Temporal Cloaking

[Aitzaz Rai]

Last year, a team led by Alexander Gaeta, an optical physicist at Cornell University in Ithaca, New York, built the first working temporal cloak by manipulating laser pulses. But the time windows opened up too rarely to be able to hide data coming in at telecommunication rates.

Splitting light
To speed up the cloaking rate, Lukens and his colleagues exploited a wave phenomenon that was first discovered by British inventor Henry Fox Talbot in 1836. When a light wave passes through a series of parallel slits called a diffraction grating, it splits apart. The rays emanating from the slits combine on the other side to create an intricate interference pattern of peaks and troughs. Talbot discovered that this pattern repeats at regular intervals, creating what is now known as a Talbot carpet. There is also a temporal version of this effect in which you manipulate light over time to generate regular periods with zero light intensity, says Lukens. Data can be then be hidden in these holes in time.



Lukens' team created its Talbot carpet in time by passing laser light through a 'phase modulator', a waveguide that also had an oscillating electrical voltage applied to it. As the voltage varied, the speed at which the light travelled through the waveguide was altered, splitting the light into its constituent frequencies and knocking these out of step. As predicted, at regular time intervals, the separate frequencies recombined destructively to generate time holes. Lukens’ team then used a second round of phase modulation to compress the energy further, expanding the duration of the time windows to 36 picoseconds (or 36 trillionths of a second).

 

[Aitzaz Rai]

British troops have been testing a Harry Potter-style ‘invisibility cloak’ that makes them disappear on the battlefield.

During field trials in the US, soldiers from 3rd Battalion The Rifles (3 Rifles) used a high-tech camouflage sheeting called Vatec that even hid them from infra-red and heat-seeking devices.

But The Mail on Sunday understands that even more radical camouflage technologies are being developed that seek to replicate how cephalopods, such as squid or octopus, blend in with their environment and avoid predators.

Their skin contains pigment- rich cells known as chromatophores that react to external factors such as the threat of a predator to change color.

Trials are successful Where a Complete Armed forces base can be camouflaged from The invaders

 

[khansaheeb]

Last year, a team led by Alexander Gaeta, an optical physicist at Cornell University in Ithaca, New York, built the first working temporal cloak by manipulating laser pulses. But the time windows opened up too rarely to be able to hide data coming in at telecommunication rates.

Splitting light
To speed up the cloaking rate, Lukens and his colleagues exploited a wave phenomenon that was first discovered by British inventor Henry Fox Talbot in 1836. When a light wave passes through a series of parallel slits called a diffraction grating, it splits apart. The rays emanating from the slits combine on the other side to create an intricate interference pattern of peaks and troughs. Talbot discovered that this pattern repeats at regular intervals, creating what is now known as a Talbot carpet. There is also a temporal version of this effect in which you manipulate light over time to generate regular periods with zero light intensity, says Lukens. Data can be then be hidden in these holes in time.



Lukens' team created its Talbot carpet in time by passing laser light through a 'phase modulator', a waveguide that also had an oscillating electrical voltage applied to it. As the voltage varied, the speed at which the light travelled through the waveguide was altered, splitting the light into its constituent frequencies and knocking these out of step. As predicted, at regular time intervals, the separate frequencies recombined destructively to generate time holes. Lukens’ team then used a second round of phase modulation to compress the energy further, expanding the duration of the time windows to 36 picoseconds (or 36 trillionths of a second).

the separate frequencies recombined destructively to generate time holes.