Directional Control of Light
Creating a nanoscale-material that can achieve light selection based purely on the angle of propagation is a long-standing scientific challenge. We tailored the overlap of the band gaps of multiple one-dimensional photonic crystals, each with a different periodicity, in such a way as to preserve the characteristic Brewster modes across a broadband spectrum. Our method enables transparency throughout the visible spectrum at one angle—the generalized Brewster angle—and reflection at every other viewing angle.
Background & Motivation:
The ability to control light has long been a major scientific and technological goal. In electromagnetic theory, a monochromatic electromagnetic plane wave is characterized (apart from its phase and amplitude) by three fundamental properties: its frequency, its polarization, and its propagation direction. The ability to select light according to each of these separate properties would be an essential step in achieving control over light. Tremendous progress has been made toward both frequency selectivity and polarization selectivity. Frequency selectivity can be obtained, for example, by taking advantage of photonic band gaps in photonic crystals. Polarization selectivity is accomplished, for example, by means of a “wire grid” polarizer or by exploiting birefringent materials. Methods based on interference and resonance effects have been explored for angular selectivity, but they have limited applications because they are sensitive to frequency.
In our work, we tailor the overlap of the bandgaps of multiple one-dimensional photonic crystals, each with a different periodicity, in such a way to preserve the characteristic Brewster modes across a broadband spectrum. We prove this idea theoretically and realize it experimentally with an all-visible-spectrum, p-polarized angularly selective material-system. Our method enables transparency throughout the visible spectrum at one angle, the generalized Brewster angle, and reflection at every other viewing angle.
More detailed description can be found in our paper published on Science, March 28th, 2014:
- Y. Shen, D. Ye, I. Celanovic, S. G. Johnson, J. D. Joannopoulos and M. Soljacic, "Optical Broadband Angular Selectivity", Science 343 (6178), 1499-1501 (2014) [pdf]
And an extended work published on Physical Review B, September 15th, 2014:
- Y. Shen, D. Ye, L. Wang, I. Celanovic, L. Ran, J. D. Joannopoulos, and M. Soljacic, " "Metamaterial broadband angular selectivity", Physical Review B Vol.90, p.125422, (2014)
Here is a more detailed invited review paper published on Applied Physics Reviews, March 1st, 2016, which discussed many potential applications and outlook of this technology:
- Y. Shen, C. Hsu, Y. Yeng, J. D. Joannopoulos, and M. Soljacic, " "Broadband Angular Selectivity of Light at the Nanoscale: Progress, Applications and Outlook", Appl. Phys. Rev. 3, 011103 (2016)
This work was chosen to be one of top 100 science stories of 2014 by the Discover Magazine.
This work was featured on MIT homepage on March 28th, 2014.
Some nice news article written about this work:
- A new angle on controlling light, by David L. Chandler (MIT News Office).
- Vanishing mirror turns into a window as you spin it, by Jacob Aron (April 5th, 2014 issue of New Scientist).
- New material offers angular control over light, by Hamish Johnston (Physics World)
Press Coverages also includes:
Discover Magazine, MIT News, MIT Energy Initiative, PhysicsWorld, Physics Today, Photonics.com, Science Daily, Position & Promotions, iScience Times, Science News, eurekalert!, CleanTechnica, Optics & Photonics, Science Newsline, LabOnline, Daily Kos, Electronics 360, Student Science, Knovel, Global Times, Novus Light, EE Times, The Orange Room, The Raw Story, DMWmedia, Prezi.com, XinhuaNet