# Ch-3 Electroluminescent Sources¶

## Example 3.1 Page no 80¶

In [1]:
from __future__ import division
from math import log
#Calculation of barrier potential
#Given data
p=5#                        # Resistivity of p-region
n=2#                        # Resistivity of n-region
mu=3900#
k=0.026#                    #Boltzmann constant
ni=2.5*10**13#              #Density of the electron hole pair
e=1.6*10**-19#              #charge of electron

#Barrier potential calculation
r0=(1/p)#          # Reflection at the fiber air interface
r1=(1/n)#
m=r1/(mu*e)#
p=6.5*10**14#       #Density of hole in p -region
Vb=k*log(p*m/ni**2)#
print "Barrier potential = %0.3f V"%Vb

# The answers vary due to round off error

Barrier potential = 0.175 V


## Example 3.15 Page no 484¶

In [2]:
# Calculation of external efficiency
#Given data
ne1=0.20#       #Total efficiency
V=3#            # Voltage applied
Eg=1.43#        # Bandgap energy

# External efficiency
ne=(ne1*Eg/V)*100#
print "External efficiency of the device = %0.1f %% "%(ne)#

External efficiency of the device = 9.5 %


## Example 3.16 Page no 484¶

In [3]:
from math import exp
#  Calculation of ratio of threshold current densities
# Given data
To1=160#                     # Device temperature
To2=55#                      # Device temperature
T1=293#
T2=353#
J81=exp(T1/To1)#            # Threshold current density
J21=exp(T2/To1)#
J82=exp(T1/To2)##
J22=exp(T2/To2)##
cd1=J21/J81#               # Ratio of threshold current densities
cd2=J22/J82#

print"Ratio of threshold current densities= %0.2f  "%(cd1)
print"Ratio of threshold current densities= %0.2f  "%(cd2)

Ratio of threshold current densities= 1.45
Ratio of threshold current densities= 2.98


## Example 3.17 Page no 484¶

In [4]:
#Computation of conversion efficiency
#Given data
i=10*10**-6#            # Device current
p=5#                  # Electrical power
op=50 *10**-6#         # Optical power
ip=5*10*10**-3#        # Input power

#Conversion efficiency
c=op/ip*100#
print "Conversion efficiency = %0.1f %% "%(c)

Conversion efficiency = 0.1 %


## Example 3.18 Page no 485¶

In [5]:
# Calculation of total power emitted
#Given data
r=0.7#            # Emissivity
r0=5.67*10**-8#    # Stephen's constant
A=10**-4#          # Surface area
T=2000#           # Temperature

# Total power emitted
P=r*r0*A*T**4#

print"Total power emitted = %0.1f Watts "%P

Total power emitted = 63.5 Watts


## Example 3.19 Page no 485¶

In [6]:
# Computation of total energy
#Given data
h=6.63*10**-34#        # Planck constant
v=5*10**14#            # Bandgap frequency of laser
N=10**24#              # Population inversion density
V=10**-5#              # Volume of laser medium

# Total energy
E=(1/2)*h*v*(N)*V#

print "Total energy = %0.1f J "%E

Total energy = 1.7 J


## Example 3.20 Page no 485¶

In [7]:
# Computation of pulse power
# Given data
L=0.1#               # Length of laser
R=0.8#               # Mirror reflectance of end mirror
E=1.7#               # Laser pulse energy
c=3*10**8#            # Velocity of light
t=L/((1-R)*c)#         # Cavity life time

# Pulse power
p=E/t#

print"Pulse power = %0.0f W "%p

Pulse power = 1020000000 W