO2 nanoparticles, Opt. Mater. 35 (2013) 1431–1435. [36] F.Z. Henari, Optical switching in organometallic phthalocyanine, J. Optic. Pure Appl. Optic. 3 (2001) 188–190. [37] M.F. Al-Mudhaffer, A.Y. Al-Ahmad, QusayM.A. Hassan, C.A. Emshary, Optical characterization and all-optical switching of benzenesulfonamide azo dye, Optik 127 (2016) 1160–1166. [38] QusayM.A. Hassan, P. Palanisamy, Optical phase conjugation by degenerate fourwave mixing in basic green 1 dye-doped gelatin film using He–Ne laser, Optic Laser. Technol. 39 (2007) 1262–1268. [39] H. Zhang, S. Virally, Q. Bao, L.K. Ping, S. Massar, N. Godbout, P. Kockaert, Z-scan measurement of the nonlinear refractive index of graphene, Optic Lett. 37 (2012) 1856–1858. [40] M. Feng, H. Zhan, Y. Chen, Nonlinear optical and optical limiting properties of graphene families, Appl. Phys. Lett. 96 (2010) 033107. [41] M. Kavitha, H. John, P. Gopinath, R. Philip, Synthesis of reduced graphene oxide–ZnO hybrid with enhanced optical limiting properties, J. Mater. Chem. C 1 (2013) 3669–3676. [42] A.B. Bourlinos, A. Bakandritsos, N. Liaros, S. Couris, K. Safarova, M. Otyepka, R. Zbořil, Water dispersible functionalized graphene fluoride with significant nonlinear optical response, Chem. Phys. Lett. 543 (2012) 101–105. [43] X.-F. Jiang, L. Polavarapu, S.T. Neo, T. Venkatesan, Q.-H. Xu, Graphene oxides as tunable broadband nonlinear optical materials for femtosecond laser pulses, J. Phys. Chem. Lett. 3 (2012) 785–790. [44] V. Nalla, L. Polavarapu, K.K. Manga, B.M. Goh, K.P. Loh, Q.-H. Xu, W. Ji, Transient photoconductivity and femtosecond nonlinear optical properties of a conjugated polymer–graphene oxide composite, Nanotechnology 21 (2010) 415203. [45] X.-L. Zhang, X. Zhao, Z.-B. Liu, S. Shi, W.-Y. Zhou, J.-G. Tian, Y.-F. Xu, Y.-S. Chen, Nonlinear optical and optical limiting properties of graphene oxide–Fe3O4 hybrid material, J. Optic. 13 (2011) 075202. [46] N. Liaros, E. Koudoumas, S. Couris, Broadband near infrared optical power limiting of few layered graphene oxides, Appl. Phys. Lett. 104 (2014) 191112. [47] N. Liaros, K. Iliopoulos, M. Stylianakis, E. Koudoumas, S. Couris, Optical limiting action of few layered graphene oxide dispersed in different solvents, Opt. Mater. 36 (2013) 112–117. [48] S. Biswas, A. Kole, C. Tiwary, P. Kumbhakar, Enhanced nonlinear optical properties of graphene oxide–silver nanocomposites measured by Z-scan technique, RSC Adv. 6 (2016) 10319–10325. [49] N. Liaros, P. Aloukos, A. Kolokithas-Ntoukas, A. Bakandritsos, T. Szabo, R. Zboril, S. Couris, Nonlinear optical properties and broadband optical power limiting action of graphene oxide colloids, J. Phys. Chem. C 117 (2013) 6842–6850. [50] A. Wang, W. Yu, Y. Fang, Y. Song, D. Jia, L. Long, M.P. Cifuentes, M.G. Humphrey, C. Zhang, Facile hydrothermal synthesis and optical limiting properties of TiO2reduced graphene oxide nanocomposites, Carbon 89 (2015) 130–141. [51] C. Zheng, W. Li, X. Xiao, X. Ye, W. Chen, Synthesis and optical limiting properties of graphene oxide/bimetallic nanoparticles, Optik 127 (2016) 1792–1796. [52] Z. Wang, C. He, W. Song, Y. Gao, Z. Chen, Y. Dong, C. Zhao, Z. Li, Y. Wu, The effect of peripheral substituents attached to phthalocyanines on the third order nonlinear optical properties of graphene oxide–zinc (II) phthalocyanine hybrids, RSC Adv. 5 (2015) 94144–94154. [53] J. Zhu, Y. Li, Y. Chen, J. Wang, B. Zhang, J. Zhang, W.J. Blau, Graphene oxide covalently functionalized with zinc phthalocyanine for broadband optical limiting, Carbon 49 (2011) 1900–1905. [54] J. Wang, Y. Chen, R. Li, H. Dong, Y. Ju, J. He, J. Fan, K. Wang, K.-S. Liao, L. Zhang, Graphene and carbon nanotube polymer composites for laser protection, J. Inorg. Organomet. Polym. Mater. 21 (2011) 736–746. [55] S. Liu, H. Yan, Z. Fang, H. Wang, Effect of graphene nanosheets on morphology, thermal stability and flame retardancy of epoxy resin, Compos. Sci. Technol. 90 (2014) 40–47. [56] A. Li, C. Zhang, Y.F. Zhang, Graphene nanosheets‐filled epoxy composites prepared by a fast dispersion method, J. Appl. Polym. Sci. 134 (2017) 45152. [57] A. Arandian, R. Karimzadeh, S. Faizabadi, The effect of laser wavelength and concentration on thermal nonlinear refractive index of graphene suspensions, Nano 10 (2015) 1550053. [58] M. Saravanan, S.G. TC, G. Vinitha, Facile hydrothermal synthesis of CdFe2O4-reduced graphene oxide nanocomposites and their third-order nonlinear optical properties under CW excitation, J. Mol. Liq. 256 (2018) 519–526. [59] A. Ciesielski, P. Samorì, Graphene via sonication assisted liquid-phase exfoliation, Chem. Soc. Rev. 43 (2014) 381–398. [60] V. Nicolosi, M. Chhowalla, M.G. Kanatzidis, M.S. Strano, J.N. Coleman, Liquid exfoliation of layered materials, Science 340 (2013) 1226419. [61] A. O'Neill, U. Khan, P.N. Nirmalraj, J. Boland, J.N. Coleman, Graphene dispersion and exfoliation in low boiling point solvents, J. Phys. Chem. C 115 (2011) 5422–5428. [62] A.J. Kadhum, N.A. Hussein, QusayM.A. Hassan, H. Sultan, A.S. Al-Asadi, C. Emshary, Investigating the nonlinear behavior of cobalt (II) phthalocyanine using visible CW laser beam, Optik 157 (2018) 540–550. [63] QusayM.A. Hassan, A.Y. Al-Ahmad, M.F. Al-Mudhaffer, H.A. Badran, Third-order optical nonlinearities and optical-limiting properties of phloxine b dye doped pmma films investigated by z-scan technique, Rom. J. Phys. 58 (2013) 962–969.

