A broadband modulator developed at UCLA's School of Engineering and Applied Science could lead to more advanced medical and security imaging systems.
The modulator is based on an artificial metasurface. Developed by a team led by Professor Mona Jarrahi, the metasurface comprises an array of MEMS units that can be opened and closed by applying a voltage. This action encodes an incoming terahertz wave into a corresponding series of zeroes or ones, which can then transformed into images.
"Our metasurface broadens the realm of metamaterials to broadband operation for the first time and diminishes many of the fundamental physical constraints in routing and manipulating terahertz waves, especially in terahertz imaging and spectroscopy systems," Prof Jarrahi said. "Our device geometry can switch from an array of microscale metallic islands to an array of interconnected metallic loops, altering its electromagnetic properties from a transparent surface to a reflecting surface, which manipulates the intensity of terahertz waves passing through over a broad range of frequencies."
The terahertz band is seen to be attractive for medical imaging and chemical sensing, but current metamaterial based modulators have only have a narrow band of operation. The UCLA device is said to perform across a wide range of the terahertz band with high efficiency and signal clarity.
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