Demystifying the Nonlinear-Optical Physics of Graphene

Vermeulen, Nathalie; Castelló‐Lurbe, David; Khoder, Mulham; Pasternak, Iwona; Krajewska, Aleksandra; Ciuk, Tymoteusz; Strupiński, Włodek; Cheng, Jinluo; Thienpont, Hugo; Erps, Jürgen Van

doi:10.1364/nlo.2019.nf1a.3

Cited by 15 publications

(38 citation statements)

References 6 publications

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“…We derive an expression that links the conductivity change with the commonly used effective nonlinear index n 2, gr and with the free‐carrier refraction (FCR) coefficient σ FCR introduced in ref. [12]. Finally, we showcase the validity of our formalism for a wide variety of experiments in free space and in waveguides.…”

Section: Introductionmentioning

confidence: 79%

“…The research results reported since then seem to point in different directions, and have made it a major challenge to fully understand graphene's nonlinear‐optical behavior. The experimental data include both positive‐ [ 4,9 ] and negative‐valued [ 6–8,12 ] effective nonlinearities with a magnitude compatible with that of Hendry's experiments, [ 3 ] as well as much smaller nonlinearities. [ 10 ] From the theory point of view, calculations for the perturbative nonlinearity

χ_{gr}^{false(3 false)}

[ 1,2 ] give rise to nonlinearities that are two orders of magnitude smaller than

false| χ_{normalgr}^{(3)} false| \approx 10^{- 7} esu

measured in the aforementioned experiments.…”

Section: Introductionmentioning

confidence: 84%

“…Over the past decade there has been a rapidly growing interest in the theoretical [ 1,2 ] and experimental [ 3–13 ] investigation of nonlinear‐optical refraction in graphene using free‐space and waveguided excitation configurations. This new research field was pioneered by the experiments of Hendry et al.…”

Section: Introductionmentioning

confidence: 99%

“…[ 13 ] These changes will be time‐ and space‐dependent when dealing with propagating excitation pulses. What is more, our recent investigations on the evolution of the spectral bandwidth of pulses propagating in graphene‐covered waveguides [ 12 ] have shown the need for a nonperturbative treatment of graphene's nonlinear‐optical refraction, with saturation playing an important role in the carrier dynamics. For telecom excitation wavelengths, we observed that this “saturable photoexcited carrier refraction” yields a strong, negative nonlinearity from a phenomenological point of view, [ 12 ] but we did not yet present a mathematical description for the refraction efficiency as a function of more fundamental properties of graphene.…”

Section: Introductionmentioning

confidence: 99%

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Predicting Graphene's Nonlinear‐Optical Refractive Response for Propagating Pulses

Castelló‐Lurbe

Thienpont

Vermeulen

2020

Laser & Photonics Reviews

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Nonlinear‐optical refraction is typically described by means of perturbation theory near the material's equilibrium state. Graphene, however, can easily move far away from its equilibrium state upon optical pumping, yielding strong nonlinear responses that cannot be modeled as mere perturbations. So far, one is still lacking the required theoretical expressions to make predictions for these complex nonlinear effects and to account for their evolution in time and space. Here, this long‐standing issue is solved by the derivation of population‐recipe‐based expressions for graphene's nonperturbative nonlinearities. The presented framework successfully predicts and explains the various nonlinearity magnitudes and signs observed for graphene over the past decade, while also being compatible with the nonlinear pulse propagation formalism commonly used for waveguides.

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Section: Introductionmentioning

confidence: 79%

χ_{gr}^{false(3 false)}

[ 1,2 ] give rise to nonlinearities that are two orders of magnitude smaller than

false| χ_{normalgr}^{(3)} false| \approx 10^{- 7} esu

measured in the aforementioned experiments.…”

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Predicting Graphene's Nonlinear‐Optical Refractive Response for Propagating Pulses

