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Photonic Bandgap Structures

Photonic Bandgap Structures. By Akshay V. Hegde Graduate Student Dept. of Electrical Engineering Course: Optical Communications Instructor: Dr. Pao-Lo Liu. Agenda. Photonic Band Gaps Photonic Band Gaps & Bragg’s Law Natural PBS Artificial PBS Fabrication of PBS Self-Assembly Process

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Photonic Bandgap Structures

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  1. Photonic Bandgap Structures By Akshay V. Hegde Graduate StudentDept. of Electrical Engineering Course: Optical Communications Instructor: Dr. Pao-Lo Liu

  2. Agenda • Photonic Band Gaps • Photonic Band Gaps & Bragg’s Law • Natural PBS • Artificial PBS • Fabrication of PBS • Self-Assembly Process • Photonic Crystal Fiber • Future Applications • Photonic Giants

  3. Photonic Band Gaps • Photons with a certain range of wavelengths do not have an energy state to occupy in a structure • These photons are forbidden in the structure and cannot propagate • Analogous to forbidden energy gaps in semiconductors E = (hc)/λ

  4. Photonic Band Gaps & Bragg’s Law • Periodic objects reflect incident waves when the dimensions, wavelength and interplanar spacing, satisfy Bragg's Law • Bragg’s Law is valid for any EM wave in any periodic object

  5. Natural PBS The Gemstone Opal

  6. Natural PBS The Mitoura Grynea

  7. A lattice fabricated from layers of silicon "matchsticks" Spherical air holes in a material with a high refractive index Artificial PBS

  8. Fabrication of PBS • Two popular methods • Lithography • Defects can be precisely controlled • Ideal for small scale production • Expensive and complex • Self-Assembly • Defects cannot be controlledprecisely • Works well for bulk production • Inexpensive and simple An Opal Template

  9. Self-Assembly Process

  10. Photonic Crystal Fiber • A long thread of silica glass with a periodic air holes running down its length

  11. Type 1- The central hole is absent, high-index defect acts as core • Type 2 - The core has an extra hole, which is a low-index defect (Photonic band gap fiber) • Light is guided along the low refractive index air core by photonic band gap confinement effect • Presently, fabrication of 3D photonic crystals on the scale of a micron is difficult

  12. High-Index Defect Fiber Low-Index Defect Fiber

  13. Future Applications • Highly efficient photonic crystal lasers • High resolution spectral filters • Photonic crystal diodes and transistors • High efficiency light bulbs • Optical computers • Telecommunication & computer networks • Photonic clothes and candy bars?

  14. Photonic Giants • NEC Research Institute & Electrical Engineering Dept. at Princeton University • Dept. of Electrical Engineering at UCLA • Massachusetts Institute of Technology • Sandia National Laboratories, California • Rockwell International, California • Bell Labs • Corning

  15. References • Articles on “Photonic Band Gap Links” (http://pbglink.com) • Physics Web (http://physicsweb.org/article/world/13/8/9) • Optoelectronics Group, University of Bath (http://www.bath.ac.uk/physics/groups/opto/pcf.html) • Wired Magazine (http://www.wired.com/wired/archive/8.09/optical.html)

  16. Thank You!

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