csio chandigarh
TRANSCRIPT
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NOVEL MATERIALS FOR FUTURE; NANOCOMPOSITES FOR PHOTONICS
SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH19, UNIVERSITY ROAD, DELHI-110 007
Email : [email protected] Website : www.shriraminstitute.org
Presented by :Dr. R.K. KHANDAL
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Outline of the Presentation
Photons & PhotonicsDefinition
Properties
Interaction of electromagnetic radiation with matter
Need for novel materials
Evolution of optical system technologies
Materials
ApplicationsComposites for Nanophotonics
Confinement of Energy
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PHOTONICS
Photons
Interactions of electromagnetic radiation with matter
Photonics
Optical phenomena
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Photons: Relevance
What are photons ? Omnipresent source of vital energy
What is the relevance?
Carrier of InformationWhat is energy ?
Using the Vital Energy to get Vital Information
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Photons: Basic properties
Zero electric charge & no rest massEnergy & momentumDual nature (wave & particle)
Not be destroyed / & created
Produce effects, i.e. photo-electric, compton & ion-pair
Photons have:
Photons can:
Zillions of photons in an ordinary light beam
Interactions of photons with matter (materials) is the key!
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Interactions of electromagnetic radiations with matter
Matrix
e-
Photoelectric Effect
Matrix
e-
Compton Scattering
Matrix
Pair Production
e-
e+
Transfer of all energy of photon to electron
Elastic collision of photons with atomic electrons
Ionization Momentum to target electron
K.E of a photon
2 new particles with K.E
Formation of electron & positron
Photodiodes, sensors photomultipliers, Image transistors
Radiobiology, Radiation therapy Stellar explosions
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7
Metals with small Atomic No. Photoelectric effect CE observed at energy Energy range for CE Energy required for PP
Metals with higher Atomic No. Photoelectric effect CE observed at energy Energy range for CE Energy required for PP
Photoelectric effect (PE) Dominant
Pair production
(PP) Dominant
Compton effect (CE) Dominant
0.10.01 10 100
Ato
mic
No.
of
the
targ
et
0
20
40
60
80
100
120
1Photon incident energy (MeV)
Interaction of Electromagnetic Radiation with Matter
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Effect of penetration depth on absorption of photons
D = 1/ D = Mean penetration depth = absorption coefficient
Majority photons will be absorbed / scattered before reaching D
Many will penetrate farther than D
Data are for D = 2
Majority of photons donot penetrate upto DTangent at x = 2 extends to intersect the zero transmission
axis at x = 4 i.e. at a depth of (x + D)27Intensity falls to 0.37(36.8%) at x = 2
Thickness extends to 5 x DExponential
absorption of photons by
matter
Development of materials by maneuvering penetration
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Interaction of electromagnetic radiation with matter: Linear Optical Phenomena
Refractive Index (R.I.)
