16: Fibre optics and holography

Example number 16.1, Page number 306

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

#Variable declaration
n2=1.4;    #refractive index of cladding
n1=1.43;   #refractive index of core

#Calculation
costhetac=n2/n1;  
thetac=math.acos(costhetac);     #propagation angle(radian)
thetac=thetac*180/math.pi;    #propagation angle(degrees)
NA=math.sqrt(n1**2-n2**2);   #numerical aperture
thetaa=math.asin(NA);    #angle(radian)
thetaa=thetaa*180/math.pi;    #angle(degrees)
thetaa=2*thetaa;    #acceptance angle(degrees)

#Result
print "propagation angle is",round(thetac,1),"degrees"
print "numerical aperture is",round(NA,4)
print "acceptance angle is",round(thetaa,2),"degrees"

propagation angle is 11.8 degrees
numerical aperture is 0.2914
acceptance angle is 33.88 degrees

Example number 16.3, Page number 311

In [10]:
#importing modules
import math
from __future__ import division

#Variable declaration
z=30;    #length of optical fibre(km)
alpha=0.8;    #fibre loss(dB/km)
Pi=200;   #input power(micro W)

#Calculation
a=alpha*z/10;
b=10**a;
P0=Pi/b;    #output power(micro W)

#Result
print "output power is",round(P0,3),"micro W"

output power is 0.796 micro W