Optics and Photonics Concentration

Georgia Institute of Technology - AtlantaSchool of Electrical and Computer Engineering

Optics and Photonics

Optics and Photonics

Core Faculty Ali Adibi John A. Buck Russ Callen Gee-Kung Chang David S. Citrin Ian T. Ferguson Thomas K. Gaylord Elias N. Glytsis Bernard Kippelen Stephen E. Ralph William T. Rhodes Gisele Bennett Ben Klein

Affiliated members

Christiana Honsberg Microsystems William Hunt BioEngineering Mary Ann Ingram Telecommunications Glenn Smith Electromagnetics Ajeet Rohatgi Microsystems Steve McLaughlin Telecom Douglas Yoder Microsystems GTRIP

Primary Research Areas Optical Communication Networks

Next generation optical networks Optical networking testbeds Advanced modulation formats Optical and electronic mitigation of signal impairment Coherent and interferometric detection Equalization and coding with telecommunications faculty

Nonlinear Optics Propagation in optical fibers and nonlinear effects in semiconductors Wavelength conversion methods Propagation of ultrashort solitons, Nonlinear propagation in fiber amplifiers Continuum generation in microstructure fiber. Short pulse characterization techniques which reveal both the

amplitude and phase

Primary Research Areas

Photonics and optoelectronics Integrated sensors Fundamental investigations of new materials and nanostructures High speed optical transmitters, receivers Lithium niobate modulators with integrated drivers and detection Photonic bandgap devices: optical interconnects, signal processing,

and computing. Photonic crystals with 1-D, 2-D, and 3-D bandgap structures, for

passive and active optical devices

Diffractive and holographic optics Volume holograms for data storage (memory), 3D pattern recognition,

filtering, WDM, interconnection, and sensing Diffractive/holographic optical elements, perform functions that would

be very difficult or impossible to produce using conventional optics. Driven by fundamental improvements in modeling, design, and

optimization methods as well as advances in microfabrication technology

Quantum optical signal transmission Photon counting for long distance transmissions with very weak

optical beams (1 photon/bit) Non-linear dynamics for generating random codes for spread-

spectrum communications and multiple access networks Soliton modulation, wavelength division multiplexing Signal coding for wireless communications Efficient conversion of 2- and 3-D full-spectral image information Secure communications by means of quantum optics and chaotic

generation of random encryption keys

Georgia Tech Lorraine

Advanced Methods for Terahertz Science and Engineering

• Expand recognized RF and optical capabilities to cover Terahertz frequency region

• Support current research programs in metamaterials and EM composites characterization

• Provide advanced THz measurement resource for Georgia Tech community

• Increase RI collaborations, publications and innovations to attract new sponsored research

With Doug Denison, Mike Knotts, John Schultz, Don Creyts,David Citrin, Stephen Ralph

TERAHERTZ TECHNOLOGY

• Development of efficient sources and detectors• Understanding of THz/material interactions• Integration of semiconductor simulations with full EM

field numerical routines

• Spectroscopy of large organic molecules and composites

• Imaging for biomedicine and national security

• Supports GTRI strategic plan for growth into new technology areas

• Promotes active area of scientific research that bridges high frequency electronics and optics

• Secures new funding in biomedical research, nanotechnology, industrial process monitoring, and defense and national security applications

OBJECTIVES

RESEARCH DESCRIPTION IMPACT OF WORK

RF and Microwave IR, Optical, X-ray

TERAHERTZ

Electromagnetic Spectrum

Science EngineeringCarrier dynamics

Imaging

100 GHz 10 THz

Terahertz Science:

Terahertz Engineering:

Ultrafast Nano-Optics Theory and Simulation

David S. Citrin

School Of Electrical and Computer Engineering

Georgia Institute of Technology

Atlanta, Georgia 30332-0250

Medical imaging Biochemical sensing Security Satellite-to-satellite

communications Process monitoring Direct modulation

Terahertz technology window and opportunities

Terahertz Nonlinearities in Semiconductor Optical Amplifiers (SOA)

