Wonder substance pulses QUADRILLION lasers per second
Is there anything graphene can't do?
Light covers a very wide spectrum, making its potential communications capacity nearly infinite, so why does the world stick to a few wavelengths for communications? The reason is that currently available amplifier components only work in the 1330 and 1550 nm wavelengths.
However, adding yet another string to its already-impressive bow, graphene has been found to be a cheap way to produce femtosecond laser pulses across a wide range of wavelengths, with researchers saying the material could ultimately be used to create laser pulses across the entire spectrum of visible light.
Nature reports that graphene's broad wavelength potential comes from a peculiar property: it lacks the “band gap” that exists in most non-metallic solids.
In materials with a band gap, electrons either have a low energy state in which they're bound to atoms, or a high energy state, where the electrons are able to move about and carry an electrical current. To cross the band gap, the electron has to absorb a specific amount of energy. If that energy is coming from light, that means it has to be at a specific wavelength, associating particular materials with particular wavelengths.
That, for example, is why the cheap erbium-doped optical amplifier is associated with 1550nm, at which it produces gain.
With no band gap, graphene can contain electrons across a continuum – meaning it can absorb light across a continuum. It's this property that has researchers expecting it can be the basis of lasers working across a much wider range of wavelengths, at much lower cost than current technologies.
It doesn't represent the entire ecosystem that would be needed to break optical communications out of their current wavelength straitjacket, but it would be an important advance.
Nature notes that the graphene femtosecond pulse lasers would also be useful in micromachinery and medicine. ®
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