Chapter 20 : Optical communication

Example 20.1 Page No : 616

In [2]:
import math 

#page no 616
#prob no. 20.1

# Variables
lembda = 1300.*10**-9;   #wavwlength in m
c = 3*10**8;            #speed of light in m/s

# Calculations
f = c/lembda           #in Hz

# Results
print 'frequency of laser is ,f = %.0f  THz'%(f*10**-12);

frequency of laser is ,f = 231  THz

Example 20.2 Page No : 619

In [3]:
import math 

# Variables
theta_i = 30;    #degree
ni = 1.00;       #incident refraction index
nr = 1.52;       #refeacted ray refraction index

# Calculations
theta_r = math.asin(ni/nr*math.sin(theta_i*math.pi/180));    #in radians

# Results
print 'angle of refraction is %.2f  degree'%(theta_r*180/math.pi);

angle of refraction is 19.20  degree

Example 20.3 Page No : 620

In [4]:
import math 

# Variables
theta_r = 90.;    #degree
ni = 1.52;       #refraction index for crown glass
nr = 1.00;       #refraction index for air

# Calculations
theta_i = math.asin(nr/ni*math.sin(theta_r*math.pi/180));    #in radians

# Results
print 'critical angle is %.2f  degree'%(theta_i*180/math.pi);
#misprinted theta_r in the text
#values are raunded up in the text

critical angle is 41.14  degree

Example 20.4 Page No : 624

In [5]:
# Variables
eta = .8;    #efficiency 
lembda = 850;  #nm

# Calculations
R = eta*lembda/1234;    #  A/W

# Results
print 'The responsivity of diode is R =  %.2f  A/W'%(R);

The responsivity of diode is R =  0.55  A/W

Example 20.5 Page No : 624

In [6]:
# Calculations
eta = .6;    #efficiency 
lembda = 1310;  #nm

# Calculations
R = eta*lembda/1234;    #  A/W

# Results
print 'The responsivity of diode is R =  %.2f  A/W'%(R);

The responsivity of diode is R =  0.64  A/W

Example 20.6 Page No : 627

In [7]:
# Calculations
L = .4*.8;    #loss in dB

# Results
print 'The loss usong this cable is L =  %.2f  dB'%(L);

The loss usong this cable is L =  0.32  dB

Example 20.7 Page No : 627

In [8]:
# Calculations
L = 2.7*.8;    #loss in dB

# Results
print 'The loss usong multimode cable is L =  %.2f  dB'%(L);

The loss usong multimode cable is L =  2.16  dB