Time dependent carrier temperature in GaAs SOA follows THz frequency

Magneto-Optical Sensors: Semiconductor Nanorings

InAs nanorings: Petroff group: UCSB

Localized Correlators for Mode Separation in Multimode Fibers

Ali Adibi

School of Electrical and Computer Eng.Georgia Institute of Technology

Applications of Two-Center Recording

•Gated holographic recording Localized recording

Data storage

Optical elements

Conventional optical elements

Diffractive optical elements

Optical correlator

Pattern recognition

Mode separation (MM fibers)

Localized Holographic Correlators

Recording

ReferenceSensitizing

Correlation

Detector Array

Different patterns are recorded in different slices

Diffracted intensity is proportional to the correlation between the reading pattern with the recorded one

Research AreasResearch Areas

charge generationcharge generation

charge transportcharge transport

electroluminescenceelectroluminescence

optical amplificationoptical amplification

laserslasers

photorefractivityphotorefractivity

nonlinear-opticsnonlinear-optics

liquid crystal mesophasesliquid crystal mesophases

Fundamental physical processesFundamental physical processes ApplicationsApplications Organic displaysOrganic displays

Photovoltaic cellsPhotovoltaic cells

RFID tags and sensorsRFID tags and sensors

Organic field-effectOrganic field-effect transistors transistors

Organic memoriesOrganic memories

Real-time holographyReal-time holography

Electro-active lensesElectro-active lenses

Imaging Imaging

Organic PhotovoltaicsOrganic Photovoltaics

Bottom-up approach to photovoltaic cells on light weight flexible substrates

Develop new organic semiconductors with high mobility

Use self-assembly to produce highly ordered thin films

Organic ElectronicsOrganic Electronics

Low temperature processing Low temperature processing of organic semiconductors, of organic semiconductors, metals and dielectrics on metals and dielectrics on flexible substrates: low cost flexible substrates: low cost ($0.01)($0.01)

Metal deposition on plastics Metal deposition on plastics from solution, micro-size from solution, micro-size features using soft lithography features using soft lithography

MacroelectronicsMacroelectronics

RF identification tagsRF identification tags

Electronic paperElectronic paper

Active matrix drivers Active matrix drivers

Organic DisplaysOrganic Displays

Developed photo-patternable hole transport polymers that can be processed like a photoresist; provides easy patterning for color displays.

RGB active high luminance at RGB active high luminance at low voltage, processing at low low voltage, processing at low temperature on flexible substrates temperature on flexible substrates

Chem. Mater. 15, 1491 (2003)

Holography and Holography and Imaging Imaging Thick phase recording media for real-time Thick phase recording media for real-time

holography, large dynamic range and holography, large dynamic range and video rate compatible response timesvideo rate compatible response times

Holographic storage

Optical correlators

Dynamic holograms

Image processing

Medical Imaging

Optical testing

Novelty filtering

Phase-conjugation

Nonlinear Optics & PhotonicsNonlinear Optics & Photonics Organic electro-optic materials and devices

Frequency conversion

Tunable filters and routers

Tunable optical delay lines

Amplifiers and lasers

Short pulse diagnostics

Integrated waveguide and microring resonator devices

Optical Networking Group Goals

• Establish Optical Networking Research Laboratory• Next Generation optical network architecture and applications

• Design and Build Next Generation Optical Internet Testbed

• Enabling Photonic System Technology Research• Advanced transmitters, receivers, modulation techniques• All-optical wavelength, space, and time switches• Tunable optical delay, optical label, and burst mode payload receivers• Compensation techniques for fiber transmission impairments

• Control and Management of Optical Routing Network• Broadband access technology for bandwidth-on-demand, low-latency

symmetric customer services.• OLS and GMPLS control plane and management interface

• Routing protocol and contention resolution algorithms

• Enhanced Intelligent Networking Services and Operations• Agile dynamic service creation, provisioning, and protection/restoration

• Flexible burst switching service with flexible bandwidth granularity

• Build a National Research Testbed Consortium • Lead communications research institutions

