Graphene Sensor Shows Mid-IR Potential

A team of researchers created a graphene-based device that could lead to tiny new uncooled detectors operating in the mid-infrared spectrum. Current commercial mid-infrared sensors, which operate in the useful “fingerprint” region full of molecular-specific spectroscopic information, necessitate expensive photodetector materials and bulky instrumentation.
The sensor operates at 12.2 m in the mid-IR spectrum and comprises arrays of plasmonic resonators. The devices, which are only 5 m by 5 m in size, have demonstrated good low-noise performance at room temperature without any cooling.
It is made of large-scale graphene and has a simple two-terminal geometry, and it is an important step toward realizing an on-chip graphene mid-infrared detector array.
The researchers claim they improved sensitivity by taking advantage of the resonant coupling between mid-infrared light and graphene plasmons. The sensors were created on a graphene wafer, with the disk-shaped plasmonic resonators connected by “quasi-one-dimensional graphene nanoribbons.”
They also observed the excitation and absorption of infrared plasmons on the surface of the graphene resonators and nanoribbons at room temperature when they shone a mid-infrared light source onto the setup.
They also discovered that thanks to the graphene nanostructures, the conversion of light into an electrical response was strongly related to the level of plasmonic absorption, with response times allowing detection at gigahertz speeds.

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