Nanoantennas help detectors see more heat, less noise

phys.org | 11/14/2016 | Staff
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Sandia National Laboratories researchers have developed tiny, gold antennas to help cameras and sensors that "see" heat deliver clearer pictures of thermal infrared radiation for everything from stars and galaxies to people, buildings and items requiring security.

In a Laboratory Directed Research and Development project, a team of researchers developed a nanoantenna-enabled detector that can boost the signal of a thermal infrared camera by up to three times and improve image quality by reducing dark current, a major component of image noise, by 10 to 100 times.

Thermal - Cameras - Sensors - Years - Design

Thermal infrared cameras and sensors have existed for 50 years, but the traditional design of the detector that sits behind the camera lens or a sensor's optical system seems to be reaching its performance limits, said David Peters, a Sandia manager and nanoantenna project lead.

He said improved sensitivity in infrared detectors, beyond what the typical design can deliver, is important for both Sandia's national security work and for other uses, such as astronomical research.

Sensitivity - Image - Quality - Detector - Layer

The sensitivity and image quality of an infrared detector usually depends on a thick layer of detector material that absorbs incoming heat and turns it into an electrical signal that can be collected and turned into an image. The thickness of the detector layer determines how much heat can be absorbed and read by the camera, but thick layers also have drawbacks.

"The detector material is always spontaneously creating electrons that are collected and add noise to the image, which reduces image quality," Peters said. "This phenomenon, called dark current, increases along with the thickness of the detector material—the thicker the material is, the more noise in the image it creates."

Research - Team - Detector - Design - Layers

The research team developed a new detector design that breaks away from relying on thick layers and instead uses a subwavelength nanoantenna, a patterned array of gold square or cross shapes, to concentrate...
(Excerpt) Read more at: phys.org
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