Second Harmonic Generation in WSe
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Ribeiro-Soares, J.; Janisch, Corey; Liu, Z; Elías, Ana Laura; Dresselhaus, M. S.; Terrones, Mauricio; Cançado, Luiz Gustavo; Jório, Ado

doi:10.1088/2053-1583/2/4/045015

Cited by 99 publications

(59 citation statements)

References 30 publications

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“…The MoS 2 measurements are in excellent agreement with refs 27 and 28, which provides support for our d s 1T′ MoTe 2 values. It is important to note that the d s values reported in refs 29, 30, and 32 are an order of magnitude larger compared to refs 27 and 28 because different calibration procedures were used. Unlike the resonance for MoS 2 , 1T′ MoTe 2 shows d s increases as the excitation wavelength increases as expected given the electronic states at ≈1 eV at the Γ point.…”

Section: Resultsmentioning

confidence: 90%

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering

et al. 2016

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We study the crystal symmetry of few-layer 1T′ MoTe2 using the polarization dependence of the second harmonic generation (SHG) and Raman scattering. Bulk 1T′ MoTe2 is known to be inversion symmetric; however, we find that the inversion symmetry is broken for finite crystals with even numbers of layers, resulting in strong SHG comparable to other transition-metal dichalcogenides. Group theory analysis of the polarization dependence of the Raman signals allows for the definitive assignment of all the Raman modes in 1T′ MoTe2 and clears up a discrepancy in the literature. The Raman results were also compared with density functional theory simulations and are in excellent agreement with the layer-dependent variations of the Raman modes. The experimental measurements also determine the relationship between the crystal axes and the polarization dependence of the SHG and Raman scattering, which now allows the anisotropy of polarized SHG or Raman signal to independently determine the crystal orientation.

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Section: Resultsmentioning

confidence: 90%

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering

et al. 2016

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“…34 Since then, both the experiments and calculations indicated that A and B exciton could also enhance SHG. 48,57,59,61,65,66,146,147 Typically, Wang et al recorded an enhancement up to three order of magnitude at A (1s) and B (1s) exciton resonance of WSe 2 at 4 K ( Figure 4A). 66 Janisch et al calculated χ (2) of WS 2 in the range of 0.5 to 2.5 eV, and the excitonic-enhanced nonlinear susceptibility was well resolved ( Figure 4B).…”

Section: Excitonic Effect-modulated Nlomentioning

confidence: 96%

“…Malard et al observed that χ (2) was enhanced for about four times when SHG energy was in resonance with the C exciton of MoS 2 . Since then, both the experiments and calculations indicated that A and B exciton could also enhance SHG . Typically, Wang et al recorded an enhancement up to three order of magnitude at A (1 s ) and B (1 s ) exciton resonance of WSe 2 at 4 K (Figure A) .…”

Section: Modulation and Enhancement Of Nlomentioning

confidence: 96%

“…SHG of the bulk MoS 2 is very weak and χ (2) is around 10 −14 m/V; however, three groups simultaneously reported that SHG of monolayer MoS 2 , WS 2 , and WSe 2 increased dramatically . Later, numerous SHG studies were conducted on MoS 2 , WS 2 , WSe 2 , MoSe 2 , and MoTe 2 , and χ (2) was reported on the order of magnitude of 1 nm/V, which is much higher than the most used commercial nonlinear crystals (eg, χ (2) of BBO, KTP, and LiNbO 3 are on the order of magnitude of pm/V). The large nonlinear susceptibility of monolayer compared with bulk is ascribed to the inversion symmetry breaking.…”

Section: Nlo Processes In Tmdsmentioning

confidence: 99%

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Nonlinear optics of two‐dimensional transition metal dichalcogenides

Wen

Gong

2019

InfoMat

180

156

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Nonlinear optics (NLO) of transition metal dichalcogenides (TMDs) is promising for the on‐chip photonic and optoelectronic applications. In this review, we will survey the current progress of NLO in TMDs. First, we will brief the basic theory of the NLO in TMDs. Second, several important nonlinear processes in TMDs such as harmonic generation, four‐wave mixing, saturable absorption, and two‐photon absorption will be presented and their potential applications are also discussed. Third, the main strategies to tune, modulate, and enhance the NLO in TMDs are reviewed, including the excitonic effect, symmetry modulation, optical cavity enhancement, valley selection, edge state, and material phase. Finally, we give an outlook regarding some important issues and directions of NLO in TMDs.

