Fiber optic cable types

The fiber optic cable is to be used a variety of situations such as underground, outdoor poles or submerged underwater. The structure of cable depends on the situation where it is to be used,  but the basic cable design principles remain the same.
The requirement of optical fiber material is to be transparent for the efficient transmission of light.

The mechanical property of cable is one of the most important factors for using any specific cable. The maximum allowable axial load on cable decides to the length of the cable can be reliably installed. That are several benefits of a fiber optic cable is a flexible, transparent fiber made by drawing plastic or glass to a diameter slightly thicker than that of human hair.

Fiber arrangements :

  • Several arrangements of fiber cables are done to use it for different application in a cable. The most basic form is two fiber cable is proper design. Shows basic two fiber cable design as given below. It is also known as a basic building block of fiber cable.
  • Multiple fiber cables can be combined together using some similar techniques. 
  • The basic fiber building blocks are used to form a large cable. These units are bound on a buffer material which acts as strength element along with an insulated copper conductor types of materials. The fiber building blocks are surrounded by paper tape, PVC jacket, yarn, and an outer sheath. 
Fiber optic  cable 

There are many types of fiber optic cable available in fiber optical communication. In general, there are two types of fiber optic cables are available :

1. Simplex cable
2. Duplex cable


1. Simplex cable :


In simplex cable single strand surrounded by around  900 um tight buffer then the aramid yarn and finally the outer jacket are available.

A jacket is used in 2 mm or 3 mm plenum or riser types of jacket.



2. Duplex cable:


 In duplex cable strands of fiber optic cable attached at the center point. Cable surrounded by a 900 um buffer then a layer of kevlar and finally the outer jacket there.

A jacket is used in 2 mm or 3 mm plenum or riser types of jacket.




A number of a core are bundled in a plastic type of ducts. In case, ease identification of individual fibers is color-coded types. Shows some example of the color coding in the optical cable used by manufactures.

1 - Blue
2 - Orange
3 - Green
4 - Brown
5 - Grey
6 - White
7 - Red
8 - Black
9 - Yellow
10 - Violet
11 - Pink or light blue
12 - Turquoise or netutral

Fiber optic cable material

Materials are used for optical fiber :


 The material requirement of fiber optic cable for glass and plastic. They offer widely different characteristics and therefore fibers made from the two different substances and find uses in very different applications.

The main requirement of fiber optic material to be given below :
  • Fiber material must be required with compatible the cladding material
  • It must be possible to draw long thin fiber from the material used
  • The material must be used to be transparent for efficient transmission of light

Glass and plastics materials have fulfilled this requirement:


 Most fiber consists of silica or silicate. Various types of low loss and high loss glass fiber are available to suit the requirement. Plastic fibers are not too much popular because of its high attenuation so they have better mechanical strength.

Glass fiber :

Glass fiber made by materials fusing mixtures of metal oxides having a refractive index of 1458 at 850 nm. For changing the refractive index different oxides like B2O3, GeO2 and P2O5 are added as dopants. 

One important criterion is that the refractive index of the core is greater than that of the cladding, hence some important composition is used such as given below :

Composition :

1 : Core type -  GeO2 - SiO2  Cladding type - SiO2 
2 : Core type  -  P2O5  - SiO2  Cladding type - SiO2 
3 : Core type - SiO2  Cladding - B2O3 - SiO2 
4 : Core type - GeO2 - B2O3 -  SiO2  Cladding type - B2O3  - SiO2 

The principal raw material for silica is sand and glass materials. The fiber materials composed of pure silica is called as silica glass. The desirable properties of silica glass are given below:
  • Resistance to deformation even at high temperatures.
  • Good chemical durability. 
  • Better transparency.
  • Resistance to breakage from chemical thermal shocks.
Other types of glass fibers are :
  • Halide glass fibers.
  • Active glass fiber.
  • Chalcogenide glass fiber.
  • plastic optical fibers. 

Function of MSC

MSC full form Mobile Switching Center is the centerpiece of an NSS full form network switching subsystem. 

MSC most commonly used with a communications switching function, such as call set-up, release, and routing. 

MSC is a telephone exchange that makes the connection between mobile users within the network, from mobile users to the public switched telephone network and also from mobile users to other mobile networks.

Function of BSC

BSC full form is Base Station Controller reserve radio frequency for communication and manages handovers between BTS. BCS connected to a single MSC. 

