13: Fiber Optics

Example number 13.1, Page number 13.5

In [2]:
#importing modules
import math
from __future__ import division

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

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

#Result
print "numerical aperture is",round(NA,3)

numerical aperture is 0.391

Example number 13.2, Page number 13.6

In [8]:
#importing modules
import math
from __future__ import division

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

#Calculation
NA=math.sqrt(n1**2-n2**2);    #numerical aperture
alpha_i=math.asin(NA);      #angle of acceptance(radian)
alpha_i=(alpha_i*180/math.pi);    #angle(degrees)
alpha_id=int(alpha_i);
alpha_im=60*(alpha_i-alpha_id);

#Result
print "angle of acceptance is",alpha_id,"degrees",round(alpha_im,1),"minutes"
print "answer varies due to rounding off errors"

angle of acceptance is 26 degrees 29.5 minutes
answer varies due to rounding off errors

Example number 13.3, Page number 13.6

In [13]:
#importing modules
import math
from __future__ import division

#Variable declaration
NA=0.39;       #numerical aperture
delta=0.05;    #difference of indices

#Calculation
n1=NA/math.sqrt(2*delta);     #refractive index of core

#Result
print "refractive index of core is",round(n1,4)
print "answer varies due to rounding off errors"

refractive index of core is 1.2333
answer varies due to rounding off errors

Example number 13.4, Page number 13.7

In [15]:
#importing modules
import math
from __future__ import division

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

#Calculation
delta=(n1-n2)/n1;    #fractional index change

#Result
print "fractional index change is",round(delta,4)

fractional index change is 0.0416

Example number 13.5, Page number 13.7

In [19]:
#importing modules
import math
from __future__ import division

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

#Calculation
NA=math.sqrt(n1**2-n2**2);    #numerical aperture
alpha_i=math.asin(NA);      #angle of acceptance(radian)
alpha_i=(alpha_i*180/math.pi);    #angle(degrees)
alpha_id=int(alpha_i);
alpha_im=60*(alpha_i-alpha_id);

#Result
print "numerical aperture is",round(NA,4)
print "angle of acceptance is",alpha_id,"degrees",round(alpha_im),"minutes"

numerical aperture is 0.2965
angle of acceptance is 17 degrees 15.0 minutes

Example number 13.6, Page number 13.14

In [22]:
#importing modules
import math
from __future__ import division

#Variable declaration
Pout=40;    #power(mW)
Pin=100;    #power(mW)

#Calculation
al=-10*math.log10(Pout/Pin);    #attenuation loss(dB)

#Result
print "attenuation loss is",round(al,2),"dB"

attenuation loss is 3.98 dB