[4] D.-X. Li, W. Xiong, The electronic structure and effective excitonic g factors of GaAs/GaMnAs core-shell nanowires, Superlattice. Microst. 112 (2017) 584–595. [5] T. Gholami, M. Salavati-Niasari, M. Bazarganipour, E. Noori, Synthesis and characterization of spherical silica nanoparticles by modified Stöber process assisted by organic ligand, Superlattice. Microst. 61 (2013) 33–41. [6] A. Manikandan, J.J. Vijaya, M. Sundararajan, C. Meganathan, L.J. Kennedy, M. Bououdina, Optical and magnetic properties of Mg-doped ZnFe2O4 nanoparticles prepared by rapid microwave combustion method, Superlattice. Microst. 64 (2013) 118–131. [7] M.H. Mohammed, A.S. Al-Asadi, F.H. Hanoon, Semi-metallic bilayer MS2 (M= W, Mo) induced by Boron, carbon, and Nitrogen impurities, Solid State Commun. 282 (2018) 28–32. [8] T. Remyamol, H. John, P. Gopinath, Synthesis and nonlinear optical properties of reduced graphene oxide covalently functionalized with polyaniline, Carbon 59 (2013) 308–314. [9] S. Stankovich, D.A. Dikin, G.H. Dommett, K.M. Kohlhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Nguyen, R.S. Ruoff, Graphene-based composite materials, Nature 442 (2006) 282. [10] S. Husaini, J. Slagle, J. Murray, S. Guha, L. Gonzalez, R. Bedford, Broadband saturable absorption and optical limiting in graphene-polymer composites, Appl. Phys. Lett. 102 (2013) 191112. [11] C. Lee, X. Wei, J.W. Kysar, J. Hone, Measurement of the elastic properties and intrinsic strength of monolayer graphene, Science 321 (2008) 385–388. [12] D.A. Dikin, S. Stankovich, E.J. Zimney, R.D. Piner, G.H. Dommett, G. Evmenenko, S.T. Nguyen, R.S. Ruoff, Preparation and characterization of graphene oxide paper, Nature 448 (2007) 457. [13] H.B. Heersche, P. Jarillo-Herrero, J.B. Oostinga, L.M. Vandersypen, A.F. Morpurgo, Bipolar supercurrent in graphene, Nature 446 (2007) 56. [14] A.A. Balandin, S. Ghosh, W. Bao, I. Calizo, D. Teweldebrhan, F. Miao, C.N. Lau, Superior thermal conductivity of single-layer graphene, Nano Lett. 8 (2008) 902–907. [15] B. Sahraoui, X.N. Phu, M. Sallé, A. Gorgues, Electronic and nuclear contributions to the third-order nonlinear optical susceptibilities of new pN, N'-dimethylaniline tetrathiafulvalene derivatives, Optic Lett. 23 (1998) 1811–1813. [16] B. Sahraoui, G. Rivoire, Degenerate four-wave mixing in absorbing isotropic media, Optic Commun. 138 (1997) 109–112. [17] I. Rau, F. Kajzar, J. Luc, B. Sahraoui, G. Boudebs, Comparison of Z-scan and THG derived nonlinear index of refraction in selected organic solvents, J. Opt. Soc. Am. B 25 (2008) 1738–1747. [18] K. Iliopoulos, I. Guezguez, A. Kerasidou, A. El-Ghayoury, D. Branzea, G. Nita, N. Avarvari, H. Belmabrouk, S. Couris, B. Sahraoui, Effect of metal cation complexation on the nonlinear optical response of an electroactive bisiminopyridine ligand, Dyes Pigments 101 (2014) 229–233. [19] B. Kulyk, A.P. Kerasidou, L. Soumahoro, C. Moussallem, F. Gohier, P. Frère, B. Sahraoui, Optimization and diagnostic of nonlinear optical features of π-conjugated benzodifuran-based derivatives, RSC Adv. 6 (2016) 14439–14447. [20] S. Manickasundaram, P. Kannan, R. Kumaran, R. Velu, P. Ramamurthy, QusayM.A. Hassan, P. Palanisamy, S. Senthil, S.S. Narayanan, Holographic grating studies in pendant xanthene dyes containing poly (alkyloxymethacrylate) s, J. Mater. Sci. Mater. Electron. 