t1 tutorial description - iaria.org · ii work area: essays for optical communications schematic...
TRANSCRIPT
T1 Tutorial description
This tutorial, entitled :
”Visible light communications in smart road infrastructures”,
reports four work areas: Admission Regulation of Traffic to Improve Public
Transport in Urban Areas
Essays for optical communications
Indoor positioning using a-SiCH technology
Connected cars: road to vehicle communication through visible light
II Work Area:
Essays for optical communications
Schematic diagram of the transducers essays. An indoor, line-of-sight visible light communication link.
Optoelectronic WDM system:
Motivation and Objectives
RESEARCH QUESTION : “Which kind of amorphous Si/SiC transducers, should be developed to allow the recovery of specific wavelengths for the transmission over WDM networks, in the visible spectrum, that could compete with conventional detection electronic devices in optical communications industry ?”
System Architecture
Experimental Design
Optoelectronic Algorithm Interface
Applications
MAIN WORK AREAS:
Outline
• Dynamical effects: A two stage active circuit. Optoelectronic simulator.
• Reconfigurable active filters: Opto-electronic conversion. Optoelectronic logic
functions.
• Bias controlled device: Voltage and Optical bias. Self amplification.
Photonic filters.
• Conclusions and future trends.
400 500 600 700 800
0,0
0,1
0,2
0,3
0,4
75 Hz
NC12p-i(a-SiC:H)-n/ITO/p-i(a-Si:H)-n
Ph
oto
cu
rre
nt
(a
)
Wavelength (nm)
-10 V
-5 V
0 V
+3 V
• State of art: Experimental Design Work Area. The original idea.
p-i-n p-i-n
State of art of a-Si/SiC Photodiodes
400 450 500 550 600 650 700 750 8000,00
0,02
0,04
0,06
0,08
0,10
0,12
0,14
0,16
0,18
0,20
#M007192 (2mWcm-2)
#M007192(L=0)
#M006301(L=0)
#M006291(2mWcm-2)
#M006301(2mWcm-2)
#M006291(L=0)
Sen
siti
vit
y (
A/W
)
Wavelength (nm)
Light-to-dark Sensitivity depends strongly on the carbon concentration
-6 -5 -4 -3 -2 -1 0 1 2
-8x10-8
-6x10-8
-4x10-8
-2x10-8
0
a)
S=650 nm
NC#5 (pin/pin)
whithout
optical bias
L=550 nm
L=650 nm
L=450 nm
Photo
curr
ent (A
)
Voltage (V)Green Blue
Color rejections function on the applied bias
P. Louro, M. Fernandes, A. Fantoni, G. Lavareda, C. Nunes de Carvalho, R. Schwarz and M. Vieira “An amorphous SiC/Si image photodetector with voltage-selectable spectral response”Thin Solid Films, 511-512, 2006, pp.167-171
The thickness of the front photodiode was optimized for blue collection and red transmittance The thickness of the back photodiode was adjusted to achieve high collection in the red spectral range
Produced by PECVD
400 500 600 700 800
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35Front cell
ITO/pi´(a-SiC:H)n/ITO/pi(a-Si:H)n/ITO
Pho
tocurr
ent (
a)
Wavelength (nm)
0.0
0.5
1.0
1.5
2.0-5V
+1V
Voltage controlled optical filter
Front diode –Cuts the red
Back diode –Cuts the blue Back cell
400 500 600 700 800
0.0
0.1
0.2
0.3 NC10 p-i'(a-SiC:H)-n-p-i(a-Si:H)-n
75 Hz
Ph
oto
cu
rre
nt (
A)
Wavelength (nm)
-10 V
-5 V
0 V
+3 V
M. Vieira, P. Louro, M. Fernandes, M.A. Vieira, A. Fantoni and M. Barata, “Large area a-SiC:H WDM devices for signal multiplexing and demultiplexing in the visible spectrum”, Thin Solid Films 517 (2009), pp. 6435-6439. Voltage controlled spectral response.
Both front and back diodes act as optical filters confining, respectively, the blue and the red optical carriers, while the green ones are absorbed across both.
