Researchers Cultivate New Device to Measure Polarization of Light

Researchers Cultivate New Device to Measure Polarization of Light
Close up view of the semitransparent polarization detector. The square area that shows up well is one of the gold electrodes, underneath which is the organic photovoltaic (OPV) material which converts polarized light into an electrical signal. In these images, the background light is linearly polarized. Rotating the detector within this polarized light reduces the transmitted light's brightness as the device is aligned to it. (a) OPV device at 0 degrees; (b) 45 degrees; and (c) 90 degrees. At 90 degrees, the device absorbs the most light, indicating that the background polarization state is oriented parallel to the OPV. This change would be represented as an increase in the detected current. Credit: Michael Kudenov, NC State University

Scientists from North Carolina State University have cultivated a novel tool to detect and measure the polarization of the light. Instead of multiple samples needed for previous technologies, it depends on a single spatial sampling of the light. This new device uses unique properties of basic polymers, for polarization identification and measurement.

Light is made up of an electric field. Light polarization is when electric field ripples and the direction through which field ripples. The polarization of light can be affected in certain ways when light bounces off or is scattered by physical objects.

If the field ripples inconstantly then it is known as the polarization of light.

Michael Kudenov, an assistant professor of electrical and computer engineering at NC State and lead investigator said, “Because polarization has different applications, we want to identify and measure polarization. For example, polarization detectors can be used to choose man-made materials against natural surfaces. This surfaces can be used in protection and security systems. They could also be used for atmospheric monitoring, measuring polarization to track the size and distribution of particles in the atmosphere, which is useful for both air quality and atmospheric research applications.”

This new device includes three polarization detectors. These three detectors are made up of the basic polymer conductors. Each detector is responsive to a certain orientation of the polarization. When light enters into the device, the first detector measures one adjustment of the polarization, and the remainder of the light passes through. This process is repeated with remaining detectors. It is done by effectively permitting each detector to take a partial polarization measurement of the same beam of light. The measurements of all three detectors transferred to the model which calculates the complete polarization of the light.

Kudenov says, “Most types of polarized light, particularly in natural environments, have a large linear polarization signature. And three measurements are sufficient for us to calculate the state of linear polarization in a light sample.”

Previous technologies were depended upon multiple light samples. The samples were taken at different times or at the same time but from different points in space, which can influence the accuracy of results.

By using a laser to provide initial proof-of-concept data, researchers have tested this new device. Previous tests show that the device can check errors as low as 1.2 percent.

Kudenov says, “It’s a good starting point, though not as good as the best polarization detectors currently on the market. However, we’re optimistic that we’ll be able to reduce the measurement error significantly as we improve the device’s design. We’re really just getting started.”


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