Step Index Optical Fiber - Multi Mode and Single Mode Step Index Fibers - Step Index Optical Fibre
77.7 هزار بار بازدید -
7 سال پیش
-
This video lecture describes, What
This video lecture describes, What are step index optical fibers and what are two types of step index optical fibers on the basis of modes. These are single mode step index fibers and multimode step index fibers. The difference between single mode and multimode is also made clear here.
On the basis of refractive index profile, we can classify optical fibers into two types-
Step index fibers and Graded index fibers
Definition of step index fibers-
Step index fibers are the optical fibers, that have some constant value of refractive index in the core and some other constant value in the cladding.
Step index fibers (mathematical representation)-
n(r) = n1 ; r less than a (Core)
n2 ; r greater than a (Cladding)
Here n1 greater than n2
Here n1 is refractive index of the core and n2 is refractive index of the cladding
'a' is radius of the core
Classification of step index fibers (based on modes of propagation)
Multimode step index fibers
Single mode step index fibers
will show you, how the light rays travel inside the core of the optical fiber, in case of both multimode step index fiber and single mode step index fiber. The images also show plots.
Now let's observe the plots and working structures of both multimode and single mode step index fibers one by one-
Multimode step index fiber
Since the diameter of the multimode step index fiber is large ( more than 50 micrometre), therefore it can support multiple modes of light. Therefore it is known as multimode step index fiber. As you can see in the image above, that refractive index of the core is n1 and that of cladding is n2. Since it is the step index fiber, therefore the refractive index of the core is constant (n1), and does not change as we move away from the axis of the core, within the core. But as we reach to the core-cladding interface, the refractive index inside the cladding changes suddenly to n2.
Since it makes sudden (step) change in the refractive index at the core-cladding interface. This is the reason, why it is called as step index fiber and as it supports multiple modes, so called as multimode step index fiber.
Since refractive index of the core (n1) is more than the refractive index of the cladding (n2), therefore Total Internal Reflection (TIR) phenomenon takes place, as the light rays move from the denser medium to the rarer medium (core to cladding).
Single mode step index fiber
It is also a step index fiber, but due to its small diameter of the core (2-10 micrometre), it can support only single mode of light. Therefore this type of step index fiber is known as single mode step index fiber. You can see the image shown above, how a single mode of light is propagating through the core of The Optical Fiber. Since it is a type of step index fiber, therefore the refractive index of this optical fiber makes step (sudden) change at the core cladding interface. It is also clear from the plot given for the single mode step index fiber.
Comparison of multimode step index fiber and single mode step index fiber, on the basis of following parameters-
Diameter
Multimode step index fiber has larger diameter of the core (more than 50 micrometer).
Single mode step index fiber has smaller diameter (2-10 micrometres)
Number of modes
Propagation of multiple modes is possible in case of Multimode step index fiber.
Only single mode is present in single mode step index fiber.
Dispersion
Dispersion is high in case of Multimode step index fiber, due to differing group velocities of various modes.
Dispersion is low, which is due to broadening of the single pulse of the light in case of single mode step index fiber.
Bandwidth
Bandwidth is low multimode step index fiber.
Bandwidth is higher in single mode step index fiber.
Coupling
In case of multimode step index fibers, spatially incoherent optical sources (LEDs), can be coupled easily and efficiently due to its large diameter. Due to large numerical aperture (NA), easy coupling is possible with optical sources.
While in single mode step index fibers, coupling is not easy due to smaller diameter. Since it has smaller.
Tolerance requirements on optical fiber connectors are higher in case of single mode step index fibers.
Visit My BLOG for more information
https://www.engineeringmadeeasypro.com/
PLAYLISTS on different Topics:
Electronics and Communication (ECE) Lecture Videos (GATE and IES)
Electronics and Communication (ECE) L...
Optical Fiber Communication
Optical Fiber Communication
Optical Fiber Communication in HINDI Videos
Optical Fiber Communication in HINDI ...
