Fiber Communication System: Optical Sensors and Multiplexing Mechanisms

The report focuses on the fiber communication system, optical sensors, and multiplexing mechanisms. It explains the operation of fiber optic sensors and the economic perspective of multiplexing. The report also discusses the trends and future scenarios of fiber communication systems.

FEDERATION UNIVERSITY OF AUSTRALIA
ITECH 7410
SOFTWARE METHODOLOGIES
NAME
REGISTRATION NUMBER
COURSE PROFESSOR (TUTOR)
Date of Submission

Fiber Communication System
EXECUTIVE SUMMARY
The main focus of this report is on the fiber communication system. The optical fiber is
the backbone of the modern communication network. It carries all long distances voice data and
other multimedia forms of communication. Fiber communication systems are used in many
fields such as the power engineering, biomedical, optical sensing for structural monitoring and
VLSI in intra-chip communications. The device detects events or changes in the physical
quantities and provide a corresponding optical output. The sensor will modulate an optical signal
which when demodulated yields precise quantitative information. The economic perspective of
multiplexing benefits the organization hosting the FOC as the transmission costs less in terms of
physical resources such as cables and time. A corresponding multiplexer, or demultiplexer, is on
the end of the high-speed line and it is used to separate the multiplexed signals
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TABLE OF CONTENTS
EXECUTIVE SUMMARY.........................................................................................................................1
REPORT AIMS & OBJECTIVES..............................................................................................................3
INTRODUCTION.......................................................................................................................................3
Fiber communication systems.................................................................................................................3
Optical sensors........................................................................................................................................4
Multiplexing Mechanisms.......................................................................................................................7
CONCLUSION.........................................................................................................................................10
RECOMMENDATIONS...........................................................................................................................10
WORKS CITED........................................................................................................................................10
LIST OF FIGURES
Figure 1 Optical Data Communication Flow. [Source: VLSI -Optical Leaflet]...........................................4
Figure 2 Optical Data Communication [Shariff University]........................................................................5
Figure 3 Optical Data aggregation [Source: Optical Sensor Pamphlet].......................................................6
Figure 4 Optical Sensors [Source: Optical Sensor Leaflet]..........................................................................7
Figure 5 Fiber Cable Transmission and Reflection [Source: Strathy University]........................................8
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REPORT AIMS & OBJECTIVES
(i) To determine the physical quantities that the optical fiber technology measures
(ii) To categorize the fiber optic sensor with respect to their technical operating
principles.
(iii) To explain the operation of the fiber optic sensors in their surroundings or
implementation environment.
INTRODUCTION
Fiber communication systems
The optical fiber is the backbone of the modern communication network. It carries all long
distances voice data and other multimedia forms of communication. The information revolution
can be attributed to the evolution of optical fiber in data communications. It is preferred because
of the low attenuation, very high bandwidth in the communication channel especially in the
single mode fiber, its enormous capacity, and the system adds an optical layer that guarantees
flexibility. Fiber communication systems are used in many fields such as the power engineering,
biomedical, optical sensing for structural monitoring and VLSI in intra-chip communications.
Figure 1 Optical Data Communication Flow. [Source: VLSI -Optical Leaflet]
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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. The fiber carries light
signals as single mode, multimode, step index, and as graded index fiber. The optical transmitter
converts the electrical information for the computer network to the optical format. For the multi-
mode fiber, a light emitting diode is used while for a single mode fiber, a laser diode is used. The
reverse procedure is carried out on the receiving end. The communication system transmits
information over very long distances and as a result, repeaters are used to receive weak light
signals, clean them up, and amplify them for retransmission.
With the advent of newer technology in the data and network communications field, the
transmitted signals need further processing such as switching, wavelength conversion, signal
reshaping, and add-drop multiplexing. The scheme we focus on in this report is the multiplexing
and demultiplexing technique used to transmit multiple sources of data along a single mode fiber
for very long distances. The flow can be illustrated as shown below,
Figure 2 Optical Data Communication [Shariff University]
The input is usually format, set within a given bandwidth following a given data and network
protocol. The optical transmitter performs modulation, power alterations, and wavelength
modifications. The communication channel, in this case, the single mode fiber, experiences loss,
light signal dispersion, 4-wave mixing, distortion and in most cases amplification using
repeaters. The optical receiver checks on the bandwidth on reception and compares it to the
sending one. Amount of information that can be transmitted is directly related to the frequency
range over which the carrier operates, increasing the carrier frequency theoretically increases the
available transmission bandwidth and therefore larger capacity.
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Optical sensors
An optical sensor is a device that picks up external stimulus of the physical quantities such as the
temperature, pressure, and strain. The device detects events or changes in the physical quantities
and provide a corresponding optical output. The sensor will modulate an optical signal which
when demodulated yields precise quantitative information about the measurand. Some of the
problems associated with optical sensors are portability, remote monitoring, cost, ruggedness,
and efficiency. The solutions to the optical sensors are obtained from optical fibers and the OE
components for sensing such as the Fiber optic sensors. According to the alternate school of
