Waveguide arrays with spatially inhomogeneous nonlinearity

在本研究计画中，我们将探讨光波在一维光子晶格（波导阵列）中的传播，这些光子晶格具有非均匀或调制的有效非线性分布。尽管最近发表了大量的理论工作，其动机是与其他波系统（例如超冷量子气体）的密切类比，但实际上迄今为止还没有对这个有吸引力的方向进行实验研究，仅仅是因为缺少合适的实验模型系统。在光折变锂离子光波导阵列中，可以通过局域扩散处理来改变单通道空间尺度上的非线性效应。在这样的系统中，我们计划研究实验非线性波现象，如不稳定性，布洛赫振荡，法诺共振或不同种类的孤子的存在，支持这些效果的理论建模和模拟。

In this research project we will investigate optical wave propagation in one-dimensional photonic lattices (waveguide arrays) having an inhomogeneous or modulated distribution of the effective nonlinearity. Although a large number of theoretical works have been recently published, motivated by the close analogies to other wave systems like e.g. ultra-cold quantum gases, in fact no experimental investigation of this attractive direction has been performed so far, simply because a suitable experimental model system was missing. In photorefractive lithium niobate waveguide arrays we can use local diffusion treatment to modify the size of the nonlinearity on the spatial scale of single channels. In such systems we plan to investigate experimentally nonlinear wave phenomena like instabilities, Bloch oscillations, Fano resonances or the existence of different kinds of solitons, supported by theoretical modelling and simulations of these effects.