Optical Yagi-Uda Nanoantennas
April 25, 2012
Light is an electromagnetic wave, just like radio, so it should be possible to scale radio antenna designs to function for light. The critical dimensions in antennas need to be about the same as the wavelength of the electromagnetic radiation. That's why AM radio towers, which transmit frequencies of about a megahertz, are more than a hundred meters high; and the Wi-Fi antenna on your wireless router (2.45 GHz) is just a few inches long.
Since visible light has a wavelength of about 500 nanometers, optical antennas have only become possible with the advent of routine fabrication of nanoscale structures. I wrote about optical antennas in the context of solar energy conversion in a previous article (Optical Antennas, June 13, 2011).
The Yagi-Uda antenna has been a popular antenna type for more than eighty years. Its main advantage is that it's directional and offers gain over the isotropic; that is, it concentrates its electromagnetic energy in one direction for a transmitter. For a receiver, it enhances sensitivity in one direction, while at the same time rejecting noise away from that direction. This antenna concept was published in Japanese by Shintaro Uda and
Hidetsugu Yagi, but it was called a Yagi antenna in the West, since Yagi published descriptions in English.
As shown in the photograph, above, the construction of such antennas is very simple. The principle of operation is related to the concept of phase interference. The reflector element (see schematic) is spaced a quarter of a wavelength from the driven element, which leads to constructive interference for waves in the plane of the elements and a lesser signal at other angles. The director elements likewise re-radiate energy they receive in a way that enhances the signal of the driven element in the forward direction and diminishes the radiation in other directions.
Yagi patented the concept in 1932, although his patent may seem strange to radio engineers of today. Yagi showed his directional antenna concept in an array of vertical elements on the ground. This Yagi architecture might be worthwhile resurrecting in an optical analog.
A team of scientists from the Nonlinear Physics Centre and the Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS) of the Research School of Physics and Engineering, the Australian National University (Canberra, Australia) has just published a preprint of a very thorough review article of the current and potential uses of optical Yagi-Uda antennas. A representative optical nanoantenna is shown in the following figure.
The Australian authors discuss and compare the physics behind electromagnetic wave propagation for radio and optical wavelengths; and they analyze the limits for application of this antenna type in the optical domain. Their paper describes some novel broadband and wavelength tunable Yagi-Uda optical nanoantennas, including arrays of such antennas. Most interesting from a practical viewpoint are the several methods of exciting the active element of such nanoantennas.
One application I found most interesting was the use of paired optical Yagi-Uda antennas to transmit an optical signal across a chip without the need for an optical waveguide, as shown in the figure. In a multichip module, this may even be a means of communicating between chips.
My first experience with Yagi-Uda antennas was as a high school senior. I built a radio telescope as a science fair project. Shown below is the Yagi-Uda antenna I built from copper pipes. This photograph was taken on the roof of my high school, which is now a housing complex for senior citizens. Perhaps I can get a room there, some day, in the same location as my high school homeroom. That's what they call full circle.
|Schematic diagram of a Yagi-Uda antenna.|
(Illustration by author, rendered using Inkscape).
| ||My senior high school science fair project included this Yagi-Uda antenna I built from copper piping for a radio telescope.|
This photograph shows its placement on the school roof (43.100903° latitude, -75.232664° longitude).
(click for larger image).
- Hidetsugu Yagi, "Variable Directional Electric Wave Generating Device," US Patent No. 1,860,123, May 24, 1932.
- Ivan S. Maksymov, Isabelle Staude, Andrey E. Miroshnichenko and Yuri S. Kivshar, "Optical Yagi-Uda nanoantennas," arXiv Preprint Server, April 2, 2012.
- J.D. Kraus, "Antennas," McGraw-Hill (New York, 1988).
