Efficient one-way optical nanoantenna is also a beam scanner

March 7, 2013
Fed by an optical waveguide, an optical nanoantenna can be used to emit infrared (IR) or visible light in a highly directional manner (just as a radio antenna does for radio waves).

Fed by an optical waveguide, an optical nanoantenna can be used to emit infrared (IR) or visible light in a highly directional manner (just as a radio antenna does for radio waves). However, backreflections originating at the juncture between waveguide and optical antenna sap the efficiency of the configuration. Because scaling the matching-circuit idea for radio antennas down to optical wavelengths is not practical, another approach must be used. Yakir Hada and Ben Steinberg of Tel Aviv University (Tel Aviv, Israel) have come up with a potential solution: a waveguide that ends in a structure that permits only one-way propagation.

The nonreciprocal light transmission happens as a result of the interaction of nonreciprocal optical Faraday (cyclotron) rotation and structural chirality. Faraday radiation occurs when charged particles move in a magnetic field, and so the one-way waveguide contains plasmonic structures (called a subdiffraction chain, or SDC) to which an external magnetic field is applied. For chirality, the researchers design the SDC in a spiral shape (actually a chain of metal ellipsoids spaced 11 nm apart and unidirectionally rotated along the chain). The researchers modeled the structure, showing that a chain length of about three wavelengths produced a directional beam at high efficiency (81% for the antenna itself) for a 0.4 μm wavelength. In addition, changing the strength of the applied magnetic field changed the beam direction, producing a scanner with a 60° deflection range. Contact Steinberg at [email protected].

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

March 31, 2025
Enhance your remote sensing capabilities with Chroma's precision-engineered optical filters, designed for applications such as environmental monitoring, geospatial mapping, and...
March 31, 2025
Designed for compatibility with a wide range of systems, Chroma's UV filters are engineered to feature high transmission, superior out-of-band blocking, steep edge transitions...
March 31, 2025
Discover strategies to balance component performance and system design, reducing development time and costs while maximizing efficiency.
March 31, 2025
Explore the essential role of optical filters in enhancing Raman spectroscopy measurements including the various filter types and their applications in improving signal-to-noise...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!