1. Photonic Bandgap Structures By Akshay V. Hegde Graduate Student Dept. 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. Artificial PBS  A lattice fabricated from layers of silicon "matchsticks"  Spherical air holes in a material with a high refractive index

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 controlled precisely  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 FiberLow-Index Defect Fiber High-Index Defect FiberLow-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) http://pbglink.com  Physics Web (http://physicsweb.org/article/world/13/8/9) http://physicsweb.org/article/world/13/8/9  Optoelectronics Group, University of Bath (http://www.bath.ac.uk/physics/groups/opto/pcf.h tml) http://www.bath.ac.uk/physics/groups/opto/pcf.h tmlhttp://www.bath.ac.uk/physics/groups/opto/pcf.h tml  Wired Magazine (http://www.wired.com/wired/archive/8.09/optical.html) http://www.wired.com/wired/archive/8.09/optical.htmlhttp://www.wired.com/wired/archive/8.09/optical.html

16. Thank You!