Dispersion (Abbe Number)
During interaction with light, the refractive index & other properties remain constant throughout the medium
Linear optics is a material & energy dependent property
Devices: Lenses Filters Coatings
Low HighMid
1
2
i
r
= sin i sin r
<1.5 1.5-1.6 >1.6
PC,Glass
PA, Glass
Thiourethanes, Glass
30- 60 Glass, Plastics
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Difference frequency mixing (DFM)Mixing of different wave frequencies to form a coherent beam (e.g. LiNbO3, BaBO3, Poly (p-phenylene vinylene)
Four wave mixing (FWM)Channel spacing can be achieved (e.g. LiNbO3,
BaBO3, Poly (p-phenylene vinylene)
Behavior of light in nonlinear media in which the dielectric polarization P responds nonlinearly to the electric field E of the light
Change in refractive index (Δn) directs light to travel in required directions All are essential for fiber optics, optical switches, waveguides Devices based on above phenomena have the capability to switch speeds
from 1 ns to less than 1 ps Materials with both high non-linearity and low loss are required
Transmission
Generation
Modulation
Cross-phase modulation (XPM)Technique for adding information to a light stream by phase modification of coherent optical beam (e.g. LiNbO3, BaBO3, Poly (p-phenylene vinylene)
Interaction of electromagnetic radiation with matter: Non-linear Optical Phenomena
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Waste Disposal (Pharma) : Energy - Efficient Technology
Plasma gasification technology eliminates the need for landfills
Pharma waste
Plasma Thermal Destruction &
Recovery
Syngas Vitrified products
Recovered metals
Electricity
Steam
Liquid fuels
Concrete aggregates
Construction
Tiles
Metal
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Waste Disposal (Textiles) : Waste - to - Wealth Technology
Value-added product from textile sludge: Bricks
Cost-benefits to textile & construction industries
Textile sludge
Construction Industry
Efficient management
Useful by-product
Economic benefits
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PhotonicsPharma waste
Plasma Thermal destruction &
recovery
Syngas Vitrified products
Recovered metals
Electricity
Steam
Liquid fuels
Natural gas offset
Concrete aggregates
Roadbed/fill
Construction
Tiles
Metal
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Photonics
Detection
Transmission
Generation
Amplification
Semiconductors, LED,s -OLED,s, Lasers, Super luminescent diodes, Cathode ray tube, Fluorescent lamps
Glass fiber, Optical fiber, Photonic crystals, Photonic crystal fibers, Meta materials
Optical amplifier: Doped fiber amplifier Semiconductors
Raman Amplifier Quantum dot
Photo Thermal
Chemical Photoelectron
Modulation
Optical modulator Electro absorption modulator On-off key formats
All devices would need materials
Components Dimensions
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Technology
Components
Materials
Alignment
Propagation
Device size
Evolution of optical systems technology
Ist Generation
ConventionalOpticsMirrors, prisms,lenses, gas lasers
Glass
Necessary
Beam
1 m2
IInd Generation
Micro-Optics
LED, LD, tinylenses, optical fibersGlass & polymers
Necessary (hard)
Waveguides
10 cm2
IIIrd Generation
Integratedphotonics
Monomode channel
waveguides,
LD
Composites
Unnecessary
Waveguides
10 cm2
Development of new materials leads to new devices & vice-versa
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Electronic signal
Light signal
Processing of light
Light signal
OPTICAL-ELECTRONIC-OPTICAL
More signal losses
Light signal
Light signal
OPTICAL-OPTICAL
Less signal lossesFast speed
Detection
Detection
Present focus is more towards optical (OO) conversion of light
Current telecommunication systems combine both electronic & optical data transmission; emphasis is to move towards all optical networks due to increased bandwidth
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C H 3
H 3 C ON O 2
N ( C H 3 ) 2
N +C H 3
H 3 C S O 4-
N
N
C H
C N
C N
S O 3-H 3 C
N ( C H 3 ) 2
N +C H 3
Materials for non-linear optics
3 methyl-4methoxy-4-nitrostilbene
4’-dimethylamino-N methyl-4-stilbazolium methyl sulfate
3-(1,1-dicyano ethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole
4’-dimethylamino-N methyl-4-stilbazolium tosylate
Synthesis of conventional organic optical materials is cumbersome & expensive; incorporation into optical devices is problematic
Need for alternative materials, such as nanocomposites, exists!
