Optical Signal Splitting and Combining Lab Report: Fiber Optics

This report analyzes optical signal splitting and combining within fiber communication systems, focusing on wavelength division multiplexing and demultiplexing. The experiment simulates a real-world fiber communication application, examining signal transmission from the input to the multiplexer, transmission over fiber optic cables, and demultiplexing at the receiver's end. The study includes analysis of splitting and combining at various frequencies, power budget calculations, and observations on fiber optic sensors for measuring physical quantities. The report concludes with recommendations for improving micro bending sensor detection and references relevant research in fiber optic communication.

UNIVERSITY AFFILIATION
DEPARTMENT OR FACULTY
COURSE ID & NAME
TITLE:
OPTICAL SIGNAL SPLITTING AND COMBINING LAB
REPORT
STUDENT NAME
STUDENT REGISTRATION NUMBER
PROFESSOR (TUTOR)
DATE OF SUBMISSION

ABSTRACT
This report seeks to perform a study on the fiber communication system. The areas covered are
with regards to the use of fiber sensors to observe physical quantities in their surroundings. The
report performs a laboratory experiment on the wavelength division multiplexing and
demultiplexing simulating a real-life application of the fiber communication system. The
transmitter end sends the signals from the input to the multiplexer for transmission over one
channel, or fiber optic cable. When the multiplexed signal gets to the receiver’s end, the signal is
demultiplexed and sent out to the respective users. The splitting and combining is analyzed at
different frequencies and the power budget of the system is obtained. The discussion and
research findings cover the experiment as well as the computation of specific parameters.

TABLE OF CONTENTS
ABSTRACT....................................................................................................................................1
LIST OF FIGURES.......................................................................................................................1
INTRODUCTION.........................................................................................................................1
AIMS & OBJECTIVES................................................................................................................3
RESEARCH FINDINGS & OBSERVATIONS..........................................................................4
IMPLEMENTATION....................................................................................................................5
CONCLUSIONS............................................................................................................................5
RECOMMENDATIONS...............................................................................................................5
CONCLUSION..............................................................................................................................5
REFERENCES..............................................................................................................................5
APPENDIX.....................................................................................................................................6
LIST OF FIGURES
Figure 1 Fiber optics communication system-wavelength division multiplexing....................4
LIST OF TABLES
Table 1 Part 1: Digital/TTL -01.................................................................5
Table 2 Part 2: Digital/TTL-02.................................................................5
Table 3 Part 3: Testing for crosstalk............................................................5
INTRODUCTION

Fiber optic communication system are based on the fiber optic cable which provides for
extremely high data rates which allow the very large masses of data to be transmitted at the speed
of light. The fiber optic cable, FOC, transmits data over very long distance. One very common
example is the sea or ocean underground cable that connect continents on the planet earth.
According to the basic model, the bandwidth of the fiber optic communication system
determines the maximum data rate [1]. A FOC link denotes the signal pathway between two
points using the cable. The pathway is the mode or channel that enables transmission of the data
from the sender to the receiver points. The links are often described in terms of their ability to
send and receive signals as part of the communication system. There are two modes of
communication generally referred to as the simplex and duplex. This is a classification based on
the direction or flow of data or information. For the simplex mode of communication, data flows
in one direction only, for instance, home radio communication or broadcasting. The duplex mode
refers to the communication where the sender and receiver can communicate to each other. The
half-duplex allows one speaker at a time while the full-duplex allows for information to flow
both ways at the same time [2].
The fiber optic link is a typical communication link that uses the optical fiber instead of
the copper or aluminum wire [3]. The fiber communication system comprises of the transmitter,
receiver, optical fiber, and the connectors. During transmission, the engineers focus on
converting the information into a form compatible with the communications medium. The
conversion is done using an analog-to-digital converter. It is crucial to note that information
transmitted directly from a computer network is already in digital form [4]. The digital pulses are
used to flash a powerful light source in binary form. Two kinds of light sources are used
depending on the type of fiber cable. For a multi-mode fiber which transmits over short distance,
the light emitting diode is used whereas the solid-state laser is used in the single-mode fiber
which transmits a single information signal over very long distances, up to several hundred
kilometers [5]. Alternatively, one can use a semiconductor device that generates an extremely
intense single frequency light beam. The light beams are fed into the FOC at an angle, θ ≥ 00
On the receiver end there is another light sensitive device that is known as the photocell
or the light detector that detects the light pulses. The photo detector converts the light pulses into
an electrical signal. The electrical pulses are amplified and reshaped back into digital form. The

