Applied Physics I: Chapter 9: Applied Optics - Fiber Optics
Principle and propagation of light in optical fiber
The principle of optical fiber communication is Total Internal Reflection (TIR).
PRINCIPLE AND
PROPAGATION OF LIGHT IN OPTICAL FIBER
For
optical fibers, the process of propagation of light (optical signal) is simple,
because once the light enters the fiber, the rays do not encounter any new
surfaces, but repeatedly they hit the same surface. The reason of confining the
light beam inside the fibers is the total internal reflection. (TIR).
Even
for a bent fiber, the light guidance takes place by multiple total internal
reflection all over the length of the fiber as shown in Fig.9.3.
Principle
The
principle of optical fiber communication is Total Internal Reflection (TIR).
Total
Internal Reflection
The
phenomenon of Total Internal Reflection takes place when it satisfies the
following two conditions.
Condition 1.
Light should travel from denser medium to rarer medium
i.e.
n1 > n2
Where
n1
= refractive index of core
n2
= refractive index of cladding
Condition 2.
The angle of incidence on core should be greater than the critical angle.
i.e.
ϕ > ϕc
Where
ϕ
- angle of incidence
ϕc - critical angle
Propagation
Phenomenon
Let
the light ray traverse (passes) from denser medium to rarer medium.
Case (i)
when ϕ < ϕc, the ray is refracted into the rarer medium as shown
in Fig.9.4.
Case (ii)
when ϕ = ϕc, the ray traverses along the interface as shown in
Fig.9.5, so that the angle of refraction is 90o. This angle (ϕc)
is called as critical angle.
Case (iii)
when ϕ > ϕc, the ray is totally reflected back (internally) into
the denser medium itself as shown in Fig.9.6 from Snell's Law (The maximum
angle for Total Internal Reflection ϕc).
n1sin
θc = n2sin 90º
sin
θc = n2 / n1
Since
sin90° = 1, we have
θc = sin‒1
( n2 / n1)
Applied Physics I: Chapter 9: Applied Optics - Fiber Optics : Tag: Applied Physics : - Principle and propagation of light in optical fiber
Applied Physics I: Chapter 9: Applied Optics - Fiber Optics
Under Subject
Applied Physics I
PH25C01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Related Subjects
English Essentials I
EN25C01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
தமிழர் மரபு - Heritage of Tamils
UC25H01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Applied Calculus
MA25C01 Maths 1 M1 - 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Applied Physics I
PH25C01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Applied Chemistry I
CY25C01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Makerspace
ME25C04 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Computer Programming C
CS25C01 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Computer Programming Python
CS25C02 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Fundamentals of Electrical and Electronics Engineering
EE25C03 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Introduction to Mechanical Engineering
ME25C03 1st Semester | 2025 Regulation | 1st Semester 2025 Regulation
Introduction to Civil Engineering
CE25C01 1st Semester Civil Department | 2025 Regulation | 1st Semester 2025 Regulation
Essentials of Computing
CS25C03 1st Semester - AID CSE IT Department | 2025 Regulation | 1st Semester 2025 Regulation
Applied Physics I Laboratory
PH25C01 1st Semester practical Laboratory Manual | 2025 Regulation | 1st Semester Laboratory 2025 Regulation
Applied Chemistry I Laboratory
CY25C01 1st Semester practical Laboratory Manual | 2025 Regulation | 1st Semester Laboratory 2025 Regulation
Computer Programming C Laboratory
CS25C01 1st Semester practical Laboratory Manual | 2025 Regulation | 1st Semester Laboratory 2025 Regulation
Computer Programming Python Laboratory
CS25C02 1st Semester practical Laboratory Manual | 2025 Regulation | 1st Semester Laboratory 2025 Regulation
Engineering Drawing
ME25C01 EEE Mech Dept | 2025 Regulation | 2nd Semester 2025 Regulation
Basic Electronics and Electrical Engineering
EE25C04 1st Semester ECE Dept | 2025 Regulation | 2nd Semester 2025 Regulation