Emergence of geometrical optical nonlinearities in photonic crystal fiber nanowires

Resonant, broadband and highly efficient optical frequency conversion in semiconductor nanowire gratings at visible and UV wavelengths

Using a hydrodynamic approach we examine bulk- and surface-induced second and third harmonic generation from semiconductor nanowire gratings having a resonant nonlinearity in the absorption region. We demonstrate resonant, broadband and highly efficient optical frequency conversion: contrary to conventional wisdom, we show that harmonic generation can take full advantage of resonant nonlinearities in a spectral range where nonlinear optical coefficients are boosted well beyond what is achievable in the transparent, long-wavelength, non-resonant regime. Using femtosecond pulses with approximate…

相位中断作为优化非线性光学响应的新设计范式

Phase disruption as a new design paradigm for optimizing the nonlinear-optical response

本文提出相位中断作为优化准一维结构非线性光学响应的新设计范式，通过在概率流主路径上放置短侧基或导线显著增强固有非线性，且无需端部电荷供体-受体。

Volatile optical bistability enabled by mechanical nonlinearity

Optical devices with metastable states controlled with light (optical flip-flops) are needed in data storage, signal processing and displays. Although non-volatile optical memory relying on structural phase transitions in chalcogenide glasses has been widely used for optical data storage, beyond that, weak optical nonlinearities have hindered the development of low-power bistable devices. Here we report on a new type of volatile optical bistability in a resonant hybrid nano-optomechanical device, comprising of a pair of anchored nanowires decorated with plasmonic metamolecules. The nonlinearit…

The influence of geometry and topology of quantum graphs on their nonlinear-optical properties

We analyze the nonlinear optics of quasi one-dimensional quantum graphs and manipulate their topology and geometry to generate for the first time nonlinearities in a simple system approaching the fundamental limits of the first and second hyperpolarizabilities. Changes in geometry result in smooth variations of the nonlinearities. Topological changes between geometrically-similar systems cause profound changes in the nonlinear susceptibilities that include a discontinuity due to abrupt changes in the boundary conditions. This work may inform the design of new molecules or nano- scale structure…

高效六边形纳米线MAPbI3钙钛矿太阳能电池及其宽波段光陷阱

High-Efficiency Hexagonal Nanowire MAPbI3 Perovskite Solar Cell with Broadband Light Trapping

本研究提出一种高效六边形纳米线钙钛矿太阳能电池，通过优化结构参数提升光吸收和载流子传输效率，实现24.2%的高功率转换效率。

Giant anomalous self-steepening in photonic crystal waveguides

Self-steepening of optical pulses arises due the dispersive contribution of the $χ^{(3)}(ω)$ Kerr nonlinearity. In typical structures this response is on the order of a few femtoseconds with a fixed frequency response. In contrast, the effective $χ^{(3)}$ Kerr nonlinearity in photonic crystal waveguides (PhCWGs) is largely determined by the geometrical parameters of the structure and is consequently tunable over a wide range. Here we show self-steepening based on group-velocity (group-index) modulation for the first time, giving rise to a new physical mechanism for generating this effect. Furt…