# Chapter 12: Fiber Optics¶

## Example 12.1, Page number 12.6¶

In :
import math

#Variable declaration
n1 = 1.55  #refractive inde of core
n2 = 1.50  #refractive index of cladding

#Calculation
NA = math.sqrt(n1**2-n2**2)

#Result
print "Numerical Aperture =",round(NA,3)

Numerical Aperture = 0.391


## Example 12.2, Page number 12.6¶

In :
import math

#Variable declaration
n1 = 1.563  #refractive inde of core
n2 = 1.498  #refractive index of cladding

#Calculation
NA = math.sqrt(n1**2-n2**2)
alpha_i = math.degrees(math.asin(NA))

#Result
print "Angle of acceptance =",round(alpha_i,2),"degrees"

Angle of acceptance = 26.49 degrees


## Example 12.3, Page number 12.6¶

In :
import math

#Variable declaration
NA = 0.39       #numerical aperture
delta_n = 0.05  #differnce between refractive indices of core & cladding

#Calculaations
n1 = NA/math.sqrt(2*delta_n)

#Result
print "Refractive index of core =",round(n1,4)

Refractive index of core = 1.2333


## Example 12.4, Page number 12.7¶

In :
#Variable declaration
n1 = 1.563  #refractive inde of core
n2 = 1.498  #refractive index of cladding

#Calculation
delta = (n1-n2)/n1

#Result
print "Fractional index change for the given fiber is",round(delta,4)

Fractional index change for the given fiber is 0.0416


## Example 12.5, Page number 12.7¶

In :
import math

#Variable declaration
n1 = 1.48  #refractive inde of core
n2 = 1.45  #refractive index of cladding

#Calculations
NA = math.sqrt(n1**2-n2**2)
alpha_i = math.degrees(math.asin(NA))

#Result
print "Numerical aperture =",round(NA,4)
print "Angle of acceptance =",round(alpha_i,2),"degrees"

Numerical aperture = 0.2965
Angle of acceptance = 17.25 degrees


## Example 12.6, Page number 12.14¶

In :
import math

#Variable declaration
Pout = 40.     #output power(mW)
Pin = 100.     #input power(mW)

#Calculation
A = -10*math.log10(Pout/Pin)  #Attenuation(dB)

#Result
print "Attenuation =",round(A,2),"dB"

Attenuation = 3.98 dB