Generation of half-integer harmonics and efficient THz-to-visible frequency conversion in strained graphene

Ornigotti, Marco; Ornigotti, Luca; Biancalana, Fabio

doi:10.1063/5.0049678

Cited by 9 publications

(7 citation statements)

References 61 publications

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“…Rectangular graphene flakes either free [42] or subjected to planar bending [43] have been analysed in the literature. Conical graphene rings in a magnetic field have also been studied, but only in the continuum limit approximation in the vicinity of the Dirac points and very far from the vertex [44,45].…”

Section: Introductionmentioning

confidence: 99%

Quantum Revivals in Curved Graphene Nanoflakes

2022

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Graphene nanostructures have attracted a lot of attention in recent years due to their unconventional properties. We have employed Density Functional Theory to study the mechanical and electronic properties of curved graphene nanoflakes. We explore hexagonal flakes relaxed with different boundary conditions: (i) all atoms on a perfect spherical sector, (ii) only border atoms forced to be on the spherical sector, and (iii) only vertex atoms forced to be on the spherical sector. For each case, we have analysed the behaviour of curvature energy and of quantum regeneration times (classical and revival) as the spherical sector radius changes. Revival time presents in one case a divergence usually associated with a phase transition, probably caused by the pseudomagnetic field created by the curvature. This could be the first case of a phase transition in graphene nanostructures without the presence of external electric or magnetic fields.

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Section: Introductionmentioning

confidence: 99%

Quantum Revivals in Curved Graphene Nanoflakes

2022

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“…Assuming a strain profile as the one described in Ref. 33, and pictorially represented in Fig. 2, we obtain an AGF A (s) = −B y x, corresponding to a uniform magnetic field oriented perpendicular to the graphene plane, i.e., B = B ẑ.…”

Section: Bent Graphene In the Presence Of Socmentioning

confidence: 99%

“…n ∈ N 0 indicates the Landau levels in the conduction (α = 1) and valence (α = −1) band, respectively. Notice, moreover, that since the total Hamiltonian factors in spin space, there cannot be a common n = 0 Landau level, as in the case of no intrinsic SOC [33], but rather two separate levels, with spin-dependent eigenvalues E 0,β = −β(∆ I − ∆ Z ), and spin-polarized eigenstates…”

Section: A Instantaneous Eigenstates Of ĥξ Tot For Intrinsic Soc Onlymentioning

confidence: 99%

“…Following the reasoning from Ref. [33], we can calculate the instantaneous eigenstates of the equation above, which we define as |Θ ξ,α n,β (t) , for which we have |Θ ξ,α n,β (t) = |Φ ξ,α n,β (t) for the case of intrinsic SOC, and |Θ ξ,α n,β (t) = |Σ ξ,α n,β (t) for the case of Rashba coupling. To solve Eq.…”

Section: A Linear Polarisation and Sub-lattice Couplingmentioning

confidence: 99%

“…Interestingly, though, only few works investigated the effects of (pseudo)magnetic fields in the nonlinear optical response of graphene, and they have been mainly focused on estimating how the third-order nonlinear susceptibility of graphene depends on the applied magnetic field, in the limit of strong magnetic field [32]. In a recent work, moreover, the role of a constant, out-of-plane magnetic field in the nonlinear response of graphene has been thoroughly investigated, revealing the possiblity to use the magnetic field strength to control the frequency conversion, up to the visible range [33]. None of them, though, investigated the role SOC might have in shaping the nonlinear optical response of graphene, and, more generally, 2D materials.…”

Section: Introductionmentioning

confidence: 99%

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Harmonic generation in bent graphene with artificially-enhanced spin-orbit coupling

Nieminen¹,

Ornigotti²

2022

Preprint

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We theoretically investigate the nonlinear response of bent graphene, in the presence of artificiallyenhanced spin-orbit coupling, which can occur either via adatom deposition, or by placing the sheet of bent graphene in contact with a spin-orbit active substrate. We discuss the interplay between the spin-orbit coupling and the artificial magnetic field generated by the bending, for both the cases of Rashba and intrinsic spin-orbit coupling. For the latter, we introduce a spin-field interaction Hamiltonian addressing directly the electron spin as a degree of freedom. Our findings reveal that in this case, by controlling the amount of spin-orbit coupling, it is possible to significantly tune the spectrum of the nonlinear signal, achieving, in principle, efficient conversion of light from THz to UV region.

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Nonlinear optics in graphene: theoretical background and recent advances

2023

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We present a comprehensive review of the optical response of graphene, in both the linear and nonlinear regime. This will serve as a reference for both beginners and more experienced researchers in the field. We introduce, derive, and extensively discuss the Dirac–Bloch equations framework, central to describing electron–photon interaction in nonperturbative, gapless materials. We use this model to re-derive several known results in the linear regime, such as the universal absorption law, and to describe the nonlinear interaction of ultrashort pulses with graphene. We compare the validity of the Dirac–Bloch equations model with the traditional Semiconductor-Bloch equations and point out advantages and shortcomings of the two models. Lastly, we present a cutting-edge model for describing the nonlinear optical response of graphene when bending becomes important, a situation that deeply affects the output spectra, and can provide insight to a novel, effective way to manipulate light in two-dimensional media.

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Generation of half-integer harmonics and efficient THz-to-visible frequency conversion in strained graphene

Cited by 9 publications

References 61 publications

Quantum Revivals in Curved Graphene Nanoflakes

Quantum Revivals in Curved Graphene Nanoflakes

Harmonic generation in bent graphene with artificially-enhanced spin-orbit coupling

Nonlinear optics in graphene: theoretical background and recent advances

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