Nonlinear Optical Properties Of Graphene Research Articles

The Optical and Structural Properties of Cu Nanoparticles: Graphene Prepared by Pulsed Laser Ablation in Deionized Water

Background: In this paper, graphene and copper oxide nanoparticles and graphene-based copper oxide nanoparticles have been produced by means of a pulsed laser ablation process (PLA) in a deionized water solution. Methods: The composition ratio of materials has been investigated in the structure of the prepared materials and their optical properties. The absorbance of the samples was obtained by the UV-VIS single beam spectrophotometer in the wavelength range of 290 to 800 nm. Spectroscopic ellipsometry method was used to investigate the linear optical properties of the samples including the real and imaginary parts of refractive index and dielectric function of the samples. The preferred model in the dielectric function modeling was Tauc-Lorentz. Also, the energy band gap of the samples has been calculated using Tauc relation. In addition, the nonlinear optical properties of graphene based copper oxide have been studied by Z-scan technique. Structure of the samples was studied using TEM image. Results: The most and the least absorbance at 532 nm wavelength, and also band gap energy belong to 1.4 ml Gr-0.6 ml Cu and copper oxide, respectively. Conclusion: The band gap energies of the samples were calculated between 3.30 eV and 3.43 eV. The real and imaginary parts of the complex refractive index were obtained in the order of 10-8cm2/W and 10-5cm/W. The results for nonlinear properties show that these samples are suitable for all-optical switching devices.

Design of All-Optical Subtractors Utilized with Plasmonic Ring Resonators for Optical Computing

In this paper, a novel plasmonic all-optical half-subtractor and full-subtractor are designed for optical computing. The structure of plasmonic subtractors consists of a metal–insulator–metal (MIM) waveguide and rectangular ring resonators covered by a graphene layer. Due to the nonlinear optical properties of graphene, the states of the plasmonic resonators can be controlled by the pump intensity of a pump beam focused on the graphene layer. The resonators can work as all-optical switches with an ultra-fast response time to constitute optical logic devices according to the directed logic mechanism. A finite-difference time-domain method is utilized to numerically investigate the transmission of the output signals which represent the results of subtraction operations. Simulation results obtained indicate that the proposed plasmonic devices have the ability to implement half-subtraction and full-subtraction with a small feature size and fast response time, and provide a new concept and method for the design and realization of optical computing devices.

Integrated plasmonic full adder based on cascaded rectangular ring resonators for optical computing

A novel and integrated plasmonic full adder based on cascaded rectangular ring resonators for optical computing is presented. This full adder consists of cascaded rectangular ring resonators covered by graphene layer and resonator-enhanced waveguide crossings. Owing to the nonlinear optical properties of graphene, the plasmonic resonators can work as all-optical switches with low power consumption and ultrashort response time to change the propagation path of surface plasmon polaritons (SPPs). Finite-difference time-domain (FDTD) simulation results numerically verify the realization of full-adder operations. This proposed plasmonic device can realize the optical full-adder operations with small feature size, fast response time, and lower power consumption than when using other traditional nonlinear optical Kerr materials. It can provide new concepts to design novel optical computing devices.

Electronic and nonlinear optical properties of doped/undoped graphene via coronene based models: a DFT study

Coronene C24H12 can be considered as graphene nanoflakes. This aromatic hydrocarbon allows for detailed calculations and the rapid evaluation of a variety of doped structures while maintaining the periodic aromaticity of graphene. In this study, through density functional theory (DFT) at the B3LYP (BECKE 3-PARAMETER LEE-YANG-PARR) functional with a 6-31G (d) basis set, we have investigated the effects of substituting carbon atoms with B, N, and O on the electronic structure, linear and nonlinear optical properties of graphene. Therefore, we found that the bandgap varies as a function of the considered structure.

Modeling and simulation of all-optical diffractive neural network based on nonlinear optical materials.

