COL 11(4), 041901(2013) CHINESE OPTICS LETTERS April 10, 2013
Data signal processing via manchester coding-decoding
method using chaotic signals generated
by PANDA ring resonator
I. S. Amiri
∗
and J. Ali
Institute of Advanced Photonics Science, Nanotechnology Research Alliance,
Universiti Teknologi Malaysia (UTM), 81310 Johor Bahru, Malaysia
∗
Corresponding author: isafiz@yahoo.com
Received October 31, 2012; accepted November 16, 2012; posted online March 8, 2013
We investigate the nonlinear behaviors of light recognized as chaos during the propagation of Gaussian
laser beam inside a nonlinear polarization maintaining and absorption reducing (PANDA) ring resonator
system. It aims to generate the nonlinear behavior of light to obtain data in binary logic codes for
transmission in fiber optics communication. Effective parameters, such as refractive indices of a silicon
waveguide, coupling coefficients (κ), and ring radius ring (R), can be properly selected to operate the
nonlinear behavior. Therefore, the binary coded data generated by the PANDA ring resonator system
can be decoded and converted to Manchester codes, where the decoding process of the transmitted codes
occurs at the end of the transmission link. The simulation results show that the original codes can be
recovered with a high security of signal transmission using the Manchester method.
OCIS codes: 190.0190, 060.0060, 260.0260.
doi: 10.3788/COL201311.041901.
Chaotic signals have attracted interest in the areas of
nonlinear science, communication technology, a nd signal
processing because of their broadband spectrum, as well
as orthogonality and complexity pro perties
[1]
. The po s-
sibility of employing chaotic signals to carry information
was first s tudied in 1993
[2]
. The interest in chaotic com-
munications is due to the favorable properties of chaotic
signals in the fields of security systems or broadband
multiple access systems
[3]
. The nonlinear behavior of
light inside a microring resonator (MRR) occurs when a
strong pulse of light is inserted into the ring system
[4,5]
.
Chaotic controls have been used in a great number of
optical
[6−9]
, engineering
[10,11]
, and biological
[12,13]
design
systems. The theoretical studies of such systems have the
same conceptions as those in ring cavities
[14−16]
and the
Fabry–Perot system
[17−20]
.
Another technique
[21]
used for generating the nonlin-
ear behavior of light in a MRR is through the produc-
tion of secured codes. The generated binary codes can be
encoded and decoded via the Manchester technique
[22]
.
This method is a bi-phase signal-encoding scheme, in
which the direction of the mid-interval transition in-
dicates a value (1 or 0) and provides the clocking
[23]
.
Manchester encoding is a synchronous clock encoding
technique, wherein the ac tua l binary da ta to be trans-
mitted over the cable are not sent as a sequence of logic
1’s and 0’s
[24]
, rather, translated into a slightly different
format that has a number of advantages over straight bi-
nary encoding. Thus, logic 0 is indicated by a 0 to 1
(upward transition at bit center) transition at the center
of the bit, whereas lo gic 1 is indicated by a 1 to 0 (down-
ward trans itio n at bit center) transition at the c enter of
the bit (Halsall, 1995).
The Manchester code is used in binary search
algorithms
[25]
to determine the location of the collision
bits. In the Manchester encoding method, the negative
edge of the signal means data-1, whereas the positive
edge o f the signal means data-0. In the decoding method,
the signals are unchanged if collision occurs. Thus, the
reader can easily find the unchanged signals to identify
the collis ion and determine where the collision bits are.
In this letter, the generation of chaotic signals in a polar-
ization maintaining and absorption reducing (PANDA)
ring resonator is presented. The chaotic signal output
can be easily c ontrolled because of the interferometric
role of this system. This study involves two prop erties
of light, i.e., the chaos behavior of the PANDA ring res-
onator system was used to generate the demanded binary
codes, a suitable technique for encoding and decoding the
transmitted information via o ptica l binary signals. The
transmitting signals can be secured throughout the prop-
agation dur ing fiber optics communication, whereby the
original and initial s ignals are recovered using the Manch-
ester technique.
The proposed system of chaotic signal generation,
known as the PANDA ring resonator (Fig. 1), comprises
a centered ring resonator matched to two smaller ring
resonators o n the right and left sides. This s ystem also
has two straight waveguides on the top and bottom sides,
where two input signals can be introduced into the s ys-
tem via the input and a dd ports.
The Kerr effect caus e s variations in the refractive index
(n) of the medium and is g iven by
[26]
n = n
0
+ n
2
I = n
0
+
n
2
A
eff
P, (1)
where n
0
and n
2
are the linear and nonlinea r refractive
indexes, r e spectively. I and P are the optical intensity
and power, respe ctively. The effective mode core area
of the device (A
eff
)
[27]
ranges from 0.50 to 0.10 µm
2[28]
.
The input optical fields of the Gaussian pulses are given
by
[29]
E
i1
(t) = E
i2
(t) = E
0
exp
z
2L
D
− iω
0
t
, (2)
1671-7694/2013/041901(4) 041901-1
c
2013 Chinese Optics Letters