标题： 二维材料和非线性光学相互作用的相干控制 显示英文标题

标题： Two-dimensional materials and the coherent control of nonlinear optical interactions

摘要： 深度亚波长的二维薄膜可能表现出极其强烈的非线性效应。 在这里，我们展示了二维薄膜具有相位可控制的非线性特性，即介质中非线性极化波的振幅可以通过泵浦光束的相位进行控制，并决定探测光束是否会“感受到”这种非线性。 这与体材料中的非线性形成鲜明对比，在体材料中，光在介质中的传播会平均掉任何这样的相位依赖性。 我们在石墨烯中进行了一系列实验，突显了光学非线性相位依赖性的一些后果，{例如} 非线性衍射光束的相干控制，单泵浦光束 {引起的} 相位共轭以及展示了一种由负反射特征的非线性镜。 观察到的相位灵敏度并不特定于石墨烯，而是仅仅由于维度性，因此预计在所有二维材料中都会出现。 显示英文摘要

摘要： Deeply sub-wavelength two-dimensional films may exhibit extraordinarily strong nonlinear effects. Here we show that 2D films exhibit the remarkable property of a phase-controllable nonlinearity, i.e., the amplitude of the nonlinear polarisation wave in the medium can be controlled via the pump beam phase and determines whether a probe beam will "feel" or not the nonlinearity. This is in stark contrast to bulk nonlinearites where propagation in the medium averages out any such phase dependence. We perform a series of experiments in graphene that highlight some of the consequences of the optical nonlinearity phase-dependence, {such as} the coherent control of nonlinearly diffracted beams, single-pump-beam {induced} phase-conjugation and the demonstration of a nonlinear mirror characterised by negative reflection. The observed phase sensitivity is not specific to graphene but rather is solely a result of the dimensionality and is therefore expected in all 2D materials.