In this Letter, we propose an all-optical diffractive deep neural network modeling method based on nonlinear optical materials. First, the nonlinear optical properties of graphene and zinc selenide (ZnSe) are analyzed. Then the optical limiting effect function corresponding to the saturation absorption coefficient of the nonlinear optical materials is fitted. The optical limiting effect function is taken as the nonlinear activation function of the neural network. Finally, the all-optical diffractive neural network model based on nonlinear materials is established. The numerical simulation results show that the model can effectively improve the nonlinear representation ability of the all-optical diffractive neural network. It provides a theoretical support for the further realization of a photonic artificial intelligence chip based on nonlinear optical materials.

Linear and Nonlinear Optical Properties of Graphene: A Review

This article gives a brief overview of the linear and nonlinear optical response of graphene and its applications. Graphene exhibits unique physical properties. The charge carriers in graphene follow the relativistic massless Dirac equation; thus, they are known as the Dirac fermions. These Dirac fermions in graphene exhibit peculiar linear band structure at the Dirac point in the first Brillouin zone. These carriers exhibit novel linear and nonlinear optical properties in the presence of an intense electromagnetic field. The unique optical properties (linear and nonlinear) are a consequence of the unusual low-energy electronic band structure of graphene. The linear and nonlinear optical response of graphene can be tuned in the terahertz regime by the application of magnetic field. The uniqueness of graphene is shown by different findings in nonlinear optics such as four-wave mixing, saturation and reverse saturation absorption, two-photon absorption and optical limiting, among others. Therefore, the present review article describes the recent development in the field of linear and nonlinear optics of graphene. The different applications of graphene in the context of optics have been highlighted.

Exploiting interband transitions in graphene for optical harmonic generation

Researchers show that the nonlinear optical properties of graphene produce a different tuning mechanism.

Nonlinear Optical Properties of Materials Based on Graphene Oxide: A Review

Background: Nonlinear optical properties of Graphene and Graphene Oxide have been widely used in industry and academia. Graphene oxide disperses easily in water and has easier interaction with other materials because of the presence of oxygen groups. So, this feature of Graphene oxide enables us to manipulate its nonlinear optical properties by combining it with other nanoparticles. Objective: We introduced recent advances in the nonlinear optical properties of materials based on Graphene oxide. Methods: Nonlinear optical properties and optical limiting of Graphene oxide and/or its composites with various nanoparticles, considering the wavelength and the incident pulse width, are investigated in this review. Conclusion: At low intensities and in all pulse regimes, saturation absorption seems to be the dominant mechanism of nonlinear absorption in Graphene oxide, while at higher intensities, the main mechanism is the reverse saturation absorption. In the regime of very short pulses of picoseconds and femtoseconds, the dominant mechanisms of two-photon and multiphoton absorption lead to reverse saturation. In the nanosecond pulse regime, long laser pulses and short pulses with high pulse repetition rates, excited-state absorption and nonlinear scattering due to thermal effects are causing the nonlinear process.

Nonlinear optical properties of graphene and pyrolytic carbon: A comparative study

We report on [Formula: see text]-scan investigations of the nonlinear optical properties of thin pyrolytic carbon films and two- and three-layer graphene films, utilizing an 800[Formula: see text]nm pulsed laser generating ultrashort 180[Formula: see text]fs pulses. We analyze the sign and magnitude of nonlinear refraction and absorption in these materials, given contradictory results in this respect in the literature. In particular, we find that nonlinear refraction of graphene changes sign with changing light intensity with concomitant subtle changes in nonlinear absorption, a behavior not reported previously that suggests an interplay of several mechanisms that depend on intensity. Pyrolytic carbon films, on the contrary, exhibit positive refraction, whose magnitude (nonlinear refractive index [Formula: see text][Formula: see text]cm2/W) is comparable to that of graphene, and strong negative absorption, i.e., bleaching, contrary to previously reported results. We discuss implications and possible mechanisms of the observed phenomena.