22 (2011) 25–34. [21] QusayM.A. Hassan, P. Palanisamy, S. Manickasundaram, P. Kannan, Sudan IV dye based poly (alkyloxymethacrylate) films for optical data storage, Optic Commun. 267 (2006) 236–243. [22] S. Manickasundaram, P. Kannan, QusayM.A. Hassan, P. Palanisamy, Azo dye based poly (alkyloxymethacrylate) s and their spacer effect on optical data storage, J. Mater. Sci. Mater. Electron. 19 (2008) 1045–1053. [23] S. Manickasundaram, P. Kannan, QusayM.A. Hassan, P. Palanisamy, Holographic grating formation in poly (methacrylate) containing pendant xanthene dyes, Optoelectronics And Advanced Materials-Rapid Communications 2 (2008) 324–331. [24] R. Manshad, QusayM.A. Hassan, Optical limiting properties of magenta doped PMMA under CW laser illumination, Adv. Appl. Sci. Res. 3 (2012) 3696–3702. [25] QusayM.A. Hassan, R.K. Manshad, Optical limiting properties of Sudan red B in solution and solid film, Opt. Quant. Electron. 47 (2015) 297–311. [26] E.A. Al-Nasir, A.Y. Al-Ahmad, A.A. Hussein, QusayM.A. Hassan, A.A. Sultan, A.H. Al-Mowali, Low optical limiting and nonlinear optical properties of vanadyl phthalocyanine using a CW laser, Chem. Mater. Res. 3 (2013) 18–25. [27] QusayM.A. Hassan, Nonlinear optical and optical limiting properties of chicago sky blue 6B doped PVA film at 633 nm and 532 nm studied using a continuous wave laser, Mod. Phys. Lett. B 22 (2008) 1589–1597. [28] H. Sultan, QusayM.A. Hassan, H. Bakr, A.S. Al-Asadi, D. Hashim, C. Emshary, Thermal-induced nonlinearities in rose, linseed, and chamomile oils using continuous wave visible laser beam, Can. J. Phys. 96 (2017) 157–164. [29] A.F. Abdulkader, QusayM.A. Hassan, A.S. Al-Asadi, H. Bakr, H. Sultan, C. Emshary, Linear, nonlinear and optical limiting properties of carbon black in epoxy resin, Optik 160 (2018) 100–108. [30] H.A. Badran, A.A. Al-Fregi, R.F. Alfahed, A.S. Al-Asadi, Study of thermal lens technique and third-order nonlinear susceptibility of PMMA base containing 5′, 5′′dibromo-o-cresolsulfophthalein, J. Mater. Sci. Mater. Electron. 28 (2017) 17288–17296. [31] QusayM.A. Hassan, Investigation on the nonlinear optical properties and optical power limiting of parsley oil, International Journal of Photonics and Optical Technology 3 (2017) 17–20. [32] M.A. Hassan Qusay, H.A. Sultan, Ahmed S. Al-Asadi, Rita S. Elias, H. Bakr, Bahjat A. Saeed, C.A. Emsharya, Far-field diffraction patterns and optical limiting properties of bisdemethoxycurcumin solution under CW laser illumination, Opt. Mater.