0.0 1.0 2.0 3.0 4.0 5.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
V=+1V
V=-8V
G
BR
B (-8V)
R(-8V)
G(-8)
B(+1)
R(+1)
G(+1)
Led R
Led G
Led B
Ph
oto
cu
rre
nt
(A
)
Time (ms)
Front
diode
Back
diode
-
Substrate InOx
p (a-SiC:H)
n (a-SiC:H)
i (a-SiC:H)
200 nm
p (a-SiC:H)
i (a-Si:H)
1000 nm
n (a-SiC:H)
n (a-SiC:H) InOx
B R G
B
R
G
V
Wavelength
Division
Multiplexing
Wavelength
Division
Demultiplexing
Operation Principle
R+G+B R&G&B
soma
+1V
-8V
###
###
###
###
###
###
###
###
###
Experimental Design Work Area
M. Vieira, M. Fernandes, P. Louro, A. Fantoni, M. Barata, M A Vieira, “Multilayered a-SiC:H device for Wavelength-Division (de)Multiplexing applications in the visible spectrum” Mater. Res. Soc. Symp. Proc. Volume 1066 (2008), pp.225-230 DOI:10.1557/PROC-1066-A08-01
Optical
bias
Optical
bias
GL
AS
S
200 nm(a-SiC:H)
Applied Voltage
Channels
B
TC
O
i
1000 nm
(a-Si:H)
p pn n
TC
O
Front diode Back diode
Gi’
G
Optical bias controlled optical filter
400 450 500 550 600 650 7000
20
40
60
80
100
120
140N
orm
aliz
ed
Ph
oto
cu
rre
nt
No background
Red background
Green background
Blue background
Violet background
V=-8V
500 Hz
Ph
oto
cu
rre
nt (n
A)
Wavelength (nm)
N3500
R3500
G3500
B3500
Violtet 3500
0
1
p-i'-n diode
p-i-n diode
B
C
400 450 500 550 600 650 7000
5
10
15
20
25
30
35
40
45
50Back optical bias
No
rma
lize
d P
ho
tocu
rre
nt
V=-8V
500 Hz
Ph
oto
cu
rre
nt
(nA
)
Wavelength (nm)
no bias 500 Hz
R10mA
G10mA
B10mA
V10mA
0
1
2
p-i'-n diodep-i-n diode
B
C
Op
tical b
ias O
ptical b
ias
Dynamics of electrical model with light biasing control
ac equivalent circuit
Two optical gate connections
Q1
Q2 i
n
n
p
i
n
n
p
i
n
n
p
i
n
n
p
i
n
n
p
i
n
n
p
i
n
n
p
i
n
n
p
p
i
n
p
p
i
n
p
p
i
n
p
p
i ’
n
p
p
i
n
p
p
i
n
p
p
i
n
p
p
i
n
p
p
i ’
n
p
I1
I2
I3
I4
M A Vieira, M. Vieira, M. Fernandes, A. Fantoni, P. Louro, M. Barata, Amorphous and Polycrystalline Thin-Film Silicon Science and Technology — 2009, MRS Proceedings Volume 1153, A08-03
Two amplifying elements Two capacitive filter sections
Charge storage modelled by space-charge layer
Two stage active circuit
Light Biasing Control
Electrically programmable
Light triggering
State-space realization of the photonics active filters
State-space
realization of the
equivalent circuit
B
A
C dt
State variables
System matrix
Control matrix Output matrix
Output variables i1,2 Input variables
V1,2
+ +
i
V 1,2
How does the system input affect the state change??
How does the current state affect the state change??
tvR
ti 2,1
2
10
Dyn
am
ics
of
a p
ara
llel b
ucket
co
nn
ec
tio
n
)()(111
11
2,1
2
2
1
1
2,1
222121
11112,1ti
C
Ctv
CRCRCR
CRCR
dt
dv
M. A. Vieira, M. Vieira, J. Costa, P. Louro, M. Fernandes, A. Fantoni, ”Double pin Photodiodes with two Optical Gate Connections for Light Triggering: A capacitive two-phototransistor model” in Sensors & Transducers Journal Vol. 10, Special Issue, February 2011, pp.96-120.
.
/C1
/C2
/R1C1
/R2
dt
/R1C2
/R1C1
dt
/R1C2-1/R2C2
i(t)
+
i2(t)
i1(t) ++
++
+
v1
.
.v2
+
v1
v2
/C1
/C2
/R1C1
/R2
dt dt
/R1C2
/R1C1
dt dt
/R1C2-1/R2C2
i(t)
+
i2(t)
i1(t) ++
++
+
v1
.
.v2
+
v1
v2
Simulator Electrical model Dynamics of electrical model
with light biasing control
Input channels (R G B) Background (R G B) Multiplexed signal
Optoelecronic simulator Vieira, M.A., Louro, P., Vieira, M., Fantoni, A., Steiger-Garção, A. “Light-activated amplification in Si-C tandem devices: A capacitive active filter model “ IEEE SENSORS JOURNAL, VOL. 12, NO. 6, JUNE 2012 pp. 1755-1762 DOI: 10.1109/JSEN.2011.21765372012
Validation of the model
.