Ultrafast saturable absorption dynamics in hybrid graphene/Si3N4 waveguides

We study the nonlinear optical properties of graphene integrated onto Si3N4 waveguides under picosecond and subpicosecond pulsed excitation at telecom wavelength. Saturable absorption of graphene under guided-mode excitation is measured, and the temporal effects related to the photoexcited carrier dynamics in graphene are highlighted. Thereafter, a model of photoexcited carriers in graphene is implemented into the nonlinear Schrodinger equation in order to simulate the pulse propagation across the hybrid graphene/Si3N4 waveguide. This allows us to extract phenomenological parameters of graphene saturable absorption in chip-based devices, which could provide some guidelines for the design of nonlinear elements in photonic integrated circuits.

Gate-Tunable Nonlinear Refraction and Absorption in Graphene-Covered Silicon Nitride Waveguides

The nonlinear optical properties of graphene have received significant interest in the past years. Especially third-order nonlinear effects have been demonstrated to be large. Recently several grou...

Polarization control using passive and active crossed graphene gratings.

Graphene gratings provide a promising route towards the miniaturization of THz metasurfaces and other photonic devices, chiefly due to remarkable optical properties of graphene. In this paper, we propose novel graphene nanostructures for passive and active control of the polarization state of THz waves. The proposed devices are composed of two crossed graphene gratings separated by an insulator spacer. Because of specific linear and nonlinear properties of graphene, these optical metasurfaces can be utilized as ultrathin polarization converters operating in the THz frequency domain. In particular, our study shows that properly designed graphene polarizers can effectively select specific polarization states, their thickness being about a tenth of the operating wavelength and size more than 80× smaller than that of similar metallic devices. Equally important, we demonstrate that the nonlinear optical properties of graphene can be utilized to actively control the polarization state of generated higher harmonics.

Graphene Fibers: Manipulation of Nonlinear Optical Properties of Graphene Bonded Fiber Devices by Thermally Engineering Fermi–Dirac Distribution (Advanced Optical Materials 21/2017)

Graphene Fibers: Manipulation of Nonlinear Optical Properties of Graphene Bonded Fiber Devices by Thermally Engineering Fermi–Dirac Distribution (Advanced Optical Materials 21/2017)

Manipulation of Nonlinear Optical Properties of Graphene Bonded Fiber Devices by Thermally Engineering Fermi–Dirac Distribution

AbstractGraphene's atomic thickness, gapless Dirac–Fermionic band structure, and large thermal conductivity make it a promising element for applications in photonic integrated devices. Importantly, actively tunable graphene‐waveguide‐integrated optoelectronic devices can potentially be utilized for the realization of reconfigurable photonic systems. Since electrical device control is always preferred, researchers have previously demonstrated gate‐variable graphene devices; however, electrical control remains challenging, particularly in all‐fiber systems because of the required complicated configuration and fabrication techniques along with additional signal loss. Here, a graphene‐fiber‐integrated platform is proposed and the manipulation of its nonlinear optical properties is demonstrated by engineering the Fermi–Dirac distribution of graphene based on a convenient electric heating method. For the first time, it is experimentally shown that the nonlinear optical absorption of graphene is correlated to temperature via the thermal relaxation process. In the experiments, the modulation depth variation exceeds 60%. The configuration is simple, cost‐effective, and can be readily extended to other 2D materials. It is believed that this work can contribute to building miniature and compact graphene‐fiber‐integrated devices for actively tunable multifunctional applications.

Ultrafast Nonlinear Optical Properties of a Graphene Saturable Mirror in the 2 μm Wavelength Region

AbstractMid‐infrared ultrafast lasers have emerged as a promising platform for both science and industry because of their inherent high raw power and eye‐safe spectrum. 2D nanostructures such as graphene have emerged as promising photonic materials for laser mode‐locking to generate ultrashort pulses. However, there are still many unanswered questions about graphene's key advantages to be practical devices, especially over the matured semiconductor saturable absorber mirror (SESAM). In this work, we conducted systematic comparisons on the nonlinear optical properties of graphene and that of a commercial SESAM at 2 μm wavelength. Our results showed that graphene has significant advantages over the commercial SESAM, exhibiting ∼28% less absorptive cross‐section ratio of excited‐state to ground‐state and ∼50 times faster relaxation time. This implies that graphene can be exploited as a better mode‐locker than the current commercial SESAM for high power, high repetition rate and ultrafast mid‐infrared laser sources.

