# Chapter 3: Fiber optic technology¶

## Example 3.1 , Page no:38¶

In :
import math
from __future__ import division

#initialisation of variables
PL=1; #length of preform in m
PD=25e-3; #daimeter of preform in m
OD=125e-6;  #outer daimeter of optical fiber in m

#CALCULATIONS
V=3.14*((PD/2)**2)*PL;  #volume of Preform cylinder in m^3
L=V/(3.14*((OD)**2));  #Length of optical fiber in m

#RESULTS
print"Length of optical fiber=",L/1e3,"KM";  #division by 1e3 to convert unit from m to Km

Length of optical fiber= 10.0 KM


## Example 3.2 , Page no:41¶

In :
import math
from __future__ import division

#initialisation of variables
NA1=0.2;  #numerical apperture of fiber 1
NA2=0.1;  #numerical apperture of fiber 2
D1=12;  #core daimeter of fiber 1 in um
D2=6;  #core daimeter of fiber 2 in um

#CALCULATIONS
Losses=20*math.log10(NA1/NA2)+20*math.log10(D1/D2);  #total fiber to fiber coupling losses due to NA mismatch and size mismatch

#RESULTS
print"total losses=",round(Losses,5),"db";

total losses= 12.0412 db