Visible Light Communication based on Chaos Encryption Scheme

HUDA KADHIM RUMUH, IBRAHIM ABDULLAH MARDAS

College of Engineering, Electrical Engineering,

Babylon University,

Babylon,

IRAQ

Abstract: -To accommodate extremely high levels of data traffic, today's communications networks are

signal's transmission via the optical fiber medium by our suggested method, which makes use of the double

delay feedback technique to create the optical chaotic signal. The additive chaos masking system is utilized to

execute the mixing of incoming signals with chaos. This method demonstrates several valuable qualities,

including simplicity and the ease with which a message may be recovered. To explore the propagation concerns

that are related to secure signal transmission, chaotic data, which is a combination of incoming signals and

random noise, is transmitted via the medium of optical fiber. To properly regulate the linear impairments of

optical fiber, which is required for the efficient transmission of a secure signal, the plan is put into action for

long-haul communication to facilitate the long-distance transfer of data. Adjustments are made to the

parameters on both the transmitting and receiving ends to achieve synchronization between the two processes.

This is done in such a way that the received signal may be restored to its original state by subtracting the

Received: April 22, 2023. Revised: February 15, 2024. Accepted: March 15, 2023. Published: May 27, 2024.

1 Introduction

This study presents the method for secured

communication in Optisystem software by making

use of a chaotic laser. Spread spectrum signals are

used in chaotic communication; these signals make

use of a vast bandwidth and have a low power

employed, [3]. The Q-factor is the minimum optical

signal-to-noise ratio required to achieve a specific

bit error rate. Optical fiber cable is currently the

suggested choice for data transfer, with less noise

interference, and a longer transmission range

because of its high bandwidth. Furthermore, because

comprise wireless communication technologies

including free space optics (FSO) and optical

wireless communications (OWC) as well as optical

fiber communication, [8], [9]. One of the types is

communication through optical fiber. There are

three different ways to hide messages inside the

chaos of an optical communication system: Additive

chaos masking (ACM), also known as chaos

modulation (CM), or chaos shift keying (CSK),

[10]. [ACM] stands for additive chaos masking;

recover messages, and its implementation in

Optisystem software version 14.0, [11]. In Figure 1,

which depicts our suggested security

implementation via the ACM method, as you can

see, both the transmitting and receiving sides are

equipped with two chaotic systems that are rather

comparable to one another. The first data signal,

represented by d(t), is covered up by the chaotic

signal, denoted by c(t), which is produced at the

transmitting end using the double delay feedback

chaotic laser, [12]. To generate chaos with the

characteristics that are wanted, the settings of the

current source and the semiconductor laser are

altered. This signal (s(t)) serves as noise for

potential intruders and conceals the original data

(d(t)) in its transmissions, [13]. The signal, denoted

by s(t), is then sent across the channel and is

followed by the subtraction of another chaotic

signal, denoted by c(t), which is analogous to s(t)

but is instead produced by a second chaotic

two chaotic lasers need to have identical properties,

but synchronization between them is also an

essential goal to work toward. It just takes a very

security. Their research report focuses on the

implementation of a Radio-over-Fiber (RoF)

network in the context of 5G front haul. The three

most widely used approaches are CSK, CM, and

CMS. CMS is the most cost-effective and user-

friendly option. The initial phase of the study

confirms the security of the RoF signal by

employing optical time domain and spectrum graphs

with the use of optical time domain visualizers and

well up to 15 km of fiber length with 10 Gbps data

throughput and security features. By boosting laser

power to 20 dBm, BER decreases considerably.

However, linear impairment control is essential for

optimal RoF signal quality.

In 2023, [18], they demonstrated Optisystem

7.0's chaos-based secure fiber-optic communication

system. Standard single-mode fiber transmits a 10

Gb/s externally modulated signal across 100

kilometers. Changing semiconductor laser rate

transmission distance to 104 km (80%). Data was

retrieved at the receiver with a maximum Q-factor

of 4.2 and a minimum bit error rate of.

