Surface-Plasmon Index Guided Waveguides

Technology #10850

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FIG. 1 illustrates ω-k diagrams (solid curves) for conventional layered Surface Plasmon structures (insets A–D) with ωhi=4 and ωlow=1 (air).FIGS. 2 a–b depict ω-k diagrams (grey curves calculated via the effective-index method) for SPIG waveguide structures (in-sets) with ω/λp,=0.25 and d/λp, =0.02.FIGS. 3 a–b depict ω-β diagrams for SPEIG waveguide structures (insets) with ω/λp=0.25 and d/λp=0.02.
Professor John Joannopoulos
The Institute for Soldier Nanotechnologies, MIT
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Professor Yoel Fink
Research Laboratory of Electronics, MIT
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Professor Marin Soljacic
Research Laboratory of Electronics, MIT
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Kerwyn Huang
Research Laboratory of Electronics, MIT
Mihai Ibanescu
Research Laboratory of Electronics, MIT
David Chan
Research Laboratory of Electronics, MIT
Aristeidis Karalis
Research Laboratory of Electronics, MIT
Elefterios Lidorikis
Research Laboratory of Electronics, MIT
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Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Surface-plasmon index guided (SPIG) waveguides and surface-plasmon effective index guided (SPEIG) waveguides

US Patent 7,184,641
Surface-Plasmon-Assisted Guiding of Broadband Slow and Subwavelength Light in Air


This invention can be used in nanophotonics, ultrafast optics, optical memories, and quantum computing 

Problem Addressed

Conventional methods of guiding light are limited because they have a fairly small frequency bandwidth and high propagation losses. There is a need for a more efficient waveguide that can be used over a wide range of frequency regimes.


This invention presents a new class of surface plasmon waveguides. The basis of these structures is the presence of surface plasmon modes, supported on the interfaces between the dielectric regions and the flat unpatterned surface of a bulk metallic substrate. The SP waveguides can simultaneously shrink length, time and energy scales, allowing for easy coupling over their entire bandwidth of operation. This attribute enables the design of nanoscale SP-enabled optical micro-cavities. 


  • It can be used for many frequency regimes (from GHz and lower, to optical)
  • It can operate with minimal absorption losses, limited only by the intrinsic loss of the metallic substrate