Husko Chad, Wulf Matthias, Lefrancois Simon, Combrié Sylvain, Lehoucq Gaëlle, De Rossi Alfredo, Eggleton Benjamin J, Kuipers L
Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Institute of Photonics and Optical Science (IPOS), School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia.
Center for Nanophotonics, FOM Institute AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands.
Nat Commun. 2016 Apr 15;7:11332. doi: 10.1038/ncomms11332.
Solitons are localized waves formed by a balance of focusing and defocusing effects. These nonlinear waves exist in diverse forms of matter yet exhibit similar properties including stability, periodic recurrence and particle-like trajectories. One important property is soliton fission, a process by which an energetic higher-order soliton breaks apart due to dispersive or nonlinear perturbations. Here we demonstrate through both experiment and theory that nonlinear photocarrier generation can induce soliton fission. Using near-field measurements, we directly observe the nonlinear spatial and temporal evolution of optical pulses in situ in a nanophotonic semiconductor waveguide. We develop an analytic formalism describing the free-carrier dispersion (FCD) perturbation and show the experiment exceeds the minimum threshold by an order of magnitude. We confirm these observations with a numerical nonlinear Schrödinger equation model. These results provide a fundamental explanation and physical scaling of optical pulse evolution in free-carrier media and could enable improved supercontinuum sources in gas based and integrated semiconductor waveguides.
孤子是由聚焦和散焦效应平衡形成的局域波。这些非线性波存在于多种物质形式中，但表现出相似的特性，包括稳定性、周期性重现和类粒子轨迹。一个重要特性是孤子裂变，即一个高能高阶孤子由于色散或非线性微扰而分裂的过程。在这里，我们通过实验和理论证明，非线性光生载流子的产生可以诱导孤子裂变。利用近场测量，我们直接原位观察了纳米光子半导体波导中光脉冲的非线性空间和时间演化。我们开发了一种解析形式来描述自由载流子色散（FCD）微扰，并表明实验超过最小阈值一个数量级。我们用数值非线性薛定谔方程模型证实了这些观察结果。这些结果为自由载流子介质中光脉冲演化提供了基本解释和物理标度，并有望改进基于气体和集成半导体波导的超连续谱源。