In 2023, [19], an optical chaotic system was

created and tested using OptiSystem software to

evaluate its performance under different weather

situations. The system is a secure hybrid

combination of free space and fiber optic (FSO/FO)

technology. The chaotic signal conceals the message

within this highly secure communication

enhances the link distance by a significant margin of

37-40%.

are couplers; OC2 Light divides the MZM output

into two; and finally, the RF and PD driver leads to

the MZM optoelectronic reflection feedback. From

the EDFA to the MZM optical feedback, the laser

output is chaotic and has the power of Pout thanks

to the MZM, [22].

Equation (1) represents the output property of

the nonlinear device MZM of the OEO chaotic

system with double delay feedback:

The coupler produces two beams of light, each of

which is equally strong, but only one of these is

amplified by EDFA. After that, it is linked with the

static fixed power laser that is generated by the

continuous laser, and it is then entered into the

MZM for a second time to carry out non-linear

modulation and make chaotic lasers. The second one

goes from the feedback arm (MZM) into the

photodetector (PD) to transform an optical signal

into an electrical signal. The photodetector is

been conducted to investigate the effects of MZM

bias voltage on the chaotic behavior of OEFB. The

output of the optoelectronic oscillator is sent back to

the MZM over a delayed optical channel. This

causes the gain coefficient of the original OEO to be

dynamically altered, and it also adds an extra time

delay to the system, which causes it to produce a

more complicated and chaotic laser signal. The

aforementioned features help construct a chaotic

secure communication system that offers a better

that is mean, chaotic behavior increased and the

opposite happens with modulation peak current.

Table 1. Semiconductor laser Parameter of Chaotic

Signal

500 THz. Figure 7 illustrates a time domain signal

that the invaders are unable to comprehend in any

way. A person who does not have the appropriate

information and understanding of the created

chaotic signal is unable to recognize the original

message signal that was transmitted from the

transmitting end, as seen in Figure 7. This can be

seen quite clearly in Figure 8. This ensured that our

signal would not be intercepted by unauthorized

parties and offered an adequate level of protection

Fig. 7: Input message embedded in chaos

adding and after the subtraction of chaos to the

signal. To reiterate, the intruder is unable to

decipher the real information in the frequency

domain.

At the receiving end, the chaotic signal that was

found to have been contaminated with the official

signal was removed from the similar chaos that had

been generated by the second semiconductor laser.

The signal was picked up by the photodiode, which

then transformed it into a signal that was analogous

for long-distance transmission. We found that when

the fiber lengths increased, the Q-factor dropped by

a significant amount.

and attenuation is required in order to carry out

simulations. The results are displayed in Figure 10,

which demonstrates that the system functions well

up to a channel length of 4 km. After that, an

exponential increase in bit error rate is detected,

which suggests that it is feasible to recover the

signal that was originally broadcast, although with

errors. Since the suggested system is optimized for

10 Gbps, it can function satisfactorily up to a fiber

length of 4 km because of this. An increase in the

Table 2. RESULT of the simulation of Proposed

double delay feedback with data rate (10Gbps)

The results of a comparison of the bit error rate

and the Q-factor for various fiber lengths are

presented in Table 2. After researching the bit error

rate as well as the Q factor for fibers of varying

lengths, the researchers concluded that the bit error

rate was growing with the rising fiber lengths. On

the other hand, the Q-factor decreased when the

length of the fiber was increased. This nonlinear

[4] C. Zhang, W. Zhang, X. He, C. Chen, H.

[5] T. Wu, C. Zhang, C. Chen, H. Hou, H. Wei,

[7] CH. Cheng, CY. Chen, JD. Chen, DK. Pan,

[8] CY Chen, CH Cheng, DK Pan, FY Lin.,

[10] M. Preishuber, T. Hütter, S. Katzenbeisser