What's the new use of graphene in lasers?

Graphene is always surprising and shows even more amazing properties, such as extreme tensile strength or unprecedented conductivity. It may now be of great help to ultra-fast laser systems.

In the original experiment, graphene was made by stripping away thinner graphite layers. Graphite is black, so graphene is also black. In scientific terms, it shows strong light absorption characteristics on a wide bandwidth such as visible light and infrared spectroscopy.

A group of scientists from the Rosendov Research Center in Dresden, Helmholtz, Germany(HZDR) carefully studied the IR absorption characteristics of graphene. In a joint study with research teams from Berlin, Gothenburg and Atlanta, they found new absorption properties of graphene.

So far, we know that graphene can fade under a certain laser energy density. It can be used together with other materials to form a reversible effect of passive absorbers in ultra-fast laser systems. This process can achieve powerful ultrashort pulses in the laser cavity. Therefore, it is of great value to generate the subpicosecond laser pulse.

The researchers found that when a strong infrared pulse with a wavelength of 30 to 40 femtoseconds hits graphene, two fading phenomena occur: the first is 7 microjoules per square centimeter, and the other is 10 microjoules per square centimeter. The first result was surprisingly low and consistent with the new theoretical predictions. They assume that this effect is based on multi-particle scattering involving electrons. This situation is unprecedented and different from the pattern of the second fading phenomenon.

The fading at low energy density depends on the electron mobility, so the speed is very fast. This can support high cyclic rates, which is what is required for high-average power Femtosecond laser systems. In view of the extensive absorption spectral properties of graphene, it can be used in almost the entire visible spectrum and IR spectrum.

HZDR expert Jacob Konig-Otto said: "Graphene is a very promising absorption material and its performance is very stable, very suitable for a wide range of wavelengths. Our findings help to understand the underlying processes and help build better absorbers. "

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