#OpticalFiberCommunication #StepIndexOpticalFiber #SingleModeAndMultimode #OpticalFiber #FiberCable #FiberOptics #OpticalFibre #OpticalCable #EngineeringMadeEasy
On the basis of refractive index profile, we can classify optical fibers into two types-
Step index fibers and Graded index fibers
Definition of step index fibers-
Step index fibers are the optical fibers, that have some constant value of refractive index in the core and some other constant value in the cladding.
Step index fibers (mathematical representation)-
n(r) = n1 ; r less than a (Core)
n2 ; r greater than a (Cladding)
Here n1 greater than n2
Here n1 is refractive index of the core and n2 is refractive index of the cladding
'a' is radius of the core
Classification of step index fibers (based on modes of propagation)
Multimode step index fibers
Single mode step index fibers
will show you, how the light rays travel inside the core of the optical fiber, in case of both multimode step index fiber and single mode step index fiber. The images also show plots.
Now let's observe the plots and working structures of both multimode and single mode step index fibers one by one-
Multimode step index fiber
Since the diameter of the multimode step index fiber is large ( more than 50 micrometre), therefore it can support multiple modes of light. Therefore it is known as multimode step index fiber. As you can see in the image above, that refractive index of the core is n1 and that of cladding is n2. Since it is the step index fiber, therefore the refractive index of the core is constant (n1), and does not change as we move away from the axis of the core, within the core. But as we reach to the core-cladding interface, the refractive index inside the cladding changes suddenly to n2.
Since it makes sudden (step) change in the refractive index at the core-cladding interface. This is the reason, why it is called as step index fiber and as it supports multiple modes, so called as multimode step index fiber.
Since refractive index of the core (n1) is more than the refractive index of the cladding (n2), therefore Total Internal Reflection (TIR) phenomenon takes place, as the light rays move from the denser medium to the rarer medium (core to cladding).
Single mode step index fiber
It is also a step index fiber, but due to its small diameter of the core (2-10 micrometre), it can support only single mode of light. Therefore this type of step index fiber is known as single mode step index fiber. You can see the image shown above, how a single mode of light is propagating through the core of The Optical Fiber. Since it is a type of step index fiber, therefore the refractive index of this optical fiber makes step (sudden) change at the core cladding interface. It is also clear from the plot given for the single mode step index fiber.
Comparison of multimode step index fiber and single mode step index fiber, on the basis of following parameters-
Diameter
Multimode step index fiber has larger diameter of the core (more than 50 micrometer).
Single mode step index fiber has smaller diameter (2-10 micrometres)
Number of modes
Propagation of multiple modes is possible in case of Multimode step index fiber.
Only single mode is present in single mode step index fiber.
Dispersion
Dispersion is high in case of Multimode step index fiber, due to differing group velocities of various modes.
Dispersion is low, which is due to broadening of the single pulse of the light in case of single mode step index fiber.
Bandwidth
Bandwidth is low multimode step index fiber.
Bandwidth is higher in single mode step index fiber.
Coupling
In case of multimode step index fibers, spatially incoherent optical sources (LEDs), can be coupled easily and efficiently due to its large diameter. Due to large numerical aperture (NA), easy coupling is possible with optical sources.
While in single mode step index fibers, coupling is not easy due to smaller diameter. Since it has smaller.
Tolerance requirements on optical fiber connectors are higher in case of single mode step index fibers.
Visit My BLOG for more information
https://www.engineeringmadeeasypro.com/
PLAYLISTS on different Topics:
Electronics and Communication (ECE) Lecture Videos (GATE and IES)
Electronics and Communication (ECE) L...
Optical Fiber Communication
Optical Fiber Communication
Optical Fiber Communication in HINDI Videos
Optical Fiber Communication in HINDI ...
#OpticalFiberCommunication #StepIndexOpticalFiber #SingleModeAndMultimode #OpticalFiber #FiberCable #FiberOptics #OpticalFibre #OpticalCable #EngineeringMadeEasy
7 سال پیش
در تاریخ 1396/06/03 منتشر شده
است.
77,703
بـار بازدید شده