Fourier optics and light stopping with nonlinear fronts

在这个建议中，我们起草的路线走向实验实现不同的折射率前端诱导的光学跃迁的带边附近的周期性波导。即，考虑光停止、时间透镜和超快任意波形生成。为此，我们建议利用具有布拉格光栅的硅波导，并在带边缘附近操作它们。通过开关/泵浦脉冲的瞬时克尔效应，在同一波导中产生移动折射率波前。为了避免自由载流子产生的损失，我们计划使用中红外（MIR）辐射的泵浦pulse.The建议的效果是利用我们的小组在最近几年开发的理论概念，我们现在计划实验证明。在光停止的情况下，如在机械碰撞中，光脉冲撞击传播前沿并停止。在这里，光能可以被转移到零群速度模式，然后由具有相反斜率的第二波前释放。在所谓的光学推扫的情况下，信号脉冲被折射率前沿捕获，同时具有频率变化和压缩。正如我们最近在理论上所表明的那样，在前面的捕获相当于在传统透镜的焦平面上观察到的傅立叶光学。这种效应不仅允许脉冲压缩，而且允许从真实的到倒易空间的信息传输，反之亦然。因此，一个定义的光谱组成的信号可以被转换成一个设计的短时间脉冲，允许定制的波形generation.The拟议的系统将提供信号的时间压缩，光停止，和脉冲结构的集成光学技术。MIR泵浦脉冲的扩展允许利用具有大的非线性和强场限制的已建立的硅波导技术。

In this proposal we draft the route towards experimental realisation of different index front-induced optical transitions close to the band edge of a periodical waveguides. Namely, light stopping, time lens, and ultrafast arbitrary waveform generation are considered. For that we propose to utilise silicon waveguides with Bragg gratings and operate them close to the band edge. The moving refractive index front will be generated in the same waveguide via instantaneous Kerr effect from the copropagating switching/pump pulse. To avoid the losses via free carrier generation we plan to use mid-infrared (MIR) radiation for the pump pulse.The proposed effects are utilising the theoretical concepts developed by our group in recent year which we now plan to demonstrate experimentally. In case of light stopping, like in a mechanical collision, the light pulse hits a propagating front and stops. Here, the light energy can be transferred to the zero group velocity mode and later released by a second front with an opposite slope. In case of a so-called optical push broom, the signal pulse is trapped by the index front with a simultaneous frequency change and compression. As we have recently shown theoretically the trapping in the front is equivalent to Fourier optics observed at the focal plane of conventional lenses. This effect allows not only pulse compression but also the transfer of information from real to reciprocal space and vice versa. Thus, a defined spectral composition of the signal can be converted in a designed short temporal pulse, allowing for customizable wave form generation.The proposed system will provide signal temporal compression, light stopping, and pulse structuring in integrated optics technology. The extension to the MIR pump pulse allows utilisation of established silicon waveguide technology with large nonlinearity and strong field confinement.