# Chapter 10 : Optical amplification, wavelength conversion and regeneration¶

## Example 10.1, page 555¶

In [1]:
import math

#Variable declaration
h=1.5*10**-6                         #peak gain wavelength
delt=10**-9                          #mode spacing
l=300*10**-6                        #length
c=2.998*10**8                        #speed of light
r=0.09                              #facet reflectivities
gs=3.020

#Calculation
n=(h**2)/(2*delt*l)                       #refractive index
a=c/(math.pi*n*l)
d=1-(math.sqrt(r)*gs)
f=2*math.sqrt(math.sqrt(r)*gs)
B=a*math.asin(d/f)                        #spectral bandwidth
#Result
print'Refractive index of a medium = %.2f'%n
print'3dB spectral bandwidth = %.1f GHz'%(B*10**-9)

Refractive index of a medium = 3.75
3dB spectral bandwidth = 4.2 GHz


## Example 10.3, page 562¶

In [2]:
import math

#Variable declaration
gs=30                                #gain in dB
g=200                                #net gain
loge=0.434                           #log(e)
gs1=1000
m=2.2                                #mode no
nsp=4                                #spontaneous emission factor
h1=6.626*10**-34                     #plancks constant
f=1.94*10**14
B=1.0*10**12                         #bandwidth

#Calculation
L=gs/(10*g*loge)                       #length of the device
P=m*nsp*(gs1-1)*h1*f*B                 #noise power spectral density

#Result
print'(a) Length of the device = %.2f mm'%(L*10**3)
print'(b) Noise power spectral density = %.2f mW'%(P*10**3)

(a) Length of the device = 34.56 mm
(b) Noise power spectral density = 1.13 mW


## Example 10.4, page 580¶

In [3]:
import math

#Variable declaration
Gp=62.2                                           