One-Way Waveguides Using Gyrotropic Photonic Crystals

Technology #13523

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FIGS. 1A-1B is a TM photonic band structure for a square lattice of YIG rods in air with zero static magnetic field and 1600 Gauss +z static magnetic field;FIGS. 2A-2B are schematic diagrams illustrating cross sectional and planar quasi-two-dimensional views of the inventive gyrotropic photonic crystal structure used in accordance with the invention;FIGS. 3A-3B are electric-field plots illustrating electromagnetic field transmission along the inventive one-way waveguide being unaffected by the shape of the waveguide;FIGS. 4A-4B are graphs illustrating the transmission coefficients between the two antennae used in accordance with the invention; andFIGS. 5A-5F are graphs illustrating the transmission at different values of l, where l is the length of a conducting scatterer between antennae A and B.
Professor John Joannopoulos
Department of Physics, MIT
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Professor Marin Soljacic
Department of Physics, MIT
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Zheng Wang
Department of Physics, MIT
Yidong Chong
Department of Physics, MIT
Managed By
Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

One-way waveguides using gyrotropic photonic crystals

US Patent 7,689,068
Reflection-Free One-Way Edge Modes in a Gyromagnetic Photonic Crystal


This invention is useful for microwave, integrated optical and photonic circuits, and other optical applications.

Problem Addressed

Photonic crystals are structures with periodicity comparable to the wavelength of light. They possess many technologically important optical properties and can suppress back scattering in optical waveguides.


The invention is a waveguide that includes a photonic crystal structure that restricts light to travel in only one direction. This photonic structure comprises of gyromagnetic materials arranged in a two-dimensional lattice formation that exhibits a plurality of one-way edge modes produced as a result of magneto-optic effects. A confining barrier is positioned around the photonic crystal to allow the one-way edge modes to propagate it. Radiation sources placed in or around the photonic crystal structure couples electromagnetic energy in to and out of the waveguide. Finally, attached magnets produce a static external magnetic field that induces the magneto-optic effects such that the one-way modes are allowed to propagate in one direction in the photonic crystal structure.


  • It eliminates backscattering, even in the presence of large disorders
  • It can be implemented to operate in a variety of frequency ranges