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NH4H2PO4 Ammonium dihydrogen phosphate
Ba(BO3)2.nH2O Barium metaborate
KH2PO4 Potassium dihydrogen phosphate
LiNbO3 Lithium niobate
Incorporation of inorganic optical materials in polymers would lead to enhanced properties of nanocomposites
Materials for non-linear optics
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Approaches
Semiconductor Optical Amplifiers (SOA)
Manufacturing photonic band gap structures with non-linear materials
Enhancement of non-resonant optical non-linearity using local-fields effects
Developing new crystalline & polymeric materials with high optical non-linearity
InP is used; expensive; coupling problems
Yet to build capabilities
Enhancement factors of only 10 times has been achieved so far
PTS & Polyacetylene LiNbO3 - Promising materials; expensive & difficult to process
Status
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Desired Properties for Photonic Applications
Low optical loss due to absorption or scattering Linear index of refraction Large difference in refractive index High non-linearity & processability Physical & Chemical compatibility Low cost of manufacturing
Extremely difficult to find a pure material meeting he above criteria
Nanocomposites are promising materials for achieving desire properties
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NANOCOMPOSITES PHOTONICS
Dimensions & confinement
Materials
Designing Composites
Fabrication
Types
Metamaterials
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Applications of Photonics Nanocomposites
LEDFiber Optics
PhotovoltaicsOptical Amplifiers
Optical Switches
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Three areas of Nanophotonics
Photonic crystals
Metamaterials
Confined semi-conductors
Photonic crystals & confined semi-conductors form the basis of nanophotonic composites
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Dimensionality of Photonic Materials
One dimension Two dimensions Three dimensions
Flow of electromagnetic waves can be controlled by periodic variation of refractive index & dielectric constant
Designing & tailoring the key properties of polymeric materials is important for technological advancements
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Refractive Indices of Materials
High refractive index materials are preferred materials
Inorganic materials: Brittle and difficult to process
Polymers: Desired for better physical properties
Inorganic nano-particles: Improvement in R.I. of polymers
Ge (633 nm) 5.5
Si (633 nm) 3.8
Air 1
Polysulfone (589 nm) 1.63
Polystyrene (589 nm) 1.59
Polypropylene (589 nm) 1.51
TiO2 (589 nm) 2.34
ZnS (589 nm) 2.43
CdS (589 nm) 2.50
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Confinement- Energy vs Size
1 2 3 4 5 6 7 8 9 10
Size (nm)
En
erg
y
Energy gap shifts as a function of size (quantum confinement) Band gap energy size Energy of the emitted light size By careful control of size, fine tuning of optical & electronic
properties are possible Quantum confinement effects of semiconductor materials is
being exploited in the areas of catalysis & photonics
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3 . 1 4
3 . 2 93 . 2 8
3 . 2 1
3 . 1 2
3 . 1 4
3 . 1 6
3 . 1 8
3 . 2 0
3 . 2 2
3 . 2 4
3 . 2 6
3 . 2 8
3 . 3 0
5 1 0 1 5 2 0
P a r t i c l e s i z e ( n m )
Ba
nd
ga
p e
ne
rg
y(e
V)
Size Vs Energy of TiO2 nanoparticles
Effect of particle size on the band gap energy of TiO2 finds applications in optical devices & catalysis
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Ways Of Confinement
Confinement of Photon Confinement of Electron
Quantum well
Quantum wire
Quantum dot
Optical planar waveguide
Optical fiber
Microsphere Optical cavity
Application: Telecommunications Application: Semiconductor devices
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Challenges-Synthesis -Specialized conditions-Commercial viability
Confinement of matter is the most viable option having wide applications !
Polymers are the only materials which confines radiation, matter & process at the nanoscale.