thought, the realization of the high sensitivity of optical fibers to external perturbations such as
the phase modulation, micro bending loss in cabling, modal noise and its exploitation for
development of sensors [2]. The high sensitivity of fibers due to long interaction length of light
with the physical variable. Some of the merits of using the fiber optic sensors:
(i) Large bandwidth
(ii) Efficient transmission or low loss
(iii) Immunity to Electromagnetic interference or radio frequency interference and EMP.
(iv) Information security is guaranteed
(v) The geometric versatility
(vi) They are small in size and lightweight
(vii) It guarantees no sparking or fire hazards with single fiber serves both as sensor and
data transmitting channel.
(viii) Allows for multiplexing and spatially distributed sensing and ensures very high
performance.
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Figure 3 Optical Data aggregation [Source: Optical Sensor Pamphlet]
Some sensors are extrinsic such that when the light leaves the transmitting fiber to be changed
before it continues to the detector by means of the return or receiving fiber [3]. The intrinsic
sensors are different in that the light beam does not leave the optical fiber but it is changed whilst
still contained within it.
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Figure 4 Optical Sensors [Source: Optical Sensor Leaflet]
The point sensor detects the variable being measured based on its variation only in the
surrounding of the sensor. The multiplexed sensor tends to have multiple localized sensors that
are placed at intervals along the fiber length and the distributed sensor performs sensing in a
distributed format along the length of the fiber [4].
Other components used are the fiber gratings which are sensing elements. These are photos
inscribed into silica fibers and are a periodic perturbation of the optical fiber core refractive
index created by exposure to intense ultraviolet radiation.
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Figure 5 Fiber Cable Transmission and Reflection [Source: Strathy University]
Multiplexing Mechanisms
It provides high resolution, well-localized sensing regions, absolute measurement, and
linear output. It is insensitive to optical systems and intensity fluctuations. It is capable of
multiplexing several sensors along one fiber and it is very cost-effective.
For digital systems, the commonly implemented systems are the Synchronous optical
networks such as SONET [5]. It is the time division multiplexing optical network standard
employed in North America. It is considered as the de-facto standard for fiber backhaul
networks. The linear multiplexing and de-multiplexing is possible with add-drop-multiplexers.
SONET Optical
Carrier Level
SONET Frame
Format
SDH level and
Frame Format
Payload
bandwidth
(kbps)
Line Rate (kbps)
OC-1 STS-1 STM-0 50,112 51,840
OC-3 STS-3 STM-1 150,336 155,520
OC-12 STS-12 STM-4 601,344 622,080
OC-24 STS-24 – 1,202,688 1,244,160
OC-48 STS-48 STM-16 2,405,376 2,488,320
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OC-192 STS-192 STM-64 9,621,504 9,953,280
OC-768 STS-768 STM-256 38,486,016 39,813,120
OC-3072 STS-3072 STM-1024 153,944,064 159,252,480
With the evolution of the internet and data communications, the many carriers are finding that
their estimates of fiber needs may have been underestimated. There are three ways to expand the
capacity of a data communication system. It can be achieved by installing more cables,
increasing the system bit rate to ensure that more signals can be multiplexed and to perform the
wavelength division multiplexing.
In summary, the
frequency division
multiplexing,
wavelength division
multiplexing, time
division
multiplexing and code
division
multiplexing are the
key techniques used in multiplexing and demultiplexing in the FOC communication system [6].
It simultaneously aims at transmitting two or more signals on a single circuit. The economic
perspective of multiplexing benefits the organization hosting the FOC as the transmission costs
less in terms of physical resources such as cables and time. A corresponding multiplexer, or
demultiplexer, is on the end of the high-speed line and it is used to separate the multiplexed
signals [7].
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The fiber has the capability to transmit hundreds of wavelengths. Once the fiber is in
place, the additional wavelength can be launched by upgrading transceivers. The fiber optic
cable multiplexes many signals from different senders. The multiplexing uses a set of techniques
that allow the simultaneous transmission of multiple signals across a single data link. Under the
analog signals, the frequency and wavelength division multiplexing techniques are used. Under
the digital signals, the time division multiplexing is used [8]. In the FOC communication system,
the wavelength division multiplexing is used to multiplex multiple optical carrier signals on a
single optical fiber by using different colors of the laser light to carry different signals. This is
commonly done when a single mode FOC is used as it transmits data over very long distances
compared to the multi-mode fiber.
The ISDN multiplexer streams is a continuous stream of frames. Each frame contains various
control and sync information.
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SONET, on the other hand, transmits massive data rates such as,
CONCLUSION
In a nutshell, a medium can carry at least one signal at any moment in time, especially in
the case of the single mode fiber. The multiple signals sent at the senders point share one
medium and the medium must be divided so as to give each signal a portion of the total
bandwidth.
RECOMMENDATIONS
Trends and future scenario
Radio frequency signals are transmitted over fiber to provide broadband wireless access. It is an
emerging trend in the data communications field [4]. Some of the places that have considered the
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implementation of the same are such as Olympics London and Niagara Tunnel. The single
Radio over frequency link can support both voice and data simultaneously. The new generation
of optical communication is still evolving. Not only long-haul optic communication, the fiber to
home and the local networks may be controlled optically and fully in the coming decade. There
are plans to increase the number of underwater and underground fiber network cables to ensure
faster and reliable data communication.
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REFERENCES
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[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] 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.
[4] T. Shake, "Confident performance of encoded optical CDMA," IEEE/OSA Journal of
Lightwave Technology, vol. 23, pp. 1652-1663, 2005.
[5] 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.
[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] 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.
[8] 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.
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