Metasurface holograms: Fast, compact polarization measurements for spectroscopy and sensing

phys.org | 4/4/2017 | Staff
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For the first time, researchers have used ultra-thin layers of 2-D structures known as metasurfaces to create holograms that can measure the polarization of light. The new metasurface holograms could be used to create very fast and compact devices for polarization measurements, which are used in spectroscopy, sensing and communications applications.

Metasurfaces are optical elements with nanoscale features and an overall thickness that is less than 1/50th that of a human hair. They can be made with standard microelectronics fabrication techniques, enabling mass production, and can be easily integrated into wafer-scale optical systems. Despite these promising features, they are not yet used in many practical applications.

Optica - Optical - Society - Journal - Impact

In Optica, the Optical Society's journal for high impact research, a multi-institutional group of researchers report using metasurface holograms to effectively and quickly determine polarization at near-infrared to visible wavelengths. The new work represents a step toward functional metasurface-based devices to support a range of applications from telecommunications to chemical analysis.

"Holograms made from metasurfaces are an efficient and effective way to generate high-quality images with subwavelength resolution," said research team leader Xueqian Zhang from Tianjin University, China. "Our work uniquely applies metasurface holograms to polarization measurements, which could enable camera-size devices that measure polarization in one step without moving parts."

Household - Light - Sources - Light - Directions

Although sunlight and most household light sources emit unpolarized light that oscillates in all directions, optical components such as filters can be used to produce polarized light that propagates in just a single plane—typically vertical or horizontal. Analytical instruments such as spectrometers can measure how light polarization changes after interacting with a material to determine its physical properties. Different light polarizations can also be used to send multiple signals through optical fibers for telecommunications applications.

Conventional methods for determining polarization often require multiple measurements, bulky optical setups or precise adjustment of high-quality optical components to indirectly determine the...
(Excerpt) Read more at: phys.org
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