Extremely nonlinear nano-modified liquid and liquid crystal optical meta-materials

We present an overview of nano-dispersed nonlinear organic liquids and liquid crystals and several nonlinear optical processes enabled by these extremely nonlinear optical metamaterials. In particular, we have developed a neat organic liquid that possess extraordinarily large femtoseconds-, picoseconds-, and nanoseconds- nonlinear multiphoton absorption properties well suited for optical limiting applications [1, 2]. Using this liquid as the wave-guiding core in fiber arrays, we have developed wide field of view imaging faceplate that could also act as passive sensor protection devices against visible pulsed lasers in the femtoseconds - nanoseconds time scale. Recent experiments have also confirmed that gold nano-spheres doped neat nonlinear liquids could extend the bandwidth of efficient all-optical switching operation from the visible to near infrared regime, and for time scales ranging through the microseconds to cw regime [3]. In organic liquids that exhibit nematic liquid crystal phases, incorporation of similar nano-particulate creates extraordinarily nonlinear optical meta-materials capable of efficient all-optical switching capabilities for microseconds - cw lasers [4]. Metamaterials fabricated with core-shell nano-spheres dispersed nematic liquid crystals could exhibit effective refractive indices that are tunable from negative through zero to positive values; more recently, we have demonstrated that incorporating nematic liquid crystals in nano-structures could also give rise to similar tunable refractive index ranging from positive through zero and negative values [5-7]. In this presentation, we will discuss the fundamental molecular optical physics involved in the liquid and the liquid crystalline materials, and the electrodynamics of meta-materials formed by dispersing nano-particulates in the liquid crystal media. Experimental observations of nonlinear transmissions for femtoseocnds-, picoseconds, nanoseconds, microseconds, and cw lasers will be demonstrated, along with the theoretical modeling results taking into account complex interplay between the molecular photonic transitions and the optical intensity's spatio-temporal evolution. We will also detailed the 'intensity dependent Jones Matrix' theory of all-optical switching in twistalignment nano-particulate doped nematic liquid crystal) films, in conjunction with experimental observations of ultrafast [for liquid crystalline materials] all-optical switching made possible by laser induced order parameter modifications in these films. In particular, we have demonstrated microseconds switching speed with low power (mW) lasers in the visible as well as near infrared regime. Extinction ratio exceeding 103 can be obtained. Since the underlying mechanisms hold throughout the entire visible-infrared spectrum [8], one could realize extremely broadband all-optical switches using these liquid crystal films.