Some function of BSC are following below :

  • To control BTS.
  • Radio resource management. 
  • Handoff management and control.
  • It handles radio channel set up and frequency hopping. 
  • The BSC is physically connected through leased lines or microwave links to the MSC. 

Function of OMC

OMC full form is operations and maintenance center used in the switching system in GSM network architecture is connected to all equipment in the switching system and to the BSC. 


The implementation of ( operations and maintenance centers) OMC is called the operation and support system.

Now we can also check the function of OMC :

  • Used in security management. 
  • Used in maintenance tasks.
  • Used in network configuration, operation and performance management. 
  • Used in administration and commercial operations like subscriptions and terminals charging and in statistics. 

Full form of OMC

What is the full form of OMC?


 Answer :

  • Operations and Maintenance Center 


What does OMC mean?


OMC used in the switching system in a GSM network is connected to all equipment in the switching system and to the BSC. You can check the full form of BSC. 

The implementation of ( Operations and Maintenance Center ) OMC is called the operation and support system. 

Graded index fiber

Definition of Graded-index fiber :


 An optical fiber with a core having a refractive index that decreases with increases radial distance from the fiber axis. The most common refractive index for a graded index fiber is very nearly parabolic. The parabolic result in continual refocusing of the rays in the core, and compensates for multimode distortion.

 The graded index fiber has a core is made from many layers of glass. In the graded index fiber the refractive index is not uniform within the core, it is highest at the center and decreases smoothly and continuously with distance towards the cladding side. The refractive index profile across the core that takes place in the look like parabolic nature.

In graded-index fiber, the light waves are bent by refraction towards the core axis and they follow the curved path down the fiber length side. This result because of change in refractive index as moved away from the center of the core side.
Graded index fiber 

Multimode graded-index fiber :


The core size of multimode graded index fiber cable is varying from 50 to 100-micrometer range. 

In this fiber, the light ray enters the fiber at many different angles. So in graded index fiber, the light propagates across the core toward the center it is intersecting a less dense to more dense medium. This article gives some advantages of graded index fiber to know more details about it 

Therefore the light rays are being constantly being refracted and the ray is bending continuously. This cable is mostly used for long distance communication system.

Multimode graded index fiber

Some important point of graded index fiber :
  • Graded index fiber data rate is very high.
  • The path of light is helical in manner.
  • Graded index fiber is of only one types that is a multimode fiber.
  • Coupling efficiency is low.
  • In graded-index fiber, the diameter of the core is about 50 micrometer in the case of multimode fiber.
  • Attenuation is less.
  • Refractive index is non-uniform.
  • Graded index the bandwidth is high.  
  • It is mostly used in local and wide area networks.

Difference between step index fiber and graded index fiber

There are two types of fiber known as step index and graded index fiber.  step index fiber is fiber type cylindrical waveguide core with inner core has a uniform refractive index of n1 and the core is surrounded by an outer cladding with a uniform refractive index of n2. While the graded index fiber has a core made from many layers of glass and also have the graded index fiber, the refractive index is not uniform within the core. Here this article gives the difference between step index fiber and graded index fiber to know more details about this topic.

Step index fiber :

  • In this fiber data rate is very slow.
  • The ray path of light propagation is looked like Zig Zag manner. 
  • Step index fiber of two types of fiber known as mono-mode fiber and multimode fiber.
  • Coupling efficiency with fiber is very high.
  • In step-index fiber the diameter of the core is about 50 -200 micrometers in the case of multimode fiber while  In 10 micrometers in the case of single-mode fiber.
  • Attenuation is too much more. 
  • The refractive index of the core is high.
  • The bandwidth is low.
  • It is mostly used in the application of local network communication. 

Graded index fiber :

  • Graded index fiber data rate is very high.
  • The path of light is helical in manner.
  • Graded index fiber is of only one type that are called as multimode fiber.
  • Coupling efficiency is very low.
  • While graded-index fiber the diameter of the core is about 50 micrometer in the case of uses multimode fiber.
  • Attenuation is less.
  • The Refractive index is non-uniform.
  • The bandwidth is high.
  • It is most commonly used in local and wide area networks.

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Step index fiber

The step index fiber is a cylindrical waveguide core with inner core has a uniform refractive index of n1 and the core is surrounded by an outer cladding with a uniform refractive index of n2.

In this fiber, the cladding refractive index ( n2 ) is less than the core refractive index ( n1 ) but there is some abrupt change in the refractive index at the core-cladding interface for using simple step-index fiber. 