Criteria RequirementA Confinement
of radiation at nanoscale
- Quantum dots
- Quantum wells
- Quantum wire
B - Nanosized particles
- Established Methods (Physical & chemical)
- Wide Option of material (Inorganic & organic)
- Commercial products (Sunscreen lotions, filters) are available
C- Energy distribution (Photonic band gap)
- Nanofabrication- Intergrated Circuits
- Sensors & actuators
Status- Ongoing Research
- Large scale manufacturing
Confinement of matter at nanoscale
Confinement of processes at nanoscale
Confinement at Nanoscale
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Defining Nanocomposites
Dispersed phase
Continuous phase
Quantum dots
<10 nm
Nanoparticles
~ 10-50 nm
Acts as a scattering medium through which light transmission can be manipulated to produce various photonic functions
Comprising of quantum dots & nanoparticles dispersed in a suitable polymer are novel materials for photonic applications
Bulk properties of the material, such as R.I. can be modulated Tailor making of optical & electronic properties can be achieved
by the appropriate combination of particle size & type of material
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Solid Waste Disposal : Scale of Eco-friendliness
Value addition
Reuse
Prolonging life-cycle
Regeneration
Modifications
Cradle - to - Grave utility
Land- filling
Getting Rid-off
Recycling
FuelMinimum effort & best useE
co
-fr i
en
dli n
es
s
Nothing is a waste means complete eco-friendliness
Scale of Eco-friendly practices of the waste disposal :
Utility-centric Safety-driven Regeneration-specific
Disposal-centric practices are non eco-friendly
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Drilling waste
Petroleum SludgeElectro-kinetic transformation
Bio-treatment Compost material
Value-addition
Application of electro-kinetics to petroleum sludge increases hydrocarbon recovery Economic benefit
Oil contaminated soil
Petroleum WasteRecycling of H/C
residue
Cost-effective
Porous ceramic articles
Waste Disposal (Petroleum) : Eco-friendly Practices
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Nanocomposites
Dispersed phase
Continuous phase
Particle size < λlight
NANOCOMPOSITES
Particle size > λlight
Less light scattering
E.g. Waveguides
More light scattering
E.g. Laser paints
The optical interactions within & among the particles can be controlled to derive a specific photonic response or multifunctionality
Each particle performs specific photonic or opto-electronic function
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Preparation of Photonic Nanocomposites
Incorporation
Liquids
Vapor deposition
Solids Glasses Polymers
Ion-implantation
Homogeneous films
Quantum dots
Bulk
Sound energy, Light energyElectrical energy, Thermal energyChemical energyMagnetic energy
Top down & bottom up approaches are commonly used to prepare quantum dots of varying sizes
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Designing Composites: Basic Principles
Periodic arrangement of R.I. variation controls movement of photons New energy levels within the band gaps can be created by breaking the
periodicity of the photonic material by enlarging, reducing or removing voids; the desired change in refractive index can be achieved by modifying the voids
Wavelength selective structures can be formed by careful selection of symmetry & spacing
Modification of light propagation takes place through enlarging, reducing or removing voids; optical cross-connects, switches & waveguides
Photonic band gap: Restricts transmission of light to defined set of bands
Voids
Enlarged voids Reduced voids Voids removal
Matrix
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OO
O
*
O
O O *
Polycarbonate APC
Amorphous
Tg = 183oC
R. I. =1.54
Criteria for an EO-polymer to be used in tuneable nanophotonic devices: It has to form low loss (low absorption & low scattering) film
Tg should be >140oC
High EO-coefficient to allow a strong variation of the transmission characteristics of the photonic structure
High concentration (20 wt. %) NLO-chromophore
Fabrication of a Photonic Nanocomposite System-1
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Fabrication of Photonic Nanocomposite System-2
Modification of light propagation takes place through enlarging, reducing or removing voids; optical cross-connects, switches & waveguides
Addition of monomer
PolymerizationRemoval of
colloid spheres
FCC single crystal Partial fusion of colloids
Dedoping of polythiophene
n1 = 2.9 n2 = 1
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Chemical bonding to surface
Fabrication of a Photonic Nanocomposite System-3
Surfactants
Nanoparticles
Expensive & specialized equipment not required Chemical bonding provides stability & robustness Easily implemented
Inorganic materials
Surface Functionalization
Dispersion
FilmsProcessing
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Cool (-20°C)
Fabrication of Photonic Nanocomposite System-4
Heated (60 °-280°C/ 48 hrs)
Mg powder (0.05-2 mol)
End capping (phenyl lithium)
SiCl4 (0.05-0.2 mol) Dropwise addition
Dropwise addition
Quenched (dil. Protic acid)
Stirring/ 48 hrs
Extract/precipitation/drying
Dispersion in PMMA Film Casting
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Mixture
Fabrication of a Photonic Nanocomposite System-5
Paste
Nanopigment (TiO2, ZnO)
Siloxane
Liquid paraffin
Anti-sun protection milk
Stirring/40ºC
Milling
Filler (SiO2, B3N, PMMA powder)
Oil in water emulsion
Water-Glycerol +propyl p-hydroxybenzoate
Stirring/80ºC
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Two Dimensional Polymeric Photonic Band Gap
P2VP + PI + Polystyrene
Periodic dielectric structure (waveguide)
CdSe Crystallites (SM- trioctylphosphine oxide)
Block co-polymer
Roll cast
Mixed
120oC & vacuumAnnealed
Fabrication of a Photonic Nanocomposite System-6
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Metamaterials
=µrr
Metamaterials are engineered to have EM responses which are impossible in naturally occurring materials
1
2
1
2
+ve R.I.
