5. integrated optics and molecular films ufrgs/tutorial 4.pdf · characterization and applications...
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5. Integrated Optics and Molecular Films
Characterization and Applications of Molecular Films
Surface immobilization can affect: binding affinity bio-specificity reaction rates
Impact on several technologies: biosensors bio-materials for medical implants catalysis affinity chromatography
=
Signal Enhancement for Studies in Monolayers and Sub-Monolayers
10,000
1
10
Transmission
ATR
5 mm
ATR with a single-mode integrated optical waveguide
500 nm
4
1010tcTA
9899T
log
%.
Interrogation with Integrated Optical Waveguides
4
10log 10
trA T c t
2
0
2
t
wg
tr
E dzA L
SA t
E dz
10+4 = 10+7 10-3
Atr
Awg t
L
Sensitivity Factor
water, nc = 1.33
glass, nw = 1.56
silica, ns = 1.46
2 22 w st n nV
L
Broadband Spectroscopy of Molecular Sub-Monolayers
UV-Vis Spectroscopy
≈ 200 nanometer
≈ 3 nanometer
≈ 1 millimeter ≈ 34 millimeter
Low-Loss Optical Waveguides in the UV-Vis Spectral Region
Materials Deposition Processes
- SiO2, SiOxNy
- MgF2, CaF2, BaF2
- fluoropolymers (cytop) - Al2O3
- e-beam evaporation - RF magnetron sputtering - ion-beam sputtering - sol-gel
- atomic layer deposition
• Covalent growth • Self-limiting • Conformal coating • 0.1 nm/cycle
=
trimethyl aluminun precursor
water precursor
Atomic Layer Deposition:
number of cycles
1.60
1.62
1.64
1.66
1.68
1.70
1.72
1.74
1.76
1.78
1.80
200 400 600 800 1000
Wavelength (nm)
refr
ac
tiv
e in
de
x
UV light (325 nm) propagating along a single-mode IOW for 34 mm and out-coupling
ALD Al2O3 Film for UV-Visible Single-Mode IOW
Broadband Coupler for Waveguide-based Spectroscopy
iin
sineff i iN n m
Grating-Coupler & Optical Beam with Large Numerical Aperture
sin 2 . .i in N A
central effN
central 2central
2central
Solid-Immersion Lens for Large NA
• Aplanatic (aberration free) • Highly Anamorphic (line beam)
Pereira et al.
3) Ion Milling Etching 4) Surface-Relief Grating
1) Holographic Exposure
He-Cd 442 & 325 nm
Loyd’s mirror
2) Photoresist Development
He-Ne = 632.8 nm
detector
photoresist
developer tank
Sub-Micron Surface-Relief Grating
Experimental Setup
IOW UV-Vis Spectra: down-to-300-nm
358 femto-moles/cm2 4.65 ng/cm2
1.6% of a full monolayer
cytochrome c
≈ 34 millimeter
limit of detection ≈ 1 pg/cm2
Mendes et al., Optics Express 15(9), 5595-5603 (2007)
Changes in Protein Conformation at Very Low Surface Coverage
Surface-Adsorption of Chlorophyll a
Effects of: • Salt Concentration • Surface Hydrophobicity
hydrophilic hydrophobic
10 mM NaCl
1 mM NaCl
Surface Hydrophobicity
Ionic Strength of Solution
• 1.4 µM of chlorophyll a • phosphate buffer, pH = 7.2
1 mM NaCl
10 mM NaCl
1 mM NaCl
10 mM NaCl
Hydrophilic Hydrophobic
Opt Eng, July 2011
TM TE
Polarized Spectroscopy for Molecular Orientation
ATE, ATM
What if we don’t know all the details in the waveguide ?
Isotropic calibration
Sample being studied
2222
22222
2
2cos
cTMnormcTM
cTMnormcTM
nNnN
nNnN
isotrTM
isotrTE
sampleTM
sampleTE
isotr
sample
norm
AA
A
A
,
,
,
,
1.03.0cosP2
Isotropic Sample
Molecular Orientation with Polarized Guided Waves
Fluorescence Excitation for a Cholera Toxin
Biosensor donor acceptor
Cholera Toxin
Kelly et al., Optics Letters 24, 1723-1725, (1999)
Monochromator
Detector
with Los Alamos Nat Labs
Higher Level of Device Integration, Lower CO$T
Price: $446.00
Source: Thorlabs, Inc. http://www.thorlabs.com
Integration is highly needed in the opto-electronic industry !!
Price: $38.50 Price: $58.85
78% for alignment and packaging
Evanescent Coupling in Planar Optical Waveguides
θc
z
θc
nhigh
nlow
Array detector
Presence of evanescent fields strongly affect
the spatial emission profile of
radiating dipoles !!!
bound modes
substrate
substrate radiation modes
cover-substrate radiation modes
waveguide cover
Once the fluorophores are excited, where the power goes?
