# 16: Fibre optics and holography¶

## Example number 16.1, Page number 306¶

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

#Variable declaration
n1=1.43;   #refractive index of core

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