Optical Fibers

What are the conditions for optical fibers ?

• n1 > n2

• Total internal reflection

What is Numerical apparatus of step index ?

Aise ray jisese Reflective index ho thats called Numerical apparatus of step index

What is Numerical apparatus of step index ? ( Official )

The ray by which reflective index takes place is known as Numerical Apparatus of step index

Diagram of Numerical apparatus of step index !

Snell’s law for angle of incidence ?

• Derivation

• I max = sin!^-1 n

What is acceptance angle ?

What is under this angle will get accepted

In which condition there will be loss in system ?

Pout < Pin

In which condition there will be no loss in system ?

Pout > Pin

What is attenuation ?

loss in system is attenuation

What is the formula of attenuation ?

What is attenuation constant ?

α (alpha)

What is the unit of attenuation ?

Decibals (dB)

If Pout = ½ pin then

α = 10log2

What are the types of loss ?

• Absorption loss

• Scattering loss

• Bending loss

What is absorption loss ?

Loss due to absorption

What is Scattering loss ?

Loss due to scattering

What is Bending loss ?

Loss when bending happen

What is scattering ?

They occurs when the mode of propagation is changed such that some of the optical energy leaves the fiber

• It occur due to imperfection in fiber

What are the examples of Scattering ?

• Silica + B2O3 —> n (down)

• Silica + GeO2 / P2O5 —> n ( up ) core

Scattering may happen due to ?

dust

Rayleigh is indirectly proportional too ?

Rayleigh scattering is inversely proportional to the fourth power of the wavelength (λ^4).

Fiber should be ———- while making optical finer bcz it cause that

Minimize

When absorption takes place ?

Absorption takes place when the electronic transistors are excited within the material and then followed by non - radioactive relaxation process

What are the types of absorption

• Intrinsic material absorption loss

  • In UV range

  • In IR range

• Absorption due to impurity ions

In UV range when absorption take place ?

The absorption occurs when light photons contain enough energy to excite electron from valance band to a conduction band

In IR region when absorption takes place ?

The absorption are caused molecular vibration .

• The vibration occurs due to oxide Bonds

What is the peak absorption is ?

8 UM

What is the peak absorption of Si - O ?

9Um

What is the peak absorption of Ge - O ?

11Um

What is the peak absorption of P - O ?

8Um

What is the peak absorption of B - O ?

7.3Um

Absorption due to impurity ions

Hydroxyl ions

Hydroxyl ions

The absorption caused by hydroxyl ions arises from the basi stretching vibration of ( O - H Bond )