z
x
22 2. i iW E E
2
,
2
, ,
2 y m
m f m eff m
E z
E h
2 2
0
2
2
2
0
2 ( , )s cn n
y s
s
s s
E z kdk
E k
2 2
2
2
2 2 2
2 ( , )s
s c
n
y s
s
cn ns s c s
s
E z kdk
kE k E k
k
TE modes
bound modes:
substrate radiation modes:
cover-substrate radiation modes:
TM modes
bound modes:
substrate radiation modes:
cover- substrate radiation modes:
2
,
2
,0,2
0
12
y m
m f m
eff m
f
dH z
z dz
Hh
n
2
,
2
,0,2
0
2 my m
m f m
eff m
f
H zz
Hh
n
2 2
0
2
2
2
0 0
2
0
,12s c
y sn n
s
s s
s
dH z k
z dzdk
H k
n
2 2
0
2
2
2
0 0
2
0
2 ,s c
sn n
y s
s
s s
s
kH z k
zdk
H k
n
0
2 2
0
2
2
2 22 0
2 2
0
,12s
s c
y sn
s
s s c scn n
s s c
dH z k
z dzdk
H k H kk
n k n
0
2 2
0
2
2
2 22 0
2 2
0
2 ,s
s c
sn
y s
s
s s c scn n
s s c
kH z k
zdk
H k H kk
n k n
Fluorophore location:
1
h
z
h
1.33
1.56 1.46 WTE+WTM
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
Bound modes
Substrate modes
Cover-substrate modes
Sum of all modes
Refractive index
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
Bound modes
Substrate modes
Cover-substrate modes
Sum of all modes
Refractive index profile
2 WTM
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
teBound modes
Substrate modes
Cover-substrate modes
Sum of all modes
Refractive index profile
2 WTE
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
h = 3.6 lambda
h = lambda
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
h = 3.6 lambda
h = lambda
Dependence on WG thickness
single-mode
multi-mode ( , 4 modes)
( )h
nf = 1.56
3.6h
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
h = 3.6 lambda
h = lambda
bound modes
sum of all modes
substrate modes
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
h = 3.6 lambda
h = lambda
cover-substrate modes
Dependence on WG refractive-index:
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
nf = 2.30
nf = 1.56
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
nf = 2.30
nf = 1.56
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
nf = 2.30
nf = 1.56
bound modes
sum of all modes
substrate modes
single-mode (nf = 1.56)
multi-mode (nf = 2.30, 4 modes)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-4 -3 -2 -1 0 1 2 3 4 5z/h
sp
on
tan
eo
us
em
iss
ion
ra
te
nf = 2.30
nf = 1.56
cover-substrate modes
1
h
2s
2wg nn
h2V
Surface-immobilized fluorophores: thickness dependence
h
cover (nc = 1.33)
waveguide (nwg = 1.56)
substrate (ns = 1.46)
2s
2wg nn
h2V
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
0 2 4 6 8 10 12 14 16 18 20
Sp
on
tan
eo
us
em
iss
ion
ra
te
Bound modes
Substrate modes
Cover-substrate modes
Sum of all modes
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0 2 4 6 8 10 12 14 16 18 20
Sp
on
tan
eo
us
em
iss
ion
ra
te
bound modes
20%
Surface-immobilized fluorophores: wg refractive-index dependence
0
0.5
1
1.5
2
2.5
3
0 5 10 15 20
Sp
on
tan
eo
us
em
iss
ion
rate
sum of all modes
bound modes
1.50
1.56
1.80
2.30
cover (nc = 1.33)
waveguide (nwg, h)
substrate (ns = 1.46)
2 22 wg s
hV n n
1.50 1.56
1.80
2.30
17X
Dipole angular orientation:
cover (nc = 1.33)
waveguide (1.56, h)
substrate (ns = 1.46)
0.0
0.5
1.0
1.5
2.0
2.5
0 0.2 0.4 0.6 0.8 1
0
0.5
1
1.5
2
2.5
0 0.2 0.4 0.6 0.8 1
222 swg nnh
V
2
2z
r =
2 E
z2/(
Ex2 +
Ey2
)
Spo
ntan
eou
s em
issi
on r
ate
V = 1.03
V = 1.53
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 2 4 6 8 10
sum of all modes
bound modes
substrate modes
cover-substrate modes
V = 1.03
V = 1.53
Preview of my Wednesday’s talk
Following Charge-Transfer Processes with Integrated Photonic Devices
Sergio B. Mendes Dept. of Physics and Astronomy
University of Louisville - USA
36 UFRGS - July 15, 2015
NSF, NIH, NASA, KSEF
Acknowledgments:
• Prof. Marty O’Toole • Prof. Bruce Alphenaar • Prof. Cindy Harnett • Prof. Mike Behrenfeld • Prof. S. Scott Saavedra • Prof. Neal R. Armstrong • Prof. Roberto Guzman • Dr. Basil Swanson • Dr. Karen Grace • Prof. Geoff Hoops
• Xue Han (PhD student) • Scott Smith (PhD student) • Jafar Ghithan (Ph.D. student) • Uliana Salgaeva (Ph.D. student, Perm University) • Amna Zojl • Brent Mode • Conrad Smart
Senior Collaborators
Current Students
Financial Support:
• Dr. Rodrigo Wiederkehr (post-doc) • Dr. Mustafa Aslan (post-doc) • Prof. Marcelo B. Pereira (post-doc) • Dr. Brooke Beam (Ph.D.) • Dr. John T. Bradshaw (Ph.D.) • Dr. Anne Runge (Ph.D.) • Dr. Lirong Wang (Ph.D.) • Dr. Emre Araci (Ph.D.) • Sergey Mushinsky (exchange student) • Aleksey Sosunov (exchange student) • Dr. Roman Ponomarev (exchange student) • Boris Anokhin (exchange student) • Donna Orem (MS) • Jennifer Burnett (MS) • Collin Hayes (undergr) • Nathan Webster (undergr) • Courtney Byard (undergr) • Rion Shuppe (undergr) • Paul Davis (undergr) • Daniel Frayer (M.S.) • Jill Craven (undergrad) • Jinuk Jang (undergrad) • Nick Cooper (undergr) • Jason Payne (undergr)
Former Students and Post-Docs