Research on Optimization method of power flow of cylindrical shell stiffener based on BESO

In order to establish a method for topological optimization of the power flow response of a cylindrical shell stiffener structure based on BESO, this paper will combine the BESO topology optimization theoretical and the power flow response theory , and take the overall minimization of the power flow of the cylindrical shell stiffener structure as the optimization goal. Then an iterative optimization algorithm for the layout of the stiffener structure on the cylindrical shell surface can be established. The plate-beam coupling structure is used to simulate the cylindrical shell stiffener structure, a finite element model of the cylindrical shell stiffened is established and solved to obtain the power flow sensitivity of the finite element. This is used as an iterative criterion for the layout of the stiffener on the surface of the cylindrical shell structure optimize. Through the analysis of numerical examples, it is obtained that the optimization of the rib layout can better reduce the overall power flow response of the structure, which also verifies the feasibility of the optimization method.

All-optical switching of an epsilon-near-zero plasmon resonance in indium tin oxide

Nonlinear optical devices and their implementation into modern nanophotonic architectures are constrained by their usually moderate nonlinear response. Recently, epsilon-near-zero (ENZ) materials have been found to have a strong optical nonlinearity, which can be enhanced through the use of cavities or nano-structuring. Here, we study the pump dependent properties of the plasmon resonance in the ENZ region in a thin layer of indium tin oxide (ITO). Exciting this mode using the Kretschmann-Raether configuration, we study reflection switching properties of a 60 nm layer close to the resonant plasmon frequency. We demonstrate a thermal switching mechanism, which results in a shift in the plasmon resonance frequency of 20 THz for a TM pump intensity of 70 GW cm−2. For degenerate pump and probe frequencies, we highlight an additional two-beam coupling contribution, not previously isolated in ENZ nonlinear optics studies, which leads to an overall pump induced change in reflection from 1% to 45%.