International Journal of Engineering Trends and Technology (IJETT) – Volume 10 Number 5 - Apr 2014
Design of 1x3 Optoelectronic Switch Based on MZI Structure
Chetan B. Bambhroliya#1, Rahul J. Thumar*2, Prof. Sarman K. Hadia#3
#
Communication System Engineering, Charusat University
At & Po: Changa-388421, Dist-Anand, India
* Assistant Professor,
Dr. Subhash Technical Campus, At: Junagadh-362001, Gujarat, India
* Associate Professor,
Communication System Engineering, Charusat University
At & Po: Changa-388421, Dist-Anand, India
Abstract— we present an electro-optic 1x3 switching
device based on Integrated Mach-Zehnder interferometer
made by Titanium diffusion in Lithium Niobate substrate.
The switching between the ports is achieved by an electrooptic effect within such structure. Voltage, applied to the
electrodes deposited on the integrated Mach-Zehnder
interferometer, creates an electric field distribution within
the substrate, which consequently changes its refractive
index. If properly designed, the induced change in the
refractive index leads to different coupling between
individual ports.
Keywords—
Mach-Zehnder interferometer, Electro
optics, Directional couplers, Switching voltage, All optical
switch.
I. INTRODUCTION
Directional couplers consisting of two closely coupled
waveguide are simple and essential elements in optical
systems. In a modern communication network, switches are
most important part of a network and in optical
communication a switching in all light, means in optical
domain is more important than switching in electrical domain
i.e. conversion from optical to electrical and electrical to
optical. With such a conversion the data transfer capability
and speed of switching reliability is less. The speed of optical
switches is necessarily has to match with currently new
generation photonic devices in which light is not only carry
information but also control the switching path is much
important. The electro-optic effect is a change in optical
properties of a material in response to electrical field that
various slowly with compared to frequency of light. One of
the key elements that have many applications in optical
wavelength division demultiplexing and routing, are all
optical switches. There are some of works in the field of
optical switching based on directional couplers. In recent
years various materials and configurations have been
employed for the development of optical switches. For
switching operation, some of mechanisms, such as thermoOptic [1] and electro-optic [2, 3] can be used. But in optical
communication, all-optical devices realizing high performance
and speed are preferred. For applying the directional coupler
to all- optical purposes, materials with high nonlinear
characteristics are suitable. All-optical switches are desired
ISSN: 2231-5381
devices in optical telecommunication. They can perform a
variety of applications, particularly in single routing and time
division signal processing. One of the major advantages of alloptical switches is that they avoid the need for optic-electronic
and electronic-optic (o-e-o) conversions [2]. In spite of
mentioned subjects, an electro-optic switch based on
integrated Mach-Zehnder interferometer is required in many
optical switching systems. To the best of our Knowledge,
there is not any proposal for an electro-optic 3x3 switch based
on integrated Mach-Zehnder interferometer that can work as
switch. The proposed switch can have many interesting
applications in optical telecommunication. Titanium diffused
lithium niobate or the Ti:LiNbO3 waveguide is used as the
waveguide medium in the optical switch design. The reason
that of chosen this material is it has very low loss and
switching voltage need to applied is small which is normally
below 8V. In this work, we designed and simulated a new an
electro-optic 1x3 switch based on integrated Mach- Zehnder
interferometer. The device works based on electro-optic
effects refer to changes in the refractive index of material
induced by the application of an external electric field. The
simulation of the structure is done using OptiBPM software.
In the next section, we will present the design and simulation
results and the paper will continue with conclusion, finally.
II. SWITCH DESIGN
We assume that the integrated switch is produced on a z-cut
wafer Lithium Niobate, and is surrounded by air cladding. The
device is targeted at the Y-axis optical Lithium Niobate.
