Angular Photonic Band Gap

Technology #14368

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A microscope image of the tungsten photonic crystal structure reveals the precise uniform spacing of cavities formed in the material, which are tuned to specific wavelengths of light.  Image courtesy of Y.X. Yeng, et al.
Professor Marin Soljacic
Department of Physics, MIT
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Ivan Celanovic
Institute for Soldier Nanotechnologies, MIT
Rafif Hamam
Department of Physics, MIT
Professor John Joannopoulos
Institute for Soldier Nanotechnologies, MIT
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Peter Bermel
Research Laboratory of Electronics, MIT
Michael Ghebrebrhan
Research Laboratory of Electronics, MIT
Adrian Yang
Department of Electrical Engineering & Computer Science, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Discriminating electromagnetic radiation based on angle of incidence

US Patent US 9,057,830
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Angular photonic band gaps transmit or absorb electromagentic radiation based on the polarization and reflecting electromagnetic radiation of certain frequencies. Applications for this effect are found in solar energy, as this technology enables a nearly perfect greenhouse effect. Also, this invention will be useful for structures designed to "trap" light of a known incidence angle.

Problem Addressed

An issue with current technology is the low efficiency of the solar-energy conversion, which is limited by re-radiation of sunlight, consequently causing energy loss. This invention demonstrates how light close to normal incidence can be near perfectly transmitted, independent of polarization. Moreover, this invention uses photonic crystals whose constituents have an anisotropic dielectric and/or magnetic response to enable such transmission.


This invention presents a novel class of material systems that strongly discriminate light based on the angle of incidence, over a broad range of frequencies, and irrespective of the polarization. The meta-material system proposed consists of a one-dimensional periodic photonic crystal whose constituents possess anisotropic properties. This photonic material comprising of a plurality of photonic crystals can be used to selectively transmit and/or selectively absorb one portion of incoming electromagnetic radiation while reflecting another portion of incoming electromagnetic radiation. The design structure opens an angular gap for both polarizations over a certain frequency range with the possibility of enlarging the frequency range to the specific angular discrimination desired. 


  • Reduces energy loss
  • Wider range of light that can be identified