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

The emerging technology of visible light communications (VLC) will provide a new modality of communication. This technology uses illumination lighting to carry information. We propose to add a smart capability to mitigate interferences from unwanted light sources. This is achieved by adaptively filtering interference light using a tunable filter to block interferences dynamically. In this Letter, we present an innovative concept for a tunable notch filter based on ferroelectric thin films embedded with noble metal nanoparticles. The adaptivity of the filter is achieved by controlling the external applied voltage. This voltage creates an electric field that changes the refractive index of the host film through the linear electro-optic effect. Moreover, the fundamental characteristics of the filter are determined by the layer's parameters, such as film thickness, nanoparticles concentration and geometry, and the material of both the host thin film and nanoparticles. We study the tunability of lead zirconate titanate (PZT) embedded with Ag nanoparticles that reaches approximately 50 nm, between 530 and 590 nm. Moreover, we showed that a PZT notch filter embedded with Ag nanoshells has its stop band shifted to shorter wavelengths. These tunable filters can be used as mode selectors inside a laser resonator, spatial light filters for imaging and communication both for VLC and infrared communication.