Permanent Link to this article
Linked Keywords: Light; electromagnetic wave; radio; radio antenna; wavelength; AM radio tower; frequency; megahertz; meter; IEEE 802.11; Wi-Fi; wireless router; GHz; inch; visible light; nanometer; nanoscale; solar energy; Yagi-Uda antenna; gain over the isotropic; energy; transmitter; receiver; noise; Japanese language; Shintaro Uda; Hidetsugu Yagi; Western world; West; English language; science fair; Winegard HD6065P High Definition FM Antenna; FM Radio Detection of Meteors Web Site; phase interference; reflector element; constructive interference; plane; Inkscape; patent; radio engineer; scientist; Nonlinear Physics Centre; Centre for Ultrahigh Bandwidth Devices for Optical Systems (CUDOS); Research School of Physics and Engineering; Australian National University; Canberra, Australia; preprint; arXiv Preprint Server; Australia; physics; wideband; broadband; integrated circuit; chip; optical waveguide; multichip module; high school; senior; radio telescope; copper; pipe; Kodak Photographic Film; senior citizen; homeroom; full circle.
Latest Books by Dev Gualtieri
Thanks to Cory Doctorow of BoingBoing for his favorable review of Secret Codes!
Blog Article Directory on a Single Page
- Levitation - March 27, 2017
- Soybean Graphene - March 23, 2017
- Income Inequality and Geometrical Frustration - March 20, 2017
- Wireless Power - March 16, 2017
- Trilobite Sex - March 13, 2017
- Freezing, Outside-In - March 9, 2017
- Ammonia Synthesis - March 6, 2017
- High Altitude Radiation - March 2, 2017
- C.N. Yang - February 27, 2017
- VOC Detection with Nanocrystals - February 23, 2017
- Molecular Fountains - February 20, 2017
- Jet Lag - February 16, 2017
- Highly Flexible Conductors - February 13, 2017
- Graphene Friction - February 9, 2017
- Dynamic Range - February 6, 2017
- Robert Boyle's To-Do List for Science - February 2, 2017
- Nanowire Ink - January 30, 2017
- Random Triangles - January 26, 2017
- Torricelli's law - January 23, 2017
- Magnetic Memory - January 19, 2017
- Graphene Putty - January 16, 2017
- Seahorse Genome - January 12, 2017
- Infinite c - January 9, 2017
- 150 Years of Transatlantic Telegraphy - January 5, 2017
- Cold Work on the Nanoscale - January 2, 2017
- Holidays 2016 - December 22, 2016
- Ballistics - December 19, 2016
- Salted Frogs - December 15, 2016
- Negative Thermal Expansion - December 12, 2016
- Verbal Cues and Stereotypes - December 8, 2016
- Capacitance Sensing - December 5, 2016
- Gallium Nitride Tribology - December 1, 2016
- Lunar Origin - November 27, 2016
- Pumpkin Propagation - November 24, 2016
- Math Anxiety - November 21, 2016
- Borophene - November 17, 2016
- Forced Innovation - November 14, 2016
- Combating Glare - November 10, 2016
- Solar Tilt and Planet Nine - November 7, 2016
- The Proton Size Problem - November 3, 2016
- Coffee Acoustics and Espresso Foam - October 31, 2016
- SnIP - An Inorganic Double Helix - October 27, 2016
- Seymour Papert (1928-2016) - October 24, 2016
- Mapping the Milky Way - October 20, 2016
- Electromagnetic Shielding - October 17, 2016
- The Lunacy of the Cows - October 13, 2016
- Random Coprimes and Pi - October 10, 2016
- James Cronin (1931-2016) - October 6, 2016
- The Ubiquitous Helix - October 3, 2016
- The Five-Second Rule - September 29, 2016
- Resistor Networks - September 26, 2016
- Brown Dwarfs - September 22, 2016
- Intrusion Rheology - September 19, 2016
- Falsifiability - September 15, 2016
- Fifth Force - September 12, 2016
- Renal Crystal Growth - September 8, 2016
- The Normality of Pi - September 5, 2016
- Metering Electrical Power - September 1, 2016
Deep Archive 2006-2008