466

Optical Materials 89 (2019) 460–467

A.S. Al-Asadi, et al.

[64] QusayM.A. Hassan, Study of nonlinear optical properties and optical limiting of acid green 5 in solution and solid film, Optic Laser. Technol. 106 (2018) 366–371. [65] R.S. Elias, QusayM.A. Hassan, H. Sultan, A.S. Al-Asadi, B.A. Saeed, C. Emshary, Thermal nonlinearities for three curcuminoids measured by diffraction ring patterns and Z-scan under visible CW laser illumination, Optic Laser. Technol. 107 (2018) 131–141. [66] C. Emshary, D. Hashim, H. Bakr, A.S. Al-Asadi, H. Sultan, QusayM.A. Hassan, Diffraction ring patterns and z-scan measurements of nonlinear refractive index of khoba vegetable oil, Journal of Basrah Researches (Sciences) 44 (2018) 47–63. [67] QusayM.A. Hassan, Optical properties of vanadyl phthalocyanine thin films and nonlinear refractive index of vanadyl phthalocyanine doped PMMA by using thermal lens spectrometry technique, J. Nat. Sci. Res. 4 (2014) 97–108. [68] QusayM.A. Hassan, Third-order nonlinearities and optical limiting properties of rose Bengal at 532 nm wavelength, Journal of Basrah Researches (Sciences) 33 (2007) 76–82. [69] F.L.S.A. Cuppo, A.M.F. Neto, S.L. Gómez, P. Palffy-Muhoray, Thermal-lens model compared with the Sheik-Bahae formalism in interpreting Z-scan experiments on lyotropic liquid crystals, J. Opt. Soc. Am. B 19 (2002) 1342–1348. [70] M. Sheik-Bahae, A.A. Said, T.-H. Wei, D.J. Hagan, E.W. Van Stryland, Sensitive

[71]

[72] [73]

[74]

[75] [76]

467

measurement of optical nonlinearities using a single beam, IEEE J. Quantum Electron. 26 (1990) 760–769. K. Sendhil, C. Vijayan, M. Kothiyal, Low-threshold optical power limiting of cw laser illumination based on nonlinear refraction in zinc tetraphenyl porphyrin, Optic Laser. Technol. 38 (2006) 512–515. B.L. Justus, A.L. Huston, A.J. Campillo, Broadband thermal optical limiter, Appl. Phys. Lett. 63 (1993) 1483–1485. A. Said, M. Sheik-Bahae, D.J. Hagan, T. Wei, J. Wang, J. Young, E.W. Van Stryland, Determination of bound-electronic and free-carrier nonlinearities in ZnSe, GaAs, CdTe, and ZnTe, J. Opt. Soc. Am. B 9 (1992) 405–414. K.M. Nashold, D.P. Walter, Investigations of optical limiting mechanisms in carbon particle suspensions and fullerene solutions, J. Opt. Soc. Am. B 12 (1995) 1228–1237. K. Mansour, M. Soileau, E.W. Van Stryland, Nonlinear optical properties of carbonblack suspensions (ink), J. Opt. Soc. Am. B 9 (1992) 1100–1109. V. Joudrier, P. Bourdon, F. Hache, C. Flytzanis, Characterization of nonlinear scattering in colloidal suspensions of silica particles, Appl. Phys. B 70 (2000) 105–109.