# Chapter 2: Optical fibers: Structures, Waveguiding, and Fabrication¶

## Example 2.1, Page Number: 37¶

In [10]:
import math

#variable declaration
n1 = 1.48                           #core refractive index for glass n1
n2 = 1.00                           #core refractive index for air n2

#calculation
phic = math.asin(n2/n1)             #Interflaction reflaction angle(degree)

#result
print  "Total Interflaction reflaction angle = ",round(phic*57.3,1),"degree"

Total Interflaction reflaction angle =  42.5 degree


## Example 2.2, Page Number: 45¶

In [11]:
import math

#variable declaration
n1=1.48                              #core refractive index
n2=1.46                              #cladding refractive index

#calculation
phiC=math.degrees(math.asin(n2/n1))       #critical angle (degree)
NA=math.sqrt((n1*n1)-(n2*n2))             #numerical apperture
phiO=math.degrees(math.asin(NA))          #maximum entrance angle (degree)

#result
print "Critical angle =" ,round(phiC,1),"degree"
print "Numerical apperture =" ,round(NA,3)
print "Acceptance angle =" ,int(phiO),"degree"

Critical angle = 80.6 degree
Numerical apperture = 0.242
Acceptance angle = 14 degree


## Example 2.3 , Page Number: 58¶

In [12]:
import math

#variable declaration
V=26.6                          #normalized frequency
lamda=1300*1e-9                 #wavelength(nm)

#caculation
NA=(V*lamda)/(2*math.pi*a)      #numerical aperture

#result
print "Numerical aperture =",round(NA,2)

Numerical aperture = 0.22


## Example 2.4 , Page Number: 62¶

In [13]:
import math

#variable declaration
V2 = 22                      #normalized frequency2
V1=39                        #normalized frequency1
p=1.4

#calculation
M1=(V1**2)/2                         #modes in fiber1
M2=V2**2/2                           #modes in fiber2

#result
print 'case1 : Total number of modes',M1
print 'case1 : Percent age of power propagates in the cladding',int(Pcladd_P1 *100)
print 'case2 : Total number of modes',M2
print 'case2 : Percent age of power propagates in the cladding',int(round(Pcladd_P2 *100,0))

case1 : Total number of modes 760
case1 : Percent age of power propagates in the cladding 5
case2 : Total number of modes 242
case2 : Percent age of power propagates in the cladding 9


## Example 2.5 , Page Number: 65¶

In [15]:
import math

#variable declaration
lamda=1300*1e-9               #wavelength(nm)
Lp=8*1e-2                     #beat length(cm)

#calculation
Bf=lamda/Lp                   #modal birefringence
bita=(2*math.pi)/Lp           #birefringence(1/m)

#result
print "Modal birefringence =",round(Bf,7)
print "Birefringence Bita =",bita,"1/m"

Modal birefringence = 1.62e-05
Birefringence Bita = 78.5398163397 1/m