Therefore, we define a diffused material for the substrate and
a dielectric material for cladding. The dielectric material
chose is air with refractive index air n =1.0. The waveguides
of Mach-Zehnder interferometer are produced by diffusion of
Titanium in Lithium Niobate substrate. Just one diffused
profile is required (TiLiNbO3). All switches device is 33 mm
long and not more than 100 microns wide. The waveguide has
a width of 8.0 µm Ti – diffused profile. The wafer has same
refractive index like that of Lithium Niobate. The 3D wafer
properties include air as a coating material with a thickness of
2.0 µm. It has Lithium Niobate as a substrate with a thickness
of 10 µm. The device was created with the layout designer in
th software optiBPM Optiwave provided as shown in Fig. 1
http://www.ijettjournal.org
Page 260
International Journal of Engineering Trends and Technology (IJETT) – Volume 10 Number 5 - Apr 2014
between the electrodes, the three guides experiences an
applied field E in opposite directions and hence experience
opposite changes in their refractive indices. The
corresponding switching voltage V0 is [5],
V0 
Figure 1 A design of 1x3 optical switch of Mach-Zehnder interferometer
without electrode region
The RI profile of the XY slice was audited The region of the
electrode on the substrate also defined. We have created the
electrodes on a buffer layer. The buffer layer has a thickness
of 0.3 µm and a refractive index of 1.47. It has a horizontal
and vertical permittivity of 4 and the electrode has a thickness
of 4.0 µm. The three regions defined electrode has several
design parameters. First region has a width of 50 µm and a
voltage of 0.0 V. The second electrode region has a width of
26 micrometers and a voltage of 0.0 V. The third electrode
region has a width of 50 micrometers and a voltage of 0.0V.
The gap of 1-2 and 2-3 is equal 6.5. The second electrode has
a central position of 5.3. The input plane has been selected
with MODE like the starting field and 0.0 like Z-offset. After
the input plane defined data set is MODAL refractive index
and wavelength of 1.3 µm comprehensively. The 2D features
have been put in TM polarization. Finite Difference scheme of
engine parameters 0.5, the propagation step of 1.3 and TBC as
a boundary condition. We calculated the isotropic 2D
simulation. We varied the voltage electrodes for the Region
2nd. First the switching voltage of 0.0 V, then 7.0 V was
checked. Further studies electro-optical switches have been
using the scripting language [3]. When we run a simple scan
script, we get a graphic representation of the optical field
overlap in comparison to the number of iterations. It then
became clear that the electro-optic switch is fully switching
the total input signal from one output port to another for the
second electrode voltage from -7.0V to 0.0V & from 0.0V to
7.0V.
Scripting: (using VB script)
ParamMgr.Setparam "V2",-7.0
For x = 1 to NumIterations
ParamMgr.Simulate
ParamMgr.Setparam "V2", 3.2*x
WGMgr.Sleep (50)
Next
A nonlinear directional coupler includes three waveguides that
have a small distance and fully coupling takes place between
them in one coupling length. One of these waveguides or all
have the nonlinear behaviour means, we can change the
refractive index of nonlinear waveguide by applying a voltage
ISSN: 2231-5381
3 d
2 n 3 rL0
Where,
L0 = transfer distance, which is depends on the efficiency
coupling C between each two guides,
d = coupling separation,
n = refractive index of each guide which is equals,
r = the appropriate Pockels coefficient,
V0 depends on the refractive indices and the geometry of the
guides. The coupling efficiency can be controlled by external
voltage level applied through the electrode. The proposed
structure for an electro-optic 1x3 switch based on integrated
Mach-Zehnder interferometer is shown in Fig. 2.
Figure 2 A design of 3x3 electro-optic switch based on Mach-Zehnder
Interferometer
TABLE 1:
Specification of Electrode region and Switching Voltage
Out
put
Port
Electrode-1
Center
Electrode-2 Buffer
Electrode
Layer
W
V
W
V
W
V
W µm
µm
(V)
µm
(V)
µm
(V)
1
10
0
26
0
10
0
0.2
2
10
+7
10
-7
10
0
0.2
3
10
-7
10
+7
10
0
0.2
Inter gap between 1st and
Inter gap between center
center electrode:- 5 (µm)
and 2nd electrode:- 5(µm)
Electrode thickness :- 3(µm)
A switching operation was achieved by properly changing the
range of various parameters and set it as shown in table 1.
http://www.ijettjournal.org
Page 261
International Journal of Engineering Trends and Technology (IJETT) – Volume 10 Number 5 - Apr 2014
III. SIMULATION AND RESULTS
The complete design was stimulated in 2D using beam
propagation method in Opti BPM Cad software. For
simulation we set the global data with refractive index model
and wavelength 1.3 micrometer. The 2D property has set with
TM polarization, beam propagation method solver as a
paraxial, engine with finite difference, scheme parameter 0.5,
propagation step 1.5 and boundary condition TBC.[7]
50
1.01
1.01
0.8
0.8
X cut = 16500
changing the voltage. Mach Zehnder Interferometer can be
used as active optical switch if a voltage is applied.
