Photonic Bandgap Photonic Bandgap StructuresStructures

ByByAkshay V. HegdeAkshay V. HegdeGraduate StudentGraduate Student

Dept. of Electrical EngineeringDept. of Electrical EngineeringCourse: Optical CommunicationsCourse: Optical Communications

Instructor: Dr. Pao-Lo LiuInstructor: Dr. Pao-Lo Liu

AgendaAgenda Photonic Band GapsPhotonic Band Gaps Photonic Band Gaps & Bragg’s LawPhotonic Band Gaps & Bragg’s Law Natural PBSNatural PBS Artificial PBSArtificial PBS Fabrication of PBSFabrication of PBS Self-Assembly ProcessSelf-Assembly Process Photonic Crystal FiberPhotonic Crystal Fiber Future ApplicationsFuture Applications Photonic GiantsPhotonic Giants

Photonic Band GapsPhotonic Band Gaps

Photons with a certain range of Photons with a certain range of wavelengths do not have an energy state wavelengths do not have an energy state to occupy in a structureto occupy in a structure

These photons are forbidden in the These photons are forbidden in the structure and cannot propagatestructure and cannot propagate

Analogous to forbidden energy gaps in Analogous to forbidden energy gaps in semiconductors semiconductors

E = (hc)/λ

Photonic Band Gaps & Bragg’s LawPhotonic Band Gaps & Bragg’s Law

Periodic objects reflect incident waves when the Periodic objects reflect incident waves when the dimensions, wavelength and interplanar dimensions, wavelength and interplanar spacing, satisfy spacing, satisfy Bragg's LawBragg's Law

Bragg’s Law Bragg’s Law is valid for any EM wave in any is valid for any EM wave in any periodic objectperiodic object

Natural PBSNatural PBS

The Gemstone Opal

Natural PBSNatural PBS

The Mitoura Grynea

Artificial PBSArtificial PBS

A lattice fabricated A lattice fabricated from layers of silicon from layers of silicon "matchsticks" "matchsticks"

Spherical air holes in Spherical air holes in a material with a high a material with a high refractive indexrefractive index

Fabrication of PBSFabrication of PBS Two popular methodsTwo popular methods

LithographyLithography Defects can be precisely controlledDefects can be precisely controlled Ideal for small scale productionIdeal for small scale production Expensive and complexExpensive and complex

Self-AssemblySelf-Assembly Defects cannot be controlledDefects cannot be controlled

preciselyprecisely Works well for bulk productionWorks well for bulk production Inexpensive and simpleInexpensive and simple

An Opal Template

Self-Assembly ProcessSelf-Assembly Process

Photonic Crystal FiberPhotonic Crystal Fiber

A long thread of silica glass with a periodic A long thread of silica glass with a periodic air holes running down its length air holes running down its length

Type 1- The central hole is absent, high-Type 1- The central hole is absent, high-index defect acts as coreindex defect acts as core

Type 2 - The core has an extra hole, Type 2 - The core has an extra hole, which is a low-index defect (Photonic which is a low-index defect (Photonic band gap fiber)band gap fiber) Light is guided along the low refractive index Light is guided along the low refractive index

air core by photonic band gap confinement air core by photonic band gap confinement effect effect

Presently, fabrication of 3D photonic Presently, fabrication of 3D photonic crystals on the scale of a micron is crystals on the scale of a micron is difficultdifficult

High-Index Defect FiberHigh-Index Defect Fiber Low-Index Defect FiberLow-Index Defect Fiber

Future ApplicationsFuture Applications

Highly efficient photonic crystal lasersHighly efficient photonic crystal lasers High resolution spectral filtersHigh resolution spectral filters Photonic crystal diodes and transistorsPhotonic crystal diodes and transistors High efficiency light bulbsHigh efficiency light bulbs Optical computersOptical computers Telecommunication & computer networksTelecommunication & computer networks Photonic clothes and candy bars?Photonic clothes and candy bars?

Photonic GiantsPhotonic Giants

NEC Research Institute & Electrical NEC Research Institute & Electrical Engineering Dept. at Princeton UniversityEngineering Dept. at Princeton University

Dept. of Electrical Engineering at UCLADept. of Electrical Engineering at UCLA Massachusetts Institute of TechnologyMassachusetts Institute of Technology Sandia National Laboratories, CaliforniaSandia National Laboratories, California Rockwell International, CaliforniaRockwell International, California Bell LabsBell Labs CorningCorning

ReferencesReferences

Articles on “Photonic Band Gap Links” (Articles on “Photonic Band Gap Links” (http://pbglink.comhttp://pbglink.com))

Physics Web (Physics Web (http://physicsweb.org/article/world/13/8/9http://physicsweb.org/article/world/13/8/9))

Optoelectronics Group, University of Bath (Optoelectronics Group, University of Bath (http://www.bath.ac.uk/physics/groups/opto/pcf.hthttp://www.bath.ac.uk/physics/groups/opto/pcf.htmlml))

Wired Magazine (Wired Magazine (http://www.wired.com/wired/archive/8.09/optical.http://www.wired.com/wired/archive/8.09/optical.htmlhtml))

Thank You!Thank You!