optics and photonics concentration
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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 Doolittlestephen.ralph@ece.gatech.edu alan.doolittle@ece.gatech.edu404 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
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