Laser excitation and excited state dynamics in vanadium dioxide thin film

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

doi:10.1016/j.jlumin.2006.01.025

Cited by 8 publications

(5 citation statements)

References 19 publications

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“…The responses observed in all cases here are due purely to thermal effects caused by the voltage or light pulses. 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: 99%

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: 99%

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Coy

Cabrera

Sepúlveda

et al. 2010

Journal of Applied Physics

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“…A light-induced PT in sufficiently thin uniform VO 2 film occurs simultaneously in entire film volume at critical excitation level, while during thermally induced PT the PT temperature range is broadened through several degrees near PT point T c = 340 K. Apparently, the driven force for light-induced and thermally induced PT is different. [16][17][18][19][20] At present, the problem related to PT dynamics of VO 2 materials, including the modification of optical nonlinear constants, transient heterogeneity, and degradation, remains open.…”

Section: Introductionmentioning

confidence: 99%

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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“…Similarly, the conductivity of Ge was varied from 1 to 4 × 10 3 S/m to simulate the influence of optical pump irradiation [ 49 , 54 ]. It is essential to mention that a 400 nm optical pump (3.1 eV) is typically used to activate the photoinduced carriers in Ge (0.66 eV), and the pump frequency enables the Ge conductivity change to 4 × 10 3 S/m that only leads to a slight alteration in undoped VO 2 conductivity, thus ensuring independence between the two modulation approaches [ 52 , 55 , 56 , 57 ]. The normalized transmission spectra were calculated via the formula: |T(ω)| = |E s (ω)/E r (ω)| with E s (ω) and E r (ω) representing the amplitude of THz waves transmitted through the device and the thickness of bare sapphire, respectively [ 58 ].…”

Section: Methodsmentioning

confidence: 99%

Multifield-Controlled Terahertz Hybrid Metasurface for Switches and Logic Operations

et al. 2022

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Terahertz (THz) meta-devices are considered to be a promising framework for constructing integrated photonic circuitry, which is significant for processing the upsurge of data brought about by next-generation telecommunications. However, present active metasurfaces are typically restricted by a single external driving field, a single modulated frequency, fixed switching speed, and deficiency in logical operation functions which prevents devices from further practical applications. Here, to overcome these limitations, we propose a hybrid THz metasurface consisting of vanadium dioxide (VO2) and germanium (Ge) that enables electrical and optical tuning methods individually or simultaneously and theoretically investigate its performance. Each of the two materials is arranged in the meta-atom to dominate the resonance strength of toroidal or magnetic dipoles. Controlled by either or both of the external excitations, the device can switch on or off at four different frequencies, possessing two temporal degrees of freedom in terms of manipulation when considering the nonvolatility of VO2 and ultrafast photogenerated carriers of Ge. Furthermore, the “AND” and “OR” logic operations are respectively achieved at two adjacent frequency bands by weighing normalized transmission amplitude. This work may provide an auspicious paradigm of THz components, such as dynamic filters, multiband switches, and logical modulators, potentially promoting the design and implementation of multifunctional electro-optical devices in future THz computing and communication.

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Laser excitation and excited state dynamics in vanadium dioxide thin film

Cited by 8 publications

References 19 publications

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Optoelectronic and all-optical multiple memory states in vanadium dioxide

Optical nonlinearity and structural dynamics of VO2 films

Multifield-Controlled Terahertz Hybrid Metasurface for Switches and Logic Operations

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