-ve R.I.
Refractive Index
=µrr
µr: Permeability to magnetic fieldr: Permeability to electric field
• µr, r= -ve
• Induced phenomena
µr, r= +veNatural phenomena
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Metamaterials
Kinetic stability
Metamaterials allows one to harvest properties, derived from the phase that is thermodynamically not stable.
Thermodynamically unstable
Thermodynamically metastable
Thermodynamically stable
Too slowmetamaterials
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Nanocomposite metamaterials
SiO2/V2O5
Interdispersed polymer with glass phase
Insoluble once formed
PPV precursor
Sol-gel
Hydrolyze
PPV-polymer with SiO2 network
PPV-glass composite exhibits high optical quality compared to pure PPV
Used in holographic gratings to filter out light of 50 pm bandwidth21
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SRI’s EXPERIENCE
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SRI’s Experience
SRI has experience in
High, mid and low refractive index materials
Nanocomposites for optical applications
Modification of low refractive index materials
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47474747
Refractive index increases with increase in percentage of metal salt.
1.41
1.42
1.43
1.44
1.45
1.46
1.47
1.48
0 5 10 15 20 25 30Metal salt (% by wt)
Ref
ract
ive
Ind
ex
Barium Hydroxide Lead Monoxide Lanthanum Oxide
Effect of dispersion of metal salts on the refractive index of acrylic acid
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48484848484848
Modification of low refractive index materials
The refractive index of low refractive index materials increases from 1.49 to 1.66
1 . 4 1
1 . 4 7
1 . 5 3
1 . 5 9
1 . 6 5
1 . 7 1
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0
% o f a d d i t i v e
Ref
ract
ive
ind
ex
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494949494949
Effect of metal on refractive index
In-situ formation of nanoparticles of TiThe refractive index of the polymer increases
from 1.45 to 1.53
1.44
1.46
1.48
1.5
1.52
1.54
0 2 4 6
% Ti
Re
fra
cti
ve
Ind
ex
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0 . 0 0
0 . 5 0
1 . 0 0
1 . 5 0
2 . 0 0
2 . 5 0
3 . 0 0
3 . 5 0
4 . 0 0
2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 0W a v e l e n g t h
Ab
so
rba
nc
e
M G A
B C
Semiconductors are used to prepare nanocomposites with enhanced photocatalytic activity
Dye
Nanocomposites & dye degradation
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Nanocomposites lead to complete degradation of dyeUseful for the treatment of dye effluents
91.29 92.30 94.49
37.29
86.61 87.19
0
20
40
60
80
100
A B C
Deg
rad
ati
on
rate
(%)
Nano
Normal
Nanocomposites for dye degradation
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Dye solution
Nanocomposite
Dye removal
Swelled nanocomposite after uptake of dye
Dye removal from effluent
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THANK YOU