Bit Error Rate Performance for Optical Fiber System

Communication implies transmit of information from one point to another, When it is necessary to transfer information, like image, speech, or data, over a distance. The concept is to use carrier wave communication [1]. Fiber optics have become a huge building blocks in the telecommunication field and it’s the best system for transmitting information, since its invention in the early 1970s, the need and use of optical fiber have grown extremely [2,3]. Optical Fibers are made of ultra-pure glass or Plastic that can transfer light from one point to another without much loss or attenuation [4]. Because of evolution, studies shown that optical communication systems in the future will become stronger and better than current systems [5].

I<ID for bit 1 because of receiver fuss. An error also Occurs if I>ID for bit 0. Both sources of errors can be included by defining the error probability as BER=P (1) Common to assume Gaussian static for the current P(0/1)=area below the decision level ID Where Q is Quality factor And the equations that describe the behavior of it are: E out (t)=E in (t).Cos (Δ (t)).exp(j. Δ ∅ (t)) Where Δ is a phase difference between two branches and refer to: With ER 1 . Arc tan 4 1 extrat And Δ∅ is the signal phase change defined as Where, the parameter SC is -1 if negative signal chirp is true or 1 if negative signal chirp is false. Extract is the extinction ratio, SF is the symmetry factor, and modulation (t) is the electrical input signal. The incoming signal is confined between 0 and 1. For parameterized and noise bins signals, the average power is calculated according to the above [6].

Computer Modeling
Computer modeled for receiver sensitivity (

Simulation Parameter
Simulation parameters are shown in Table 1.

Simulation OPTI system
OPTI system is an innovative optical communication system simulation package for design, testing, and optimization of virtually any type of optical link in the physical layer of a board spectrum of optical networks [14-17].
OPTI system is a standalone product that does not rely on other simulation frameworks, it is physical layer simulator based on the realistic modeling of fiber-optic communication systems, it possesses a new powerful simulation environment and a truly hierarchical definition of components and systems, Its capabilities can be extended easily by addition of user components, also can be seamlessly interfaced to a wide range of tools [18,19].
The extensive library of active and passive components includes realistic wavelength dependent parameters. Parameter sweeps and its optimizations allow you to investigate the effect of particular device specifications on system performance, created to address the needs of system integrators, optical telecom engineers, research scientists, and academia. OPTI System satisfies the demand of the booming photonics  market and facilitates the use of optical system tools. We can simulate implemented scenario by using OPTI system program as shown in  In this step of project we adjusted value of attenuator until to reach optimum values of BER (10 -9 ), Q factor 6 after adjustable it was found that, the minimum optical power that the receiver need to operate reliable (PIN).
In this step of the project, it's important to find the values of optimum power for both source and detectors to find the perfect length by using unipolar, bipolar signal format and the most uses wave lengths (1550 nm, 1310 nm). This can be done by setting the value of BER to (10 -9 ) and Q factor to 6.
Then if value of optical attenuator is gradually tuned, the values of both BER and Q factor will vary respectively until finding the considered values of the performance parameter.

Result and Discussions
After execution of simulation for adjustable value of attenuation and length we get the following results in term of table and graph and are plotted by using MATLAB program.

Receiver sensitivity result
Variation of power vs. Q factor and BER for PIN is shown in Table 2.
Variation of power vs. Q factor and BER for APD is shown in Table 3.
It's clear that modulation technique is being used to modulate signal and using PIN detection to convert light signal to electrical signal that to evaluate the performance of optical through bit error rate, BER in dB (Figure 6). There are many factors effect on BER such as Q factor, if Q factor increase the BER will decrease (Figure 7). BER against attenuation, when the probability of error increases, the attenuation will increase by using PIN detection (Figure 8).
Power against attenuation is the inverse relationship, when the          power decrease the attenuation will increase by using PIN detection (Figure 9). Q Factor against attenuation, when the Q factor increases the attenuation will decrease by using PIN detection ( Figure 10).
We notice that, modulation technique is being used to modulate signal by using APD detection to evaluate the performance of optical through bit error rate BER in dB; there are many factors effect on BER such as Q factor, also its inverse relationship ( Figure 11). Q Factor against attenuation, when the Q factor decreases the attenuation will increase by using APD detection (Figure 12).     Power against attenuation is the inverse relationship, when the power increase the attenuation will decrease by using APD detection (Figure 13).
BER against attenuation, when the probability of error increases, the attenuation will increase by using APD detection.

Power budget result
Variation of power Vs. Q factor and BER for RZ at 1550 nm is shown in Table 4.
Variation of power Vs. Q factor and BER for NRZ at 1550 nm is shown in Table 5.
Variation of power Vs. Q factor and BER for RZ at 1310 nm is shown in Table 6.
Variation of power Vs. Q factor and BER for NRZ at 1310 nm is shown in Table 7.
Eye diagram for 1550 nm with attenuation and (RZ) format is shown in Figures 14-19

Conclusion
Study, analysis, plane and design to simulate bit error rate for optical fiber communication have been done, the objective is achieved by using (OPTI system) and MATLAB software program. Results were obtained in terms of tables and charts.
The parameters which were taken into consideration of the simulation are network, type of coding, optical fiber length, attenuation, wave length, data rate, power detection, type of noise and type of modulator.
From the analysis it was observed that, the power that can operate PIN receiver optimum is 35 and for APD 38.2. Also from the results it's found that APD, receiver is more sensitive than PIN detector which deals with theoretical concepts.
Depending on the previous points, 1550 nm wave length better because it have less attenuation than 1310 nm and the NRZ signaling format it gives the great distance than using RZ signaling format.