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“…Different non-linear optical phenomena like second-, third-harmonic generation and four wave mixing (FWM) [5][6][7] can be quite strong in these materials [8][9][10][11][12][13][14][15]. However, the interpretation of the nonlinear optical response is strongly affected by electronic and phonon resonances [16][17][18][19], therefore the knowledge of the interplay between these resonances is desirable.…”

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confidence: 99%

Anomalous Nonlinear Optical Response of Graphene Near Phonon Resonances

et al. 2017

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In this work we probe the third-order non-linear optical property of graphene, hexagonal boron nitride and their heterostructure by the use of coherent anti-Stokes Raman Spectroscopy. When the energy difference of the two input fields match the phonon energy, the anti-Stokes emission intensity is enhanced in h-BN, as usually expected while for graphene a anomalous decrease is observed. This behaviour can be understood in terms of q coupling between the electronic continuum and a discrete phonon state. We have also measured a graphene/h-BN heterostructure and demonstrate that the anomalous effect in graphene dominates the heterostructure optical response.Two-dimensional materials like graphene, hexagonal boron nitride (h-BN) and heterostructures exibit novel physical properties and promisses different applications in electronics and photonics [1][2][3][4]. Different non-linear optical phenomena like second-, third-harmonic generation and four wave mixing (FWM) [5][6][7] can be quite strong in these materials [8][9][10][11][12][13][14][15]. However, the interpretation of the nonlinear optical response is strongly affected by electronic and phonon resonances [16][17][18][19], therefore the knowledge of the interplay between these resonances is desirable.Here we measured the third order optical emission by the degenerated four wave mixing emission of graphene, h-BN and their heterostructure near phonon resonances. We show that while the FWM signal in h-BN shows the expected enhancement, in graphene the signal is decreased exactly at the phonon resonance. These results are explained in terms of interference effects between the electronic continuum and discrete phonon states for these two different materials. We also show that this unusual effect in graphene dominates the optical response in the graphene/h-BN heterostructure.Four wave mixing is a third-order non-linear optical phenomena, where three frequencies are combined to generate a forth [7]. In this work we are restricted to the case of degenerate FWM, where two photons of frequency ω 1 combines with a photon of ω 2 at the material and generate the emission of another photon with frequency ω 4 . The energy conservation in this case is given by ω 4 = 2 ω 1 − ω 2 . Hendry et al. [8] have measured the FWM intensity in graphene as a function of the pump laser energy and its third order optical non linear optical property was characterized. Also different theoretical works have calculated the third-order optical conductivity of graphene [20][21][22][23], showing the importance of different physical quantities like Fermi energy or temperature. However these works did not treat the problem of the third order optical nonlinearity near phonon resonances. The so-called coherent anti-Stokes Raman spectroscopy (CARS) is a special case of FWM when the energy difference between ω 1 and ω 2 matches a phonon energy ( ω ph ), then ω 4 corresponds exactly to the anti-Stokes frequency in Raman scattering. In general, when the energy condition ω 1 − ω 2 = ω ph is satisfied, the ω ...

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Second Harmonic Generation in WSe ₂

Cited by 99 publications

References 30 publications

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering

Nonlinear optics of two‐dimensional transition metal dichalcogenides

Anomalous Nonlinear Optical Response of Graphene Near Phonon Resonances

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Second Harmonic Generation in WSe 2

Cited by 99 publications

References 30 publications

Characterization of Few-Layer 1T′ MoTe2 by Polarization-Resolved Second Harmonic Generation and Raman Scattering

Characterization of Few-Layer 1T′ MoTe2 by Polarization-Resolved Second Harmonic Generation and Raman Scattering

Nonlinear optics of two‐dimensional transition metal dichalcogenides

Anomalous Nonlinear Optical Response of Graphene Near Phonon Resonances

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Product

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Second Harmonic Generation in WSe ₂

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering

Characterization of Few-Layer 1T′ MoTe₂ by Polarization-Resolved Second Harmonic Generation and Raman Scattering