Plasmonic enhancement of the vanadium dioxide phase transition induced by low-power laser irradiation

Abstract

Nanocomposites consisting of gold nanoparticle (NP) arrays and vanadium dioxide (VO 2 ) thin films are noteworthy for the tunability of both their thermal and optical properties. The localized surface plasmon resonance (LSPR) of the Au can be tuned when its dielectric environment is modulated by the semiconducting-to-metal phase transition (SMT) of the VO 2 ; the LSPR itself can be altered by changing the shape of the NPs and the pitch of the NP array. In principle, then it should be possible to choose a combination of VO 2 film and Au LSPR properties that maximizes the overall optical response of the nanocomposite. To demonstrate this effect, transient transmission measurements were conducted on lithographically fabricated arrays of Au NPs of diameter 140 nm, array spacing 350 nm, and covered with a 60 nm thick films of VO 2 via pulsed laser deposition. Both Au::VO 2 nanocomposites and bare VO 2 film were irradiated with a shuttered 785 nm pump laser, and their optical response was probed at 1550 nm by a fixed-frequency diode laser. The Au::VO 2 nanocomposite exhibited an increased effective absorption coefficient 1.5 times that of the plain film and required 37 % less laser power to induce the SMT. The time-dependent temperature rise in the film as a function of laser intensity was calculated from these measurements and compared with both analytic and finite-element models. Our results suggest that Au::VO 2 nanocomposites

Manipulating metal–insulator transitions of VO2 films via embedding Ag nanonet arrays*

“…Au and Ag), [21][22][23][24] external photon injection brings the resonant absorption of energy, consequently reducing the T c . [25][26][27] Until now, most research attached importance to the external stimulus of light for the T c tuning, [26][27][28] considering that the MIT nature of metal nanoparticles/VO 2 system in a lightless environment has as yet received little study. In spite of its importance, however, the underlying physical mechanisms to drive MIT when metal nanoparticles are involved are not well understood.…”

Plasmonic Probe of the Semiconductor to Metal Phase Transition in Vanadium Dioxide

“…18 Most previous studies of Au::VO 2 structures have focused on modulated or enhanced absorption of macroscale films for applications ranging from optical switches to "smart" window coatings over a broad range of frequencies and employing a variety of nanostructures. 2,4,[6][7][8][9][10][11][12][13][14]19,20 However, Au::VO 2 nanocomposites also present an opportunity to probe the fundamental physics of the SMT at the nanoscale. If the sizes of the Au nanostructures are close to those of the VO 2 grains within the nanocomposite, the metal nanostructure can function as a nanoantenna, 21 transmitting information into the far field about the several VO 2 grains located within the plasmon near field.…”

“…Nanocomposites consisting of noble metal nanostructures and metal oxides with solid–solid phase transitions have garnered much attention in recent years as a class of active plasmonic metamaterials. − When the phase transition modulates the optical properties of the metal oxide in the vicinity of the localized surface-plasmon resonance (LSPR) of the metal, it can lead to a shift in resonance spanning hundreds of nanometers in wavelength. − In nanocomposites consisting of vanadium dioxide (VO 2 ) films and gold nanostructures, the semiconductor-to-metal phase transition (SMT) of the VO 2 leads to plasmon-enhanced absorption − that can be tuned thermally, optically, electrically, or mechanically . Most previous studies of Au::VO 2 structures have focused on modulated or enhanced absorption of macroscale films for applications ranging from optical switches to “smart” window coatings over a broad range of frequencies and employing a variety of nanostructures. ,,− ,, However, Au::VO 2 nanocomposites also present an opportunity to probe the fundamental physics of the SMT at the nanoscale. If the sizes of the Au nanostructures are close to those of the VO 2 grains within the nanocomposite, the metal nanostructure can function as a nanoantenna, transmitting information into the far field about the several VO 2 grains located within the plasmon near field. , …”