Photonic Crystals Photonics Research Laboratory Department of Electrical and Computer Engineering Old Dominion University, Norfolk, VA 23529 http://www.lions.odu.edu/~salbin/Photonics/

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

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:

No EMAG Radiation Inside PBG

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

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

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

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

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

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

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, 1080-1089 (2003)

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, 1080-1089 (2003)

Field Profile – Single Defect S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect modes in photonic crystals”, Opt. Express 11, 1080-1089 (2003)

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

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

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

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

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

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

Add/drop channels using CCWs X S. Guo, PhD Dissertation, ODU, 2003

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

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)

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)

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

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

Air-guiding PCFs

Bragg Fiber with Omni-Reflector Omnidirectional Mirrors

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

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

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

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, 165-174 (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, 3341-3352 (2004). S. Guo, F. Wu, S. Albin, B. Rogowski, “Photonic band gap analysis using finite-difference frequency-domain method”, Opt. Express 12, 1741-1746 (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, 198-207 (2004). S. Guo, S. Albin, “Numerical techniques for excitation and analysis of defect modes in photonic crystals”, Opt. Express 11, 1080-1089 (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, 215-223 (2003).

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