Castelló‐Lurbe

Thienpont

Vermeulen

2020

Laser & Photonics Reviews

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“…These predictions were inspired by the unique band structure of graphene: absence of a bandgap and linear energy–momentum dispersion for its electrons . A plethora of strong nonlinear effects in graphene in the IR and optical frequency ranges, originating from interband electron dynamics, was successfully demonstrated, including saturable absorption and nonlinear refraction, higher‐harmonic generation, and wave‐mixing processes (see also reviews). At THz frequencies, however, until recently only saturable absorption effects in doped graphene, and induced multiphoton‐like absorption in multilayer near‐intrinsic graphene were successfully demonstrated .…”

Section: Introductionmentioning

confidence: 99%

Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation

Hafez

Kovalev

Tielrooij

et al. 2019

Advanced Optical Materials

118

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visible light frequencies, corresponding to interband transitions leading to electron-hole pair generation. [5,6,12] In the case of doped graphene, that is, graphene containing a certain concentration of free electrons or holes, Drude-like conductivity was observed at far-infrared and terahertz (THz) frequencies, corresponding to intraband free-carrier absorption. [8,9,[12][13][14][15] Further, theoretical studies predicted strong nonlinear interaction of graphene with intense light fields, in particular at the technologically important THz frequencies (typically, in the range 0.1-10 THz), [16][17][18][19][20][21][22][23][24][25] as originating from both interband and intraband electron dynamics. These predictions were inspired by the unique band structure of graphene: absence of a bandgap and linear energy-momentum dispersion for its electrons. [2,3,[26][27][28] A plethora of strong nonlinear effects in graphene in the IR and optical frequency ranges, originating from interband electron dynamics, was successfully demonstrated, including saturable absorption and nonlinear refraction, [29][30][31][32][33][34][35][36][37][38][39] higherharmonic generation, [40][41][42][43][44][45][46][47] and wave-mixing processes [48][49][50] (see also reviews [51][52][53] ). At THz frequencies, however, until recently only saturable absorption effects in doped graphene, [54][55][56][57][58][59][60][61] and induced multiphoton-like absorption in multilayer near-intrinsic graphene were successfully demonstrated. [62] At the same time, the observation of the long sought-after effect of THz higher-order harmonics generation, Graphene has long been predicted to show exceptional nonlinear optical properties, especially in the technologically important terahertz (THz) frequency range. Recent experiments have shown that this atomically thin material indeed exhibits possibly the largest nonlinear coefficients of any material known to date, paving the way for practical graphene-based applications in ultrafast (opto-)electronics operating at THz rates. Here the advances in the booming field of nonlinear THz optics of graphene are reported, and the state-of-the-art understanding of the nature of the nonlinear interaction of graphene with the THz fields based on the thermodynamic model of electron transport in graphene is described. A comparison between different mechanisms of nonlinear interaction of graphene with light fields in THz, infrared, and visible frequency ranges is also provided. Finally, the perspectives for the expected technological applications of graphene based on its extraordinary THz nonlinear properties are summarized. This report covers the evolution of the field of THz nonlinear optics of graphene from the very pioneering to the state-of-the-art works. It also serves as a concise overview of the current understanding of THz nonlinear optics of graphene and as a compact reference for researchers entering the field, as well as for the technology developers.

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Nonlinear Optics with 2D Layered Materials

et al. 2018

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2D layered materials (2DLMs) are a subject of intense research for a wide variety of applications (e.g., electronics, photonics, and optoelectronics) due to their unique physical properties. Most recently, increasing research efforts on 2DLMs are projected toward the nonlinear optical properties of 2DLMs, which are not only fascinating from the fundamental science point of view but also intriguing for various potential applications. Here, the current state of the art in the field of nonlinear optics based on 2DLMs and their hybrid structures (e.g., mixed-dimensional heterostructures, plasmonic structures, and silicon/fiber integrated structures) is reviewed. Several potential perspectives and possible future research directions of these promising nanomaterials for nonlinear optics are also presented.

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Demystifying the Nonlinear-Optical Physics of Graphene

Cited by 15 publications

References 6 publications

Predicting Graphene's Nonlinear‐Optical Refractive Response for Propagating Pulses

Predicting Graphene's Nonlinear‐Optical Refractive Response for Propagating Pulses

Terahertz Nonlinear Optics of Graphene: From Saturable Absorption to High‐Harmonics Generation

Nonlinear Optics with 2D Layered Materials

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