33000
30000
30
10
0.6
0.6
Z
20000
X
Z
Y
0
-10
0.4
0.4
10000
-30
0.2
0.2
-50
0
1.01
0
10000
20000
30000
0
33000
Y cut = -0.1 50
50
1.01
0.8
30
30
0.8
0.6
10
-50
-10
0
Y
10
30
50
0
0.6
Figure 6 A Powers in Output Wave Guides
0
Y
Z
Z
-30
10
Y
X
-10
0.4
-10
0.4
-30
0.2
0.2
-30
0
-50
0
10000
20000
30000
X
0
-50
10000
20000
X
33000
0
30000
33000
Figure 3 The output power vs. Iterations in each state according to the effect
of changing the voltage 0.0Vstate 0
50
1.01
1.01
0.8
0.8
X cut = 16500
33000
30000
30
0.6
0.6
20000
Z
0
X
Z
Y
10
-10
0.4
0.4
10000
-30
0.2
The simulation results show good performance for this
structure. Table 2 shows the insertion loss, and the extinction
ratio of the proposed optical switch. Insertion loss of a switch
is a part of power that is lost and has to be low for good
performance and the extinction ratio is the ratio of output
power in ON state to output power in OFF state.[5]
P 
Insertion  loss  10log10  out 
 Pin 
[A]
 Pi  Pj 
Crosstalk  10log10 

 Pin 
[B]
0.2
-50
0
0
30000
33000
Y cut = -0.1 50
50
0.8
30
30
0.6
10
0
10000
20000
X
-50
-10
0
Y
10
30
50
0
1.01
0.8
Pi ,Pj = undesired outport
0.6
Z
0
Y
Z
-30
10
Y
1.01
-10
0.4
-10
0.4
TABLE 2
Insertion Loss and Extinction Ratio of the proposed structure
-30
0.2
0.2
-30
0
0
-50
10000
20000
30000
33000
X
0
-50
10000
20000
0
30000
33000
X
Switching State
Figure 4 The output power vs. Iterations in each state according to the effect
of changing the voltage -7.0Vstate 1
50
1.01
1.01
0.8
0.8
X cut = 16500
Case 1
33000
30000
30
0.6
0.6
20000
Case 2
Z
0
X
Z
Y
10
-10
0.4
0.4
10000
-30
0.2
0.2
Case 3
-50
0
1.01
0
30000
33000
Y cut = -0.1 50
50
0.8
30
30
0
10000
20000
X
0.6
-50
-10
0
Y
10
30
50
6.77
9.91
8.76
0.8
0.6
Z
Y
-10
Cross talk (dB)
0
Y
0.4
0
Port 1
Port 2
Port 3
Port 1
Port 2
Port 3
Port 1
Port 2
Port 3
Insertion
Loss.(dB)
0.96
9.20
10.45
15.37
0.45
11.36
13.87
10.36
0.65
1.01
10
10
Z
-30
Out Port
-10
0.4
-30
0.2
0.2
-30
0
0
-50
10000
20000
X
30000
33000
-50
0
10000
20000
X
30000
33000
0
Figure 5 The output power vs. Iterations in each state according to the effect
of changing the voltage 7.0Vstate 2
The applied voltage will determine the amount of optical
power transmitted to a particular output port, and Fig.6 shows
the output power vs. iterations according to the effect of
ISSN: 2231-5381
Figure 7 A power overlap integral at all port of switch.
http://www.ijettjournal.org
Page 262
International Journal of Engineering Trends and Technology (IJETT) – Volume 10 Number 5 - Apr 2014
As the biasing voltage from 0V to increase we can see that
power decrease for port 1 and after 0V biasing voltage light
propagate form port 1 to port 2 and port 3 switching is done.
As the biasing voltage increase form ±3V power decrease and
also coupling efficiency too. So for reliable switching we
chose biasing voltage between ± 7V to ± 7V. The simulation
results show good performance for this structure. The
insertion loss (I.L.) [5] is the important parameter for the
optical switching.
