Ultrafast optical dynamics in VO 2

Lysenko, Sergiy; Vikhnin, V. S.; Zhang, G.; Rúa, Armando; Fernández, Félix E.; Liu, H.

doi:10.1117/12.658811

Cited by 4 publications

(2 citation statements)

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“…Since ultrafast changes in optical properties of VO 2 have been demonstrated before, [14][15][16] it may be expected that sufficiently intense ultrashort light pulses can be similarly used to access different "states" of the material. However, the time evolution of the material's response will be more complex in this case, as is known from previous work with VO 2 , 17 and relaxation to a thermally determined condition should determine the final stable state.…”

Section: Discussionmentioning

confidence: 95%

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Coy

Cabrera

Sepúlveda

et al. 2010

Journal of Applied Physics

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Vanadium dioxide exhibits a well-known insulator-to-metal transition during which several of its physical properties change significantly. A hysteresis loop develops for each of them as the material is heated and then cooled through the transition. In this work VO 2 / SiO 2 samples were maintainedby heat sinking-at a selected temperature within the heating branch of the hysteresis loops for resistance and near-infrared transmittance, while brief thermal excursions of the VO 2 film were caused by either voltage pulses applied to the film or laser light pulses irradiating the film. These pulses had durations from milliseconds to a few seconds and the resulting drops in resistance or transmittance were easily and repeatably measurable without appreciably affecting their new values. A sequence of equal-duration pulses ͑for either equal-voltage or equal-irradiation pulses͒ caused the resistance and infrared transmittance to continue to drop, each time by a smaller amount, and larger energy pulses were required in order to cause drops comparable with the initial one. The ability of the film to change the values of the measurands in this manner with additional pulses was maintained up to a limit defined by the outer hysteresis curve for the measurand in question. The results presented show that a plurality of memory "states" in VO 2 can be established or "written" either by voltage pulses or by light pulses applied to the material, and queried or "read" by resistance or transmittance readings, or both. These states were found to remain stable for at least several hours, as long as temperature was kept constant, and are expected to persist indefinitely under this condition. In the all-optical case, if the same light beam is used for writing and reading the memory state, the device is an optical analog of a memristor.

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Section: Discussionmentioning

confidence: 95%

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Coy

Cabrera

Sepúlveda

et al. 2010

Journal of Applied Physics

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“…The increase of the fraction of the excited material undergoing the PIPT from 0 to 1 as the absorbed energy increases from J T to J S is related to a distribution of nucleation sites in the sample versus energy which was approximated by the Gaussian error function centered at J 0 = (J T + J S )/2, with a dispersion parameter σ 0 . Due to the various inhomogeneities in VO 2 [40][41][42] we also take into account Gaussian distributions of J T and J S with narrower dispersions σ T and σ S , respectively. Then the general expression for the strain generated upon excitation of the VO 2 in the insulating phase takes a form (see Supplementary Note 5 for details):…”

Section: Discussionmentioning

confidence: 99%

Large non-thermal contribution to picosecond strain pulse generation using the photo-induced phase transition in VO2

et al. 2020

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Picosecond strain pulses are a versatile tool for investigation of mechanical properties of meso-and nano-scale objects with high temporal and spatial resolutions. Generation of such pulses is traditionally realized via ultrafast laser excitation of a light-to-strain transducer involving thermoelastic, deformation potential, or inverse piezoelectric effects. These approaches unavoidably lead to heat dissipation and a temperature rise, which can modify delicate specimens, like biological tissues, and ultimately destroy the transducer itself limiting the amplitude of generated picosecond strain. Here we propose a non-thermal mechanism for generating picosecond strain pulses via ultrafast photo-induced first-order phase transitions (PIPTs). We perform experiments on vanadium dioxide VO 2 films, which exhibit a firstorder PIPT accompanied by a lattice change. We demonstrate that during femtosecond optical excitation of VO 2 the PIPT alone contributes to ultrafast expansion of this material as large as 0.45%, which is not accompanied by heat dissipation, and, for excitation density of 8 mJ cm −2 , exceeds the contribution from thermoelastic effect by a factor of five.

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Optical nonlinearity and structural dynamics of VO2 films

Lysenko¹,

Rúa²,

Fernández³

et al. 2009

Journal of Applied Physics

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The degenerate-four-wave-mixing, ultrafast optical pump-probe reflection, and scattering techniques were applied to study the nonlinear optical properties of VO2 in insulating and metallic phases. The third-order nonlinear susceptibility was measured for thin films at different excitation regimes. The VO2 recovery dynamics after light-induced phase transition (PT) shows strong sensitivity to optical pump energy and could be governed by pure electronic relaxation excluding thermal contribution at sufficiently low excitation. Increased light scattering during thermally and light-induced PT demonstrates significant VO2 heterogeneity which appears as a coexistence of insulating and metallic phases accompanied by fluctuations of dielectric constants. Different desorption activity was monitored for insulating and metallic VO2 thin solid films under femtosecond optical excitation.

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Ultrafast optical dynamics in VO 2

Cited by 4 publications

References 0 publications

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Large non-thermal contribution to picosecond strain pulse generation using the photo-induced phase transition in VO2

Optical nonlinearity and structural dynamics of VO2 films

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