• Enhance and build upon National Light (Lambda) Rails

WDM

RWA

WDM

RWA

WDM

RWA

WDM

RWA

ADM ports

IP/MPLS

ADM ports

IP/MPLS

ADM ports

IP/MPLS

ADM ports

IP/MPLS

OLTSplitter/Combiner

ONU

ONU

ONU

ONU

Core NetworkNode

Edge NetworkNode

Edge Network Node

Access Network

OLT

Splitter/Combiner

ONUONU

ONU

Wavelength Interchange

IncomingOpticalTraffic

Optical labelExtractionN’s

per Fiber

NC

&M

Routing Engine

Forwading Engine

OutgoingOpticalTrafficOLS

Switching Fabric

Client Interface Processor

GbE

POSO

C-X

Backplane

OLSR: Optical Label Switching Router

RWA: Routing and Switching Assignment

OLSR

Access Network

WDM

RWA

Optical RouterArchitecture

Broadband Optical Networking Testbed Research in Georgia Tech

Georgia Tech Confidential

Building Optical Networking Testbed in GCATT

Promoting Optical Networking for Next Generation Internet

BellSouth Network Service President and CTO

Fully Integrated Chem/Bio Sensing

Development of interferometric chemical and biological “wet” and gas sensors integrated directly with on-chip electronics for intelligent sensors

The key to this research is the design and fabrication of biological and chemical interferometric sensors integrated in three dimensions (3D) directly on top of Si CMOS VLSI detector and signal processing circuitry

The challenge for this integrated system is to demonstrate high sensitivity detection in a miniaturized, short Si CMOS on-chip size, and species discrimination in a rugged, low power, portable formatSilicon PiN diode array for modal image analysis

Sigma-Delta “analog to digital” converters

Heterogeneous integrated laser sources

Multimode Interferometer/CMOS detection and signal analysis

Interferometer Structure

Sensing Layer: Detects organics, i.e. benzene,

trichloroethylene

Compatible with electronics fabrication and processing

Chemically resistant

Reusable (reversible sorption or organics)

Effective up to 250 °C

Index of refraction = 1.59 – 1.61 (l = 850 nm)

Available dissolved in solvent for spin coating

Silicon Substrate, n ~ 3.6538, k ~ 0.004177

SiO2 cladding ~2 m, n ~ 1.4734, k ~ 0

Si3N4 ~0.2 m,

n ~ 1.9218, k ~ 0

Novolac ~1 m, n ~1.60

SensingReference

A Platform Technology for the Integration of Semiconductor Electronic Devices with Nonlinear

Optical Materials

Stephen E. Ralph W. Alan [email protected] [email protected] 894 5168 404 894 9884

Georgia Institute of TechnologySchool of Electrical and Computer Engineering777 Atlantic Drive Atlanta GA 30332

Dense Epitaxial Integrated Optics

LiNbO3

Electrodes Epitaxial III-Nitride

Ti diffused/strip loadedwaveguides

Epitaxial AlN buffer

Georgia Tech has developed a materials growth technology which allows the epitaxial integration of AlGaN semiconductors with the most widely used nonlinear-electro optical material, Lithium Niobate

This technology enables: Integrated control of phase and amplitude of optical signals Advanced modulation formats exploiting phase, commonly seen in wireless Interferometric transmitters and receivers Integrated detection at 1500nm via use of InN detectors

Monitoring of Extinction ratio Dynamically adaptable bias point control Dynamic Chirp control Pulse shaping

Signal processing circuits

Process Protection SiNX

Modulation doped AlGaN cap

Undoped GaN

“Special” AlN

Z-cut LiNbO3 Ti-diffused wafers

Waveguide Electrodes

Waveguides

Source Gate Drain

Process ProtectionSiNX

Modulation dopedAlGaN cap

Undoped GaN

“Special”AlN

Z-cut LiNbO3 Ti-diffused wafers

Waveguide Electrodes

Waveguides

Source Gate Drain

•Students have been trained and have successfully completed 7 out of 16 process steps.

•Aggressive small geometry lithography and metallization (1-4 um) successfully demonstrated.

Gate Drain

Source

SourceDrain

Mesa

Progress in Device Processing

•New students began training and clean room qualification (~3 month process) in fall 2003.

•Effort leveraged by engineer supported outside of GTBI program.