The propagation of light wave within the core of step index fiber takes the path of a meridional ray. Ray follows a Zig Zag path of straight line segment. 

Depending on the refractive index profile of fiber and modes of fiber there exist two types of step index fiber  called as : 
  1. Single mode step index fiber type
  2. Multimode step-index fiber type

1. Single mode step index fiber


Single mode step index fiber has a central core that is sufficiently so small so that there is essentially only one path for light ray through the cable. 

The light ray propagates in the fiber through reflections. Typical core size is 2 to 15 micrometer. so single mode fiber is also known as the fundamental or monomode fiber.

Single mode fiber will permit only one mode to propagate and also does not suffer from mode delay difference. 

These are primarily developed for the 1300 nm window but they can be also be used effectively with time multiplex and wavelength division multiplex system operating in 1550 nm wavelength region.

The core fiber of a single mode fiber is very narrow compared to the wavelength of light is to be used. Therefore, only one single path exists through the cable core through which light can travel. 
(a) Multimode step index fiber type,  (b) Step index fiber type

2. Multimode step index fiber 


Multimode step-index fiber is the most widely used in optical fiber communication. It is easy to manufacture and also its core diameter is 50 to 1000 micrometer. 

In this mode, the light ray is propagated using the principle of total internal reflection. Since the core index of refraction is too much higher than the cladding index of refraction, so the light enters at less than the critical angle is guided along the fiber.

Light rays passing through the fiber are continuously reflected off the glass cladding towards the center of the core at different angles and also have lengths, limiting overall bandwidth.

One of the disadvantages of multimode step-index fibers is that the different optical length caused by various angles at which light is propagated relative to the core devices, causes the transmission bandwidth to be fairly small. So multimode step index fiber is typically only used in an application requiring of less than 1 km.  


Some important point of step index fiber :

  • The data rate is very slow.
  • The ray path of light propagation is looked like Zig Zag manner.
  • Step index fiber of two types of mono-mode fiber and multimode fiber whereas using step index coupling efficiency with fiber is too high.
  • In step index fiber the diameter of the core is about 50 - 200 micrometer while in the case of multimode fiber and 10 micrometers in the case of single mode fiber type.
  • Attenuation is more.
  • The refractive index of the core is high.
  • The bandwidth is low.
  • It is mostly used in local network communication.

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Features of CDMA

The main features of the CDMA system are given below :

  • The CDMA system users share the same frequency either  TDD or FDD can be used.
  • CDMA has a soft capacity limit.
  • In the CDMA system the number of users increases, the system performance decreases.
  • While using in CDMA system near-far problem arises at the receiver end.
  • Multipath fading can be reduced as the signal is spread over a large spectrum.
  • CDMA is an interference-limited system.
  • Higher frequency reuse. 
  • CDMA uses the co-channel cell.  So the spatial diversity can be used to provide soft handoff.
  • The channel data rates are very high. Hence, the symbol duration is short and less than the channel delay spread. A rake receiver can be used to improve the reception by collecting a time-delayed version of the required signal.
  • CDMA is a protocol implemented in a wireless network device. It is the most famous protocol and implemented in all over the world because it offers several advantages.
  • There is not a sheer cutoff in the number of users that it can support unlike TDMA full form or any other traditional cellular device. 
  • TDMA and FDMA both systems are suffering from hard hand-off. CDMA system has to eliminate the hard handoff by using a technique logically labeled the soft hand-off. 
  • CDMA has a too much higher user capacity than that of the TDMA disadvantages or FDMA disadvantages system.
  • CDMA is a secures its signals by encoding the user transmission in a unique code.

Raman amplifier

Introduction to Raman amplifier :


Raman amplifier is an optical amplifier based on main to be Raman gain, which results from the effect of stimulated called as Raman scattering. In this medium, the active medium is generated or often at an optical fiber, although it can also be a bulk crystal, a waveguide in a photonic integrated circuit, or a cell with a liquid or gas medium device. An input signal can be amplified while a counterpropagating with a pump of a beam, the wavelength of which is typically a few tens of nanometers shorter. For silica fibers, the maximum gain is obtained for a frequency offset of around = 10-15 THz between pump and signal depending on the composition of the fiber core. Here this article gives information about the most important amplifier known as the Raman amplifier to better understanding this topic.