light sources at the sender and receiver points must be capable of operating at the same data rate.
The circuitry that drives the light source and the circuitry that amplifies and processes the
detected light must both have suitable high-frequency response [6]. The fiber is required to carry
the information signals without distortions at the set data rate. For the single mode transmission
FOC, repeater units are used to restore the signal strength that may attenuate while propagating.
Special relay stations are used to pick up light beams, convert them back to electrical pulses that
are amplified and then they are retransmitted on another beam. There are several stages of
repeaters that may be needed over very long distances. The attenuation problem occurs as a
universal problem for all the transmission cables, for instance, the electrical copper cables.
Some merits that are obtained from using FOC over other wire systems are the
elimination of conventional problems such as ringing, cross talk, electromagnetic interference,
and other induced errors. Some of the advantages that FOC offers are:
(i) High bandwidth; more information can be carried by each fiber as compared to its
equivalent copper cable.
(ii) Noise immunity; fiber can withstand environmental conditions such as salt,
pollution and radiation with no resulting corrosion and minimal nuclear radiation
effects, so it is more reliable.
(iii) Inherent radiation hardness
(iv) Reduced weight
(v) Low bit error rate size and it is more secure and private.
(vi) Weight and volume reduction as compared to the bulky copper cable.
There are many uses of fiber; can be used as sensors to measure the strain, temperature, pressure,
and other quantities by modifying a fiber so that the quantity to be measured modulates the
intensity based on the losses, phase, polarization, wavelength, or transit time.

Figure 1 Fiber optics communication system-wavelength division multiplexing
AIMS & OBJECTIVES
1. To identify all the physical quantities that can be measured using fiber optics technology
2. To classify the optical fiber-based sensors based on their technical operating principles.
3. To explain in detail the principles of operation of the fiber optics-based sensors used to
measure such quantities.
4. To discuss the performance, advantages and disadvantages of using the fiber optics-based
sensors in comparison to the traditional sensing techniques.
5. To multiplex and de-multiplex the different light wavelengths for commercial infrared-
based communications systems, specialized components; minimizing the losses.

RESEARCH FINDINGS & OBSERVATIONS
Table 1 Part 1: Digital/TTL -01
Input Output Losses
Port Amplitude Port
B/A
Port
C
Port
D
Total
Green 1 (2
Khz)
2.6 2.5 2.5 5 200%
Green 1 (2
Khz)
2.6 2.5 2.5 5 200%
Green 1 (100
Khz)
2.8 2.8 2.8 5.6 200%
Green 1 (100
Khz)
2.8 2.8 2.8 5.6 200%
Table 2 Part 2: Digital/TTL-02
Input Output Losses
Port Amplitude Port
B/A
Port
C
Port
D
Total
Red 1 (2
Khz)
2.8 2.8 2.8 5.6 200%
Red 1 (2
Khz)
2.8 2.8 2.8 5.6 200%
Red 1 (100
Khz)
2.7 2.7 2.7 5.4 200%
Red 1 (100
Khz)
2.7 2.7 2.7 5.4 200%
Table 3 Part 3: Testing for crosstalk
Inputs
(Shape/Amplitude)
Outputs
(Shape/Amplitude)
Signal #1 Signal #2 Signal #1 Signal #2 Signal #1 Signal #2
1 Analog
2Khz
Analog 2
Khz
2.0 2.0 2.0 2.0
2 Analog
2Khz
Analog 100
Khz
2.0 2.0 2.0 2.0
3 Digital 2
Khz
Digital 2
Khz
2.6 2.6 2.6 2.7