B.R. Washburn, S.E. RalphSchool of Electrical and Computer Engineering

Georgia Institute of Technology

P. A. Lacourt, J. M. Dudley, W. T. RhodesGTL-CNRS Telecom, Georgia Tech Lorraine

S. CoenService d’Optique et Acoustique, Université Libre de Bruxelles

R.S. WindelerBell Laboratories, Lucent Technologies

Soliton Generation via Intrapulse Stimulated Raman Scattering in Photonic

Crystal Fibers: Experimental and Numerical

Investigations

Geometry of the Photonic Crystal Fiber

• PCF comprised of a hexagonal lattice of air-holes and glass

• The “core” is a defect in the lattice: glass where a hole should be

• PCF exhibits a reduced fiber core size compared to standard fiber

• The effective nonlinearity (W m) is eight times larger than in standard fiber at 800 nm

• Specific geometry exhibits zero group velocity dispersion at 767 nm

2020ncrω≡π

Supercontinuum Generation in PCF

600 700 800 900 1000 1100 1200 1300 1400

10-5

10-4

10-3

10-2

10-1

100

Supercontinuum Generation

Input Ti:sapphire spectrum

Spectral Intensity (a.u.)

Wavelength (nm)

Dramatic spectral broadening due to multiple nonlinear effects (SPM, FWM, SRS) occurring simultaneously

Dominant mechanism depends on peak power, pulse width and dispersion and fiber length

Spectral width of 1000 nm, which covers all visible wavelengths

Cooperative Signal Processing for Equalization

Stephen E. Ralph and Steve MclaughlinSchool of Electrical and Computer Engineering

Fabricated Device

Two-segment metal-semiconductor-metal (MSM) device fabricated InGaAs and GaAs demonstrated Ease of manufacture 50-m inner detector radius

Scalar weighting is implemented by applying dual-biasing “Polarity” of detected signal is related

to polarity of bias voltage

Maintains the simplicity of a conventional photodetector

Vo

Vcc

-Vcc

Vcc

Vo

Vcc

-Vcc

Separate Detection RegionsOptical

Fiber

Channel Impulse Response

= 810 nm

= 1550 nm

= 810 nm

= 1550 nm

Simulation Measurement

Measured with ~1-ps @ 1550-nm or ~20-ps @ 810-nm Assume incoherent interaction among modes are output Fiber: 1.1-km silica MMF with 50-m graded-index core

Simulation parameter of fiber based on manufacture specs

Simulated Eye-Diagram over 1.1-km MMF

Emulate MMF link by using measured MMF impulse response with conventional PD

Emulate MMF link by using measured MMF impulse response with SRE enhancement

200 MHz-km @ 810-nm 500 MHz-km @ 1550-nm

1250-Mbps @ 1550-nm

1250-Mbps @ 1550-nm

600-Mbps @ 810-nm

600-Mbps @ 810-nm

Measured 1.25-Gbps Link

Link with 1.1 km, 50-m, GI-MMF PRBS at 1.25-Gb/s

Externally modulated 1550-nm FP laser source with mode-scrambler Overfilled-launch into fiber

Dramatic reduction in ISI with SRE Improvement in amplitude and phase margin Complete closure of eye otherwise Works synergistically with restricted

illumination condition

Measured Bit-Error-Rate

* includes penalty associated with non-optimized performance inherent to receiver (PD responsivity, TIA noise, PD-TIA response)

For 1.1-km link, >10-9 BER at 1.25 Gbps is achievable with SRE With standard detection, ISI renders link unusable

Despite SRE loss, sensitivity required for 1000-LX Ethernet is achievable Back-to-back; accounting for penalty due to non-optimal device fabrication

1.1km MMF Link Performance @ 1.25 Gbps

DFE = 5 forward taps, 5 backward tapsDFE = 5 forward taps, 5 backward taps Viterbi = 16 states, 20 bits decoder depth

Combined techniques “SRE+DFE” and “SRE + Viterbi” shows unique capabilities of an integrated Photonic/Electrical Approach pioneered at Georgia Tech

Near total compensation of DMD is possible