"Time Telescope" Could Boost Fibre-Optic Communications

An anonymous reader writes "A time lens can focus a chunk of time to a point, rather like a normal lens focuses light rays. Put two time lenses together and you can create what a Cornell University team calls a 'time domain telescope' which can magnify time. They sent a 2.5 nanosecond long light pulse, encoding 24 bits of information, into their time telescope. What came out on the other side was the same 24 bit pulse, but compressed into 92 picoseconds. Squashing more information into a light pulse could help to send more information via optical fibres."

Comments

Re:First descibed in 1834 by John Scott Russell

[kmac06]

This is not at all an oversell (though admittedly bad journalism). It's not the same as chirped pulse amplification or prism compression.

In this case, you start out with an essentially monochromatic long pulse, whose intensity is modulated very slowly compared to the frequency of the light, but as fast as possible using typical telecom electrical modulators. A monochromatic pulse cannot be compressed using a grating or prism. Then the wavelength of the pulse is shifted, with the amount shifted depending on the relative position in the pulse (this is the "time-domain lens"). What you have now is similar to a chirped pulse, which is compressed using a long fiber (I don't know why they don't use prism compression or something else faster here). The time-domain lensing is then undone, "de-chirping" the pulse, leaving you with a much shorter essentially monochromatic pulse at the starting wavelength, with the same amplitude modulation (i.e., carrying the same information).

The point being a huge increase in the amount of information that can be carried in a fiber.