Nano-Antenna Technology Improves Infrared Sensors

Researchers working to improve infrared sensors say their gold nano-antenna technology is prepared to move from the lab to market development.

The team asserts that the novel detectors reduce dark current by as much as two orders of magnitude while increasing sensitivity by a factor of three.

The tiny antennas concentrate light onto a much thinner sensor layer than is usually found in infrared sensors, which leads to improved performance. It should lead to cameras and sensors that can deliver much clearer thermal images if successfully translated into commercial use, with potential uses ranging from deep-sky astronomy to security.

Modern, advanced thermal imagers are built around detectors with sensor layers that are 5–10 m deep. Incoming heat is absorbed by the detector material, transforming it into an electrical indication that can be gathered and converted into an image. The thickness of the detector layer affects how much heat can be absorbed and detected by the camera, but larger layers also result in noisier images.

Light is focused on a thinner layer of detector material without affecting the electrical signal by adding sub-wavelength-scale gold nano-antennas in a patterned array of squares or cross shapes.

Current technology can only see about 25% of infrared radiation. Still, the nano-antenna-enhanced design allows detectors to see more than 50% of an object’s infrared radiation while decreasing image distortion from the dark current.

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