Wednesday, January 04, 2012

Temporal Cloaking

OK, we have had cloaking of objects using these matematerials. Now along comes an experimental demonstration of not spatial cloaking, but temporal cloaking[1]!

Abstract: Recent research has uncovered a remarkable ability to manipulate and control electromagnetic fields to produce effects such as perfect imaging and spatial cloaking. To achieve spatial cloaking, the index of refraction is manipulated to flow light from a probe around an object in such a way that a ‘hole’ in space is created, and the object remains hidden. Alternatively, it may be desirable to cloak the occurrence of an event over a finite time period, and the idea of temporal cloaking has been proposed in which the dispersion of the material is manipulated in time, producing a ‘time hole’ in the probe beam to hide the occurrence of the event from the observer. This approach is based on accelerating the front part of a probe light beam and slowing down its rear part to create a well controlled temporal gap—inside which an event occurs—such that the probe beam is not modified in any way by the event. The probe beam is then restored to its original form by the reverse manipulation of the dispersion. Here we present an experimental demonstration of temporal cloaking in an optical fibre-based system by applying concepts from the space–time duality between diffraction and dispersive broadening. We characterize the performance of our temporal cloak by detecting the spectral modification of a probe beam due to an optical interaction and show that the amplitude of the event (at the picosecond timescale) is reduced by more than an order of magnitude when the cloak is turned on. These results are a significant step towards the development of full spatio-temporal cloaking.

There is also a News and Views article on this work in the same issue of Nature.

I'm still reading this, but thought those who have access to Nature might want to looking into it. Fascinating work!

Zz.

[1] M. Fridman et al., Nature v.481, p.62 (2012).

1 comment:

Logan Wright said...

This is one of many really "wow" phenomena that is enabled by the space-time duality approach! Similar ideas have been used (many by the same group, even!) to construct time lenses that allow for "all-optical oscilloscopes for light" and, my personal favourite, frequency magnification. It is just too bad that most (popular) coverage has missed out on the fundamental limitations of this; while it can definitely be used to hide say, a bit stream in a fiber optic communication, it could never be used to hide a diamond robbery (at least unless it was a very strange robbery indeed!)

For the non-subscribed, the Arxiv link: http://arxiv.org/abs/1107.2062