Modulating Light by Metal Nanospheres-Embedded PZT Thin-Film

Abstract

We calculated the optical contrast of silver nanospheres embedded in a lead-zirconate-titanate (PZT) film in relation to various volumetric concentrations (<5%) of the nanospheres using Mie theory to approximate the extinction spectra, after assuming PZT to be isotropic. Then, we determined the nanosphere radius for large shifts in extinction efficiency that yields high contrast (as high as 12.74 dB), this radius was 7.4 nm. A device based on this nanocomposite film will be able to modulate light in the visible spectrum with sharp contrast between its "on" and "off" state at high speed and with low power consumption.

Modulated retro reflector for VLC applications

“…The refrective indices of Ag, PZT and Si were taken from 33,34 . Note that in our previous work we showed that solid Ag nano-spheres with diameter of ~15nm embedded in PZT yield the largest extinction cross-section at an incident wavelength of 575nm 11,12 . Figure 3 depicts the transmittance of a 500nm thick nanocomposite film embedded with Ag nano-shells with inner and outer diameter of 4 and 40nm, respectively.…”

Tunable electro-optic filter based on metal-ferroelectric nanocomposite for VLC

“…However, Mie theory provides an exact solution to spherically symmetric particles in an isotropic medium, whereas ferroelectric materials are anisotropic and their permittivity is a diagonal second rank tensor. Therefore, the Mie model can only provide an approximation in the case of weak anisotropic materials [15]. Ferroelectric films, such as PZT, can be a medium in which the nanoparticles are embedded, since PZT exhibits a linear electro-optic effect that can change the embedded particles with applied external field.…”

“…Hence, the tunability speed is related to the device area and to its lateral resistance. This resistance is determined by both the area and the design of the electrodes [15]. Therefore, by adopting the geometry in [15], we evaluate that the tunability speed may reach tens of MHz.…”

“…This resistance is determined by both the area and the design of the electrodes [15]. Therefore, by adopting the geometry in [15], we evaluate that the tunability speed may reach tens of MHz. Note that nonferroelectric materials exhibiting the Pockels effect may also be used as layers in the filter design, such as AlN [17].…”

“…where z is the geometrical path length of a thin film, N is the nanoparticle volumetric density in that film, and C ext is the extinction cross section of the embedded nanoparticles, which depends on the applied voltage [15]. Therefore, for a given optical density, D, the mathematical model describing the unscattered power passing through a device is given by P P 0 exp−D.…”