Fibre-optical analogue of the event horizon

黑洞就像时空河流：它们弯曲的几何形状可以被看作是空间中一个运动的介质冲向黑洞的奇点。时空之河的流动速度超过光速，以至于没有任何东西可以逃脱。我们计划为光纤中的光创造一个类似的情况，在那里我们将能够探测视界的量子效应，特别是从它们作为量子真空的虚拟存在中产生光子对。这样的虚光子在视界处被分离，因此被迫在斯蒂芬·霍金首先预测的辐射过程中实现。我们的建议，雄心勃勃和冒险，但我们相信可行的，是使用光脉冲作为移动介质，因为光可以很容易地赶上光，光可以在非线性光学领域对光起作用。特别是，我们将利用这样一个事实，即在现代光子晶体光纤中，一种偏振的光脉冲与另一种偏振的光充分强烈地相互作用，建立了一种运动介质，时空河流的光学模拟。

Black holes are like space-time rivers: their curved geometry can be viewed as if space where a moving medium rushing towards the singularities of the holes. Horizons are formed where the flow speed of the space-time river exceeds the speed of light such that nothing can escape anymore. We plan to create a similar situation for light in optical fibres where we will be capable of probing the quantum effects of horizons, in particular the generation of pairs of photons from their virtual existence as the quantum vacuum. Such virtual photons are separated at the horizons and hence forced to materialize in a radiative process first predicted by Stephen Hawking. Our proposal, ambitious and adventurous, but we believe feasible, is to use pulses of light as the moving medium, because light can easily catch up with light and light can act upon light in the regime of nonlinear optics. In particular, we will exploit the fact that in modern photonic-crystal fibres light pulses of one polarization interact sufficiently strongly with light of the other polarization, establishing a moving medium, the optical analogue of the space-time river.