4 Digital 2
Khz
Digital 100
Khz
2.9 2.9 2.9 2.9
5 Analog
2Khz
Digital 2
Khz
2.7 2.0 2.7 2.0
6 Analog
2Khz
Digital 100
Khz
2.0 2.8 2.0 2.8
IMPLEMENTATION
Comparing the results obtained in part 3 with the WDM- wave division multiplex
Power budget implementation
PB: PRX ≥ PMIN
Where PRX−received power ,∧PMIN −minimum power at a certain BER
PRX=PTX −Total losses+Total Gain−Pmargin
PTX−transmitted power
Pmargin ≈ 6 dB
To obtain the loss,
Loss , L=LIL+ Lfiber + Lconn + Lnon−linear
These refer to the insertion losses, fiber losses, connector loss, and the non-linear loss.
To obtain the gain,
Gain=Gai namp+Gnon−linear
To obtain the dB of the system,
dB=10 log ( P1
P2 )
The fiber-based sensors in the technical operating principles
These sensors measure the properties of their surroundings. They can measure anything which
changes the way light travels through the fiber or alters the properties of light. There are a

number of physical quantities that can be measured using the fiber optics technology such as
temperature, pressure, strain, displacement, acceleration, flow rate, vibration, chemical
concentrations, electrical and magnetic fields, and rotation rate. The sensors can be used in
explosive environments, corrosive environments, hot environments, and remote sensing [7].
Some of the commonly used sensors are:
(i) Amplitude-and intensity-based sensors
(ii) Frequency- and wavelength- varying sensors
(iii) Polarization and phase-modulating fiber-optic sensing
Principles of operation of the fiber optics-based sensors used to measure such quantities are such
as the micro bending, interferometric effects, refractive index change, polarization change, fiber
length change, fiber diffraction grating effects, and the Signac effect [8].
CONCLUSION
In a nutshell, the report covers all the objectives and aims set out in the coursework. The fiber
communication system is efficient and effective in the delivery of information especially over
very long distances as well as in hostile environment where human intervention is least required.
The communication system allows for multiplexing and demultiplexing, such that the data rates
and communication method performance is largely improved.
RECOMMENDATIONS
(i) Improvement of the micro bending sensor detection to ensure that less light signals
are lost as a result of the FOC bending beyond the set or standard maximum angle of
bending.

REFERENCES
[1] "A multiplexing/Demultiplexing Transceiver for 565-Mbits Fiber-Optic Links," Solid-State
Circuits IEEE ournal of Telecommunications, vol. 20.
[2] T. Benson, "Etched-wall bent-guide structure for integrated optics in the III-IV
semiconductors," Lightwave Technology ournal of Engineering, vol. 2, pp. 31-34.
[3] N. M and R. A, "FWM minimization in WDM optical communication systems using the
asymmetrical dispersion managed fibers," Interrnational Journal for Light and Electron
Optics, vol. 123, no. 9, pp. 758-760, 2012.
[4] X. Wang and K. K, "Analysis of beat noise in coherent and incoherent time-spreading
OCDMA," IEEE/OSA Journal of Lightwave Technology, vol. 22, no. 10, pp. 2226-2235,
2004.
[5] F. Franz, M. Knapek, H. Hoachim and R. L. Walter, "Optical Communications for High-
Altitude Platforms," IEEE Journal of Selected Topics in Quantum Electronics, vol. 16, no. 5,
pp. 113-119, 2010.
[6] S. Prachi, "A review of the Development in the Field of Fiber Optic Communication
Systems," International Journal of Emerging Technology and Advanced Engineering, vol. 3,
no. 5, pp. 113-119, 2013.
[7] D. S. Rajpoot, D. P. Singh, S. Solanki and S. J. Yasin, "Future trends in Fiber Optics
Communication," International Journal on Cybernetics & Informatics (IJCI) , vol. 6, no. 1-
2, pp. 1-6, 2017.
[8] T. Shake, "Confident performance of encoded optical CDMA," IEEE/OSA Journal of
Lightwave Technology, vol. 23, pp. 1652-1663, 2005.

APPENDIX
(I) APPENDIX I
Report PowerPoint presentation
(II) APPENDIX II
Figures included in the report
715397-Presentatio
n (1).pptx