Next Generation of Optical Antennas

Antennas catch radio waves from the air and convert the energy into electrical signals that feed modern tele­communications. They can also convert electrical signals into radio waves. Optical engineers and scientists like Anthony J. Hoffman, associate professor in the Department of Electrical Engineering at the Univer­sity of Notre Dame, are working toward leveraging these devices to control light instead of radio waves. Hoffman has been focusing his efforts on next-generation materials, tech­nologies and devices for infrared light.

Epsilon-near-zero (ENZ) materials offer unique phenomena, including wavefront engineering, enhanced light funneling through subwavelength apertures, order-of-magnitude extension of the local wavelength in waveguiding structures, and spectrally-selective absorption and thermal emissions. (Source: U. Notre Dame)

Most often associated with night vision, infrared light has many uses in optical sensing and detection. Optical antennas enable engineers to control how light interacts with materials and can localize light to subwave­length dimensions for use with many of today’s nanoscale devices. Now, a special class of optical materials can drasti­cally alter the properties of optical antennas. This control of properties opens the door for new ways to engineer optical antennas.

Hoffman and his colleagues worked largely in two campus facilities – the Notre Dame Nano­fabrication Facility and the Notre Dame Integrated Imaging Facility – to design, fabricate and demonstrate optical antennas using an epsilon-near-zero (ENZ) material. ENZ materials offer unique phenomena, including wavefront engi­neering, enhanced light funneling through subwave­length apertures, order-of-magnitude extension of the local wavelength in wave­guiding structures, and spectrally-selective absorption and thermal emissions.

Building optical antennas on an ENZ material allowed the team to design and demonstrate a multimode, nearly mono­chromatic antenna, a new class of optical antennas, that could have use in sensing, imaging, infrared opto­electronics and thermal emission control appli­cations. It also offers the potential of new types of optical devices.

Hoffman, an affiliated member of the Center for Nano Science and Tech­nology, and his team are currently working to incor­porate their optical antennas into semi­conductor devices in order to improve the inter­action between light and semiconductor materials, thus creating the next generation of infrared sources. (Source: U. Notre Dame)

Reference: O. Dominguez et al.: Monochromatic Multimode Antennas on Epsilon‐Near‐Zero Materials, Adv. Opt. Mat., online 7 March 2019; DOI: 10.1002/adom.201800826

Link: Integrated Imaging Facility, University of Notre Dame, Notre Dame, USA

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