Polarization-Independent Large Third-Order-Nonlinearity of Orthogonal Nanoantennas Coupled to an Epsilon-Near-Zero Material

The nonlinear optical response of common materials is limited by bandwidth and energy consumption, which impedes practical application in all-optical signal processing, light detection, harmonic generation, etc. Additionally, the nonlinear performance is typically sensitive to polarization. To circumvent this constraint, we propose that orthogonal nanoantennas coupled to Al-doped zinc oxide (AZO) epsilon-near-zero (ENZ) material show a broadband (~1000 nm bandwidth) large optical nonlinearity simultaneously for two orthogonal polarization states. The absolute maximum value of the nonlinear refractive index n2 is 7.65 cm2∙GW−1, which is 4 orders of magnitude larger than that of the bare AZO film and 7 orders of magnitude larger than that of silica. The coupled structure not only realizes polarization independence and strong nonlinearity, but also allows the sign of the nonlinear response to be flexibly tailored. It provides a promising platform for the realization of ultracompact, low-power, and highly nonlinear all-optical devices on the nanoscale.

Curved Ballasted Track-Vehicle Dynamic Interaction: Effects of Curve Radius and Track Structural Nonlinearity

In this work, a model for characterizing the ballasted track-vehicle interaction is presented. The vehicle is modelled as a multi-rigid-body system consisting of a car body, two bogie frames and four wheelsets, and the track is modelled by finite elements including the rail, the sleeper and the track bed. All bodies are connected by spring-dashpot elements. With novelty, the geometric nonlinearity of curved rail beam and mechanical nonlinearity of ballasted bed lateral resistance have been fully considered. Besides, numerical solution procedures including iteration and increment have been also developed to accurately clarify the dynamic nonlinear performance of vehicle-track systems. Apart from model validations in statics and dynamics, the influence of track nonlinearity and curved track radius on vehicle-track dynamic performance has been revealed in detail.

Two dimensional graphene oxide films for enhanced optical nonlinear performance in CMOS compatible integrated devices

<p>We integrate GO films with silicon-on-insulator nanowires (SOI), high index doped silica glass (Hydex) and silicon nitride (SiN) waveguides and ring resonators, to demonstrate an enhanced optical nonlinearity including Kerr nonlinearity and four-wave mixing (FWM).</p>

Two dimensional graphene oxide films for enhanced optical nonlinear performance in CMOS compatible integrated devices

<p>We integrate GO films with silicon-on-insulator nanowires (SOI), high index doped silica glass (Hydex) and silicon nitride (SiN) waveguides and ring resonators, to demonstrate an enhanced optical nonlinearity including Kerr nonlinearity and four-wave mixing (FWM).</p>