Theoretical and computational analysis of second- and third-harmonic generation in periodically patterned graphene and transition-metal dichalcogenide monolayers

Remarkable optical and electrical properties of two-dimensional (2D) materials, such as graphene and transition-metal dichalcogenide (TMDC) monolayers, offer vast technological potential for novel and improved optoelectronic nanodevices, many of which relying on nonlinear optical effects in these 2D materials. This article introduces a highly effective numerical method for efficient and accurate description of linear and nonlinear optical effects in nanostructured 2D materials embedded in periodic photonic structures containing regular three-dimensional (3D) optical materials, such as diffraction gratings and periodic metamaterials. The proposed method builds upon the rigorous coupled-wave analysis and incorporates the nonlinear optical response of 2D materials by means of modified electromagnetic boundary conditions. This allows one to reduce the mathematical framework of the numerical method to an inhomogeneous scattering matrix formalism, which makes it more accurate and efficient than previously used approaches. An overview of linear and nonlinear optical properties of graphene and TMDC monolayers is given and the various features of the corresponding optical spectra are explored numerically and discussed. To illustrate the versatility of our numerical method, we use it to investigate the linear and nonlinear multiresonant optical response of 2D-3D heteromaterials for enhanced and tunable second- and third-harmonic generation. In particular, by employing a structured 2D material optically coupled to a patterned slab waveguide, we study the interplay between geometric resonances associated to guiding modes of periodically patterned slab waveguides and plasmon or exciton resonances of 2D materials.

Influence of doping level on the structure, texture, and nonlinear optical properties of graphene oxide/Au hybrids doped ORMOSIL gel glasses

Graphene oxide (GO)/Au nanoparticle (NP) hybrids were introduced into nanostructured sol–gel organically modified silica (ORMOSIL) using a sol–gel technique. Scanning electron microscopy, Raman spectroscopy, thermogravimetric analysis, pore structure measurements, and UV–vis spectroscopy were performed to investigate the morphology, structure, texture, thermal stability and linear optical properties of the ORMOSIL gel glasses. The guest two-dimensional GO/Au NP hybrids maintained their own structures during the sol–gel procedure, confirming that the sol–gel technique can effectively produce graphene-based solid-state bulky composites. Increasing doping level would result in the formation of a highly porous structure, better thermal stability, and lower linear transmittance. The nonlinear optical (NLO) properties of GO/metal NP-doped ORMOSIL gel glasses were investigated using a nanosecond open-aperture Z-scan technique at 532nm. The nonlinear absorption coefficient of GO/Au NP-doped ORMOSIL gel glasses increases from 3.79cm/GW to 8.79cm/GW with increased doping level from 4.8×10−3 to 19.2×10−3. The result demonstrates that the NLO performance of the composite ORMOSIL gel glasses can be optimized by tuning the doping level of 2D GO/Au NP sheet in the matrices of the host gel glasses. The NLO behavior of GO/Au NP-doped ORMOSIL gel glasses were attributed to the combination of nonlinear absorption and nonlinear scattering.

Ultrafast third-order nonlinear optical properties of graphene in aqueous solution and polyvinyl alcohol film

The ultrafast third-order nonlinear optical properties of graphene in both suspension and film status are studied using femtosecond time resolved optical Kerr gate technique at 800nm. The third-order nonlinear optical susceptibility is 4.2×10−14esu for solution of 0.010mg/ml. The corresponding second-order hyperpolarizability is 3.4×10−32esu per carbon atom in graphene, which is the largest among the carbon family. The graphene embed in the polymer matrix of polyvinyl alcohol film (OD=0.43) exhibits strong ultrafast nonlinear optical response of 3.3×10−12esu and shows its potential application in nonlinear optics.

(Invited) Nonlinear Optical Properties of Graphene

not Available.