Under negative dc
Good agreement between experimental and simulated data
experimental (solid lines)
simulated (symbols)
Without background Encoding: 8-levels
MATLAB as a programming environment and the four order Runge-Kutta
method to solve the state equations
0,0 1,0 2,00
5
10
15
20
25
R
R=0.19
R
B=1.70
R
G=0.42
Red background no background)
IR
IB
IGpi´n
IGpin
IR
IGR
IGB
IB
Ion
I -8V
Ph
oto
cu
rre
nt
(A
)
Time (ms)
0,000 0,001 0,002
0,0
5,0x10-6
1,0x10-5
1,5x10-5
2,0x10-5
2,5x10-5
###
###
=0
=624 nm
###
###
###
###
###
###
0,000 0,001 0,002
B
C
M A Vieira, M. Vieira, M. Fernandes, A. Fantoni, P. Louro, M. Barata, Amorphous and Polycrystalline Thin-Film Silicon Science and Technology — 2009, MRS Proceedings Volume 1153, A08-03
Front Red background Encoding: 4-levels
0,00 0,25 0,50 0,75 1,00 1,250
5
10
15
20=0=624 nm
Photo
curr
ent (
A)
Time (ms)
Rdark
Gdark
Bdark
Red
blue
green
Optical encoded data stream front red/without irradiation
13
0,0 0,5 1,0 1,5 2,0 2,50
10
20
30
40
000
..... tn=n
...........t8=Tt
0=t
R
6000bps
Ph
oto
cu
rren
t (
A)
Time (ms)
D
R
G
B
###
###
###
###
###
###
###
_GB
_G0
_0B
_00
_GB
_0B
_G0
_00
RGB 0GB
R0B 00B
RG0 0G0 R00 000
F
Red Background :
The output waveform becomes a
main 4-level encoding (22).
Without optical bias is an 8-level encoding (23)
to which it corresponds 8 different photocurrent
thresholds.
(αRR<<1)
(αRB>>1)
(αRG<1)
_G0
_0B
_GB
_00
SiC tuneable background nonlinearity-based RGB logic gates
Optical encoded data stream front/back violet irradiation
14
Back violet optical bias :
The output waveform
becomes a main 4-level
encoding (22).
Front violet optical bias
8-level encoding (23) to which it
corresponds 8 different
photocurrent thresholds.
(αVR>>1)
(αVB~1)
(αVG>1)
0,0 0,5 1,0 1,5 2,0 2,50
1
2
3
4
5 Red
Green
Blue
Vpin1
Vpin2
###
###
###
###
pin2
pin1
Photo
curr
ent (a
.u)
Time (ms)
R
R
R
R
0
0
0
0
B B B B
0 0 0 0
0
0
0
0
B
B
B
B
(αVR<<1)
(αVB>>1)
(αVG~1)
G
G
G
G
0
0
0
0
0,0 0,5 1,0 1,5 2,0 2,50,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
V
B pin1
V
B pin2
V
pin2
V
pin1
V
pin2
V
R pin1
Violet background
V
R,G
,B
Time (ms)
10 point AA Smoothing of Data3_B
10 point AA Smoothing of Data3_E
15 point AA Smoothing of Data3_I
15 point AA Smoothing of Data3_C
15 point AA Smoothing of Data3_G
15 point AA Smoothing of Data3_J
SiC tuneable background nonlinearity-based RGB logic gates
Optoelectronic model
Op
tica
l b
ias
Op
tica
l b
ias GL
AS
S
200 nm
(a-SiC:H)
Applied Voltage
Channels
B
TC
O
i
1000 nm
(a-Si:H)
p p n n TC
O
Front diode Back diode
G i’
R
i´ p
n p
n n
i p
Q1
Q2
IB,IG
IR,IG
400 500 600 700 800
0.0
0.1
0.2
0.3 NC10 p-i'(a-SiC:H)-n-p-i(a-Si:H)-n
75 Hz
Ph
oto
cu
rre
nt (
A)
Wavelength (nm)
-10 V
-5 V
0 V
+3 V
400 450 500 550 600 650 7000
1
2
3
4
5
6
7
8 624nm, 3500Hz
624nm, 250Hz
526nm, 3500Hz
526nm, 250Hz
470nm, 3500Hz
470nm, 250Hz
400nm, 3500Hz
400nm, 250Hz
Gain
(
R,
G,
B)
Wavelength (nm)
R3500Hz
R250Hz
G3500Hz
G250Hz
B35000Hz
B250Hz
V250
V3500
Light-activated pi’n/pin a-SiC:H devices that combines the demultiplexing operation with the simultaneous photodetection and self amplification of an optical signal were designed, analyzed, validated and evaluated.
Depending on the applied voltage and wavelength of the external background it acts either as a short- or a long- pass band filter or as a band-stop filter.
Conclusions
Experimental Design
tvR
ti 2,1
2
10
)()(111
11
2,1
2
2
1
1
2,1
222121
11112,1ti
C
Ctv
CRCRCR
CRCR
dt
dv