Abstract
All-optical switches have been considered as a promising solution to overcome the fundamental speed limit of the current electronic switches. However, the lack of a suitable third-order nonlinear material greatly hinders the development of this technology. Here we report the observation of ultrahigh third-order nonlinearity about 0.45 cm2/GW in graphene oxide thin films at the telecommunication wavelength region, which is four orders of magnitude higher than that of single crystalline silicon. Besides, graphene oxide is water soluble and thus easy to process due to the existence of oxygen containing groups. These unique properties can potentially significantly advance the performance of all-optical switches.
Highlights
Silicon nitride[7, 8]
The vacuum filtration process involves the filtration of a Graphene oxide (GO) suspension through an anodic aluminium oxide (AAO) or polyethylene terephthalate (PET) membrane
One should note that βeff is an equivalent coefficient which combines the effects of saturable absorption (SA) and other nonlinear absorptions
Summary
Silicon nitride[7, 8] These materials have amazingly large FOM values, they suffer from small Kerr coefficient and result in power-hungry devices. Graphene shows a remarkable Kerr coefficient of ~102 cm2/GW at 1550 nm[10], but it is accompanied by highly nonlinear absorption due to the zero bandgap. Bi2Se3 shows a nonlinear refractive index of 10 −1 cm2/GW at 800 nm[15], but it is highly absorptive at telecommunication wavelength as its bandgap is ~0.3 eV. The observed n2 is four orders of magnitude larger than single crystal silicon with negligible high order absorption, which makes GO a promising candidate for all-optical switches in the telecommunication regime
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