Features of Raman amplifier :

  • It can be operated in the different wavelength region
  • Provided that a suitable pump source is available
  • In this amplifier the gain spectrum can be tailored by using different pump wavelength simultaneously
  • This amplifier also requires high pump power, it also requires high pump brightness but it can also generate high output powers
  • A greater length of fiber is required
  • It can have a lower noise figure
  • This amplifier also has a fast reaction to changes in pump power, particularly for copropagating pump and very different saturation characteristics 

Working principle :


It is based on the stimulated Raman scattering effect. Power transferred in the optical signal is known as the Raman effect and amplification. In this above method, Raman amplification provides self-phase matching between the pump and signal with a broad gain bandwidth response generated. The pumping signal can be propagated in either direction of fiber called as forward and backward pumping.

Basically, the Raman gain is dependent on several terms following  given below :
  • Fiber length
  • Fiber length
  • Fiber attenuation
  • Fiber core diameter
  • Optical pump power 
The figure is shown that below a typical Raman amplifier. The circulator as well as a pump shown in the figure, it lases comprise the two key elements of the Raman optical amplifier. The circulator is basically used for injecting light back into the transmission path minimal optical loss.


Typical Raman amplifier configuration

Advantages of Raman amplifier :

  • Compatible with installed SM fiber.
  • Variable wavelength amplification possible.
  • A very broadband operation may be possible.
  • Lower crosstalk.
  • Can be used extends  EDFAs full form.

Disadvantages of Raman amplifier :

  • High pump power requirements.
  • Sophisticated gain control needed.
  • Noise is also an issue.

Advantages and disadvantages of raman amplifier

Raman amplifier is also a relatively mature optical amplifier in the different amplifier system. In this  amplifier, the optical signal can be achieved by using stimulated Raman scattering, stimulated Brillouin scattering or stimulated for photon mixing giving parametric gain by injecting a high power laser beam into an optical fiber. Here this article gives the advantages and disadvantages of the Raman amplifier to know more details about the Raman amplifier. 

Advantages of Raman amplifier :
  • Compatible with installed SM fiber
  • Variable wavelength amplification possible
  • A very broadband operation may be possible
  • Can result in lower average power over a span, so it good for lower crosstalk
  • Can be used extends  EDFAs
  • Flexible gain wavelength
  • Low noise
  • Simple structure
  • The non-linear effect can be reduced
Disadvantages of Raman amplifier :
  • High pump power require
  • Sophisticated gain control needed
  • Noise is also an issue
  • Low efficiency
  • High cost

Advantages and disadvantages of semiconductor optical amplifier

Semiconductor optical amplifier is one type of laser diode without end of the mirror. it is the latest technology that provides high-speed switching capability, high extinction ratio, gain etc. Here this article gives the advantages and disadvantages of semiconductor optical amplifier to know more details about semiconductor optical amplifier (SOA).

Advantages semiconductor optical amplifier :
  • Small size
  • Electrically pumped
  • Smaller output power then EDFA
  • Less expensive then EDFA
  • It can be run with a low power laser
  • It provides all types of nonlinear operation like cross-phase modulation, cross gain modulation can be conducted
Disadvantages of  semiconductor optical amplifier :
  • Lower gain
  • High non-linearity
  • Higher noise
  • Polarization dependence
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Advantages and disadvantages of EDFA

The most popular material for long-haul telecommunication application widely used in silica doped with erbium, which is known as an erbium-doped fiber amplifier. So we will check the advantages and disadvantages of EDFA to know more about EDFA. 

 Advantages of EDFA :
  • Gain is an excess of  up to 40 to 50 dB
  • Low noise 3-5 dB, it is suitable for long-haul application
  • High pump power utilization
  • Good gain stability
  • The high energy conversion efficiency
  • High gain with little crosstalk
  • This amplifier is fully compatible with the rest of the fiber optic transmission link
  • Flatness can be improved gain flattening optical filter
  • Amplify wide wavelength band in the range of  around 1530 nm  to 1560 nm region, with a relatively flat
Disadvantages of EDFA :
  • Size of EDFA is large
  • Fixed gain range
  • Gain up flatness
  • Optical surge problem
  • High pump power consumption
  • It cannot be integrated with other semiconductor devices
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Erbium doped fiber amplifier

Introduction of Erbium-doped fiber amplifier :

EDFA stands for erbium-doped fiber amplifier, An optical amplifier or types are also called erbium-doped fiber amplifier or EDFA. An Erbium-doped fiber amplifier is an optical amplifier that amplified a modulated laser beam directly, without electron-optical or optoelectronic conversion. The most popular material for long-haul telecommunication application widely used in silica doped with erbium, which is known as Erbium doped fiber amplifier or EDFA. Here this article to give a brief introduction to the most deployed fiber amplifier called the erbium-doped fiber amplifier.

