1. Photonic Crystals Photonics Research Laboratory
Department of Electrical and Computer Engineering
Old Dominion University, Norfolk, VA 23529

2. Research Team Dr. Sacharia Albin Advisor
Dr. Shangping Guo Post Doc Fellow
Feng Wu Ph.D. Candidate
Khalid Ikram Master’s Student

3. Introduction 1887 1987 Periodic structures in 1D, 2D and 3D- D p e r i o d c n t w s 3 h 1
Periodic structures in 1D, 2D and 3D
Period comparable to wavelength (sub-microns)
Possess photonics band gaps (PBGs) which prohibit any light modes
Obey Maxwell’s equations, predicting fields accurately
Similar but fundamentally different from semiconductors
PBG is periodic structures. The graph shows a schematic of photonic crystal, 1D multilayer system, 2D periodic square rods, 3D woodpile structures. The main features of PBG materials are given as follows:

4. No EMAG Radiation Inside PBG

5. Woodpile PBG using Silicon Micro-machining
This is a 3D woodpile photonic crystal fabricated in Sandia National Lab by Shawn Lin. He used the silicon micromachiing technology, which is considered promising
From Sandia National Laboratory

6. Photonic Micropolis Research at MIT
This graph is MIT's photonic micropolis. This gives a image how photonic crystals act important roles in future optical integrated circuits. Light is stored, guided, coupled, bended as design in 1D, 2D and 3D photonic crystals.
Research at MIT

7. Research at ODU Photonics Lab
Planar photonic devices based on 2D photonic crystals Basic geometries: square, triangular, honeycomb, kagome

8. Examples of Photonic Devices/Applications
Optical insulator
Perfect dielectric mirror
Optical filter
Polarizer
Super-lensing
Negative refraction

9. Defects in PBG Point defects and line defects High Q filter
Zero-threshold cavity
Resonance center for controlled energy transfer
Linear waveguiding & bending
Ideal integrated devices

10. PBG Defect Laser
To offer everyone some experience of what photonic crystals can do, some important results obtained by the PBG community are shown here. The first is the smallest defect mode laser by Painter et al in Caltech.
Periodic air holes in high index material forms a 2D photonic crystal. The center air hole is removed and form a resonant cavity. Light is confined in the cavity. Spontaneous emission in the band gap is prohibitted, but for the defect mode is enhanced. This produces a microlaser with very low threshold.
PBG provides: High Q cavity + ASE suppression, leading to micro sized, zero-threshold laser.
From UCLA

11. Example of High Q filter
Resonant cavity: high Q filter ~10,000, resonant frequency, Q and energy pattern can be designed.
S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect modes in photonic crystals”, Opt. Express 11, (2003)

12. Example of High Q filter
Possible high Q filters in a 2D square lattice, useful for many devices: add/drop, waveguiding cross, splitter, filters, etc.
S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect modes in photonic crystals”, Opt. Express 11, (2003)

13. Field Profile – Single Defect
S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect
modes in photonic crystals”, Opt. Express 11, (2003)

14. Example of Linear Waveguide
Linear waveguiding in arbitrary medium
S. Guo, PhD Dissertation, ODU, 2003

15. Linear Waveguide : Pulse Propagation
Peaks in transmission spectrum, due to the cavity resonant effect, or DBR effect (contributes to special dispersion)
Phase relation
S. Guo, PhD Dissertation, ODU, 2003

16. Coupled Cavity Waveguide
S. Guo, PhD Dissertation, ODU, 2003

17. Coupled Cavity Waveguide
5 cavities, 5 peaks in the transmission
Large propagation delay in the cavity (delay line)
A setup time required
Distortion of ultra-narrow pulses
S. Guo, PhD Dissertation, ODU, 2003

18. 100% Transmission at Sharp Bends
S. Guo, PhD Dissertation, ODU, 2003

19. Pulse Propagation Through Sharp Bends
Whole band can pass the bend with transmission over 80%
Peak transmission occurs at some frequencies due to waveguiding and resonant tunneling at the bend
S. Guo, PhD Dissertation, ODU, 2003

20. Add/drop channels using CCWsX
S. Guo, PhD Dissertation, ODU, 2003

21. CCW for add/drop Channels
S. Guo, PhD Dissertation, ODU, 2003

22. Photonic Crystal Fiber
Holey fiber with a micro-structured cladding
Photonic band gap fiber: guiding light in air
Bragg fiber using perfect cylindrical dielectric mirrors (the Omniguide fiber)

23. Holey Fibers
This graph shows an important photonic crystal device, the photonic crystal fiber. Compared to conventional fiber, periodic air holes are drilled in the cladding and the core can be anything. Pic A shows a solid core, B is the guidded mode intensity pattern. C shows a dual core fiber. D is a fiber with high nonlinear effect. E is a fiber with a small air core. The other graphs show a large air core.
Microstructured holey fiber or PCFs, Russel et al, Science, 2003 (Univ. Bath)

24. Spatial Dispersion
S. Guo, PhD Dissertation, ODU, 2003

25. Index-guiding Triangular PCF Endless Single Mode
Single mode from UV to infrared
Short wavelength gets a better confinement
S. Guo, PhD Dissertation, ODU, 2003

26. Air-guiding PCFs

27. Bragg Fiber with Omni-Reflector
Omnidirectional Mirrors

28. Advantages
Light guiding (at any wavelength) in air, e.g. the CO2 laser transport for medical applications
No need for high purity materials
Reduced nonlinear effect, zero polarization mode dispersion, large power transfer
Asymptotic single mode propagation

29. Modeling and Simulation Methods
Photonics lab has developed many methods for the research on photonic crystals
Plane wave method: to calculate the band gap structure of any photonic crystal
Time-domain: for band gap calculation
FDTD: to simulate the field dynamics in arbitrary dielectric materials.
Fiber, PCF, Bragg fiber analysis tools

30. Modeling and Simulation Methods
The PWM and FDTD methods
Solved most problems in PBG field
Our free software used by hundreds of users world wide
Dedicated discussion group
Citation by peer groups
Fiber Analysis
Modified plane wave methods
Galerkin method: Laguerre-Gauss, Hermite-Gauss
Compact-2D FDTD for waveguides
FDFD for arbitrary fibers

31. Related Publications
F. Wu, S. Guo, K. Ikram, S. Albin, H. Tai, B. Rogowski, “Numerical analysis of Bragg fibers using a compact 1D finite-difference frequency-domain method,” Opt. Comm. 249, (2005).
S. Guo, F. Wu, S. Albin, H. Tai, B. Rogowski, “Loss and dispersion analysis of microstructured fibers by finite-difference method,” Opt. Express 12, (2004).
S. Guo, F. Wu, S. Albin, B. Rogowski, “Photonic band gap analysis using finite-difference frequency-domain method”, Opt. Express 12, (2004).
S. Guo, F. Wu, K. Ikram, S. Albin, “Analysis of circular fiber with arbitrary index profiles by Galerkin method”, Optics Letters 29,32-34 (2004).
S. Guo, S. Albin, B. Rogowski, "Comparative analysis of Bragg fibers," Opt. Express 12, (2004).
S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect modes in photonic crystals”, Opt. Express 11, (2003).
S. Guo, S. Albin, Simple plane wave implementation for photonic crystal calculations, Opt. Express 11, 167 (2003).
S. Guo and S. Albin, “Transmission property and evanescent wave absorption of cladded multimode fiber tapers”, Opt. Express 11, (2003).

32. Acknowledgments
This research is supported by NASA Langley Research Center through NASA-University Photonics Education and Research Consortium (NUPERC)