[7]
[8]
[9]
[10]
IV. CONCLUSIONS
The 1×3 Digital optoelectronics switch using mach zehnder
structure has been designed and simulated in Opti-BPM for
light switching to desired port by ± 7V biasing voltage at
1300µm wavelength with TM polarization. Coupling
efficiency of the 1×3 digital optical switch can be controlled
by changing the electrode voltage. When no biasing voltage
applied to electrode the coupling efficiency is almost equal to
100% and when biasing voltage applied the coupling occurs
and by electro-optic effect we switch the light propagation to
desired port. The future proposes work is to design a switch
for high wavelength and independent polarization i.e. both
TM and TE polarization with less losses. With this electrooptic effect, the 1x3 optical switch can act as an electro-optic
switch to switch optical signal to desired output port.
electrode switching voltage”, World Academy of science, Engineering
and Technology 39 2008, 401-407.
Chetan B. Bambhroliya, Rahul J. Thumar, Prof. Sarman K. Hadia 1×2
Digital Optoelectronic Switch using MZI structure and studying the
Effect of Bi-Polar Voltage on Electrode (IJSRD/Vol. 1/Issue
8/2013/0018)
Vandana Sachdeva, Rajeev Ratan, J.S. Mahanwal, “Design of 4×4
banyan optical switch using optoelectronic mzi switches with low
crosstalk,” Indian journal of science and technology,vol.2 No. 10(oct
2009) ISSN:0974-6846,48-51.
Ghanshayam Singh, Tirtha Pratim Bhattacharjee, R.P.Yadav, V.janyani
“Design of non-blocking and rearrangeble modified banyan network
with electro-optic mzi switching elements”. World academy of science,
engineering and technology 43, 2008.
Ghanshayam Singh, R. P. Yadav, V. janyani “performance and
analysis of Ti-LiNbO3 1×2 digital photonic switch with Sio2
layer ”,international conference on Mechanical and Electrical
Technology ,ICMET-2010,122-124
ACKNOWLEDGMENT
I acknowledge the Dr. N. D. Shah principal and Head of
Electronics and communication department, CSPIT, who
helped throughout entire duration work for continuous
encouragement, invaluable help, timely suggestion and
inspired guidance offered, Also Head and principal of DRSTC
to give good platform to done work. Lastly authors express his
sincere thanks to all the friends, family and faculty members
who help directly and indirectly to us.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
D. M. Beggs, T. P. White, L. Cairns, L. O’Faolain, T. F. Krauss,
“Demonstration of an integrated optical switch in a silicon photonic
crystal directional coupler” Physics E, vol. 41 pp. 1111-1114, 2009.
N. Naim, R. Ngah, T. Prakoso, S. Sarnin, H. Abdul Rahman, Z.
Ghassemlooy “Modelling of All-Optical Symmetric Mach- Zehnder
Switch with Asymmetric Coupler”IEEE International RF and
Microwave Con. Pro. December 2-4, 2008.
Ghanshyam Singh, R. P. Yadav, Vijay Janyani, and Aranab
Ray,”Design of 2x2 Optoelectronic Switch Based on MZI and Study
the Effect of Electrode Switching Voltages” World Academy of
Science, Engineering and Technology 39 2008.
Chuan-Tao Zheng, Chun-Sheng Ma, Xin Yan, Xian-Yin Wang, DaMing Zhang, “ Simulation and optimization of polymer directional
coupler electro-optic switch with pushpull electrodes,” Optics
Communications, vol. 281, pp. 3695- 3702, 2008.
Mohammad Syuhaimi , Ab.Rahman , Khaled Mohamed Shaktur,
Rahman Mohammad, “An electro optic 3×3 switch based on integrated
Mach-Zehnder Interferometer”, Proc.8th WSEAS international
conference on applied electromagnetic, wireless and optical
communication, ISBN 978-960-474-167-0,ISSN:1790-2769,11-14.
Ghanshayam shingh, R.P. Yadav, Vijay Jaynyani, and Aranab. “Design
of 2 × 2 Optoelectronics switch based on mzi and studies the effect of
ISSN: 2231-5381
http://www.ijettjournal.org
Page 263