Working principle :

Amplification mechanism : 

The operation of an EDFA by itself normally is limited to the range of 1530 to 1560 nm region. The energy level diagram of erbium ions in silica is shown in the figure.
Erbium-doped fiber amplifier
The erbium atoms in silica are called Er3+ ions with three lost electrons in its orbit. The raising of ions to higher energy levels is achieved by two types of pump level.

 1. Metastable state :
The metastable state is a state from which the lifetime for the transitions from this state to the ground state is very long compared with the lifetimes to the states that led to this level. 

  2. Stark splitting :
The metastable, the pump band state and ground state levels are closely spaced energy levels form the manifold called stark splitting.


Energy level diagram 
This article also gives the advantages and disadvantages of EDFA below :

Advantages of EDFA :
  • Gain is an excess of 40 to 50 dB.
  • Low noise 3-5 dB, it is suitable for the long haul application.
  • High pump power utilization.
  • It is fully compatible with the rest of the fiber optic transmission link.
  • Flatness can be improved gain flattening optical filter.
  • Amplify wide wavelength band in the range of 1530 nm to 1560 nm region, with a relatively flat.
Disadvantages of EDFA :
  • Size of EDFA is large. 
  • High pump power consumption.
  • It cannot be integrated with other semiconductor devices.

Semiconductor optical amplifier

Introduction to semiconductor optical amplifier :

An optical amplifier is nothing but a laser diode without feedback. Which introduce in 1990. It is mainly used the inline optical amplifier. Semiconductor optical amplifier is a laser diode without an end mirror. It is a  most important technology provides high-speed switching capability, high extinction ratio, gain etc. There are many types of optical amplifier namely semiconductor optical amplifier ( SOA ) like erbium doped optical amplifier ( EDFA ), Raman amplifier. This article will make a clearer introduction to semiconductor optical amplifier ( SOA ).

Some key point in semiconductor optical amplifier :
  • Similar to laser but with nonreflecting ends and broad wavelength emission.
  • In this amplifier, incoming optical signal stimulates emission of light at its own wavelength.
  • The process continues through the cavity to amplify a signal.
  • Semiconductor optical amplifier consumes less power and it can use fewer component.
  • Active medium consists of an alloy semiconductor ( Ga, P, In, As ).
  • It works in both attenuation windows, 1300 nm, and 1500 nm.
  • It very broad gain spectrum.
  • High fiber to fiber gain 20 dB.
  • Semiconductor optical amplifier has rapid gain response 1 ps to 0.1 ns.
A basic structure of SOA :

An SOA  work in a similar way to a basic laser. As a name suggested are used to amplify the optical signal. A typical structure of InGaAsP/InP structure of given below. The structure is much the same, with two specially designed slabs of semiconductor material on top of each other, with another material between them forming the active layer. The smaller bandgap intrinsic region has a smaller refractive index than the wider bandgap p doped and n doped quasineutral region. The intrinsic region forms the core of the optical waveguide and the quasi-neutral region form the claddings. Current injection into the intrinsic region can create a large population of electron and holes.

During the operation as an optical amplifier, light is coupled into the waveguide at Z=0. As the light propagates inside the waveguide it gets amplified and finally when the light at Z=L, its power is much higher compared to what it was at Z=0.




There are two major types of Semiconductor optical amplifier is :

  1. Fabry Perot amplifier ( FPA )
  2. Traveling wave amplifier ( TWA )
Now here this article you have to also check it out the advantages and disadvantages of semiconductor optical amplifier below :

Advantages semiconductor optical amplifier :
  • Small size.
  • Electrically pumped.
  • Smaller output power then EDFA.
  • Less expensive then EDFA.
  • It can be run with a low power laser.
  • In this amplifier all types of nonlinear operation like cross-phase modulation, cross gain modulation can be conducted.
Disadvantages of  semiconductor optical amplifier :
  • Lower gain.
  • High non-linearity.
  • Higher noise.
  • Polarization dependence.
Application of semiconductor optical amplifier :
  • Power booster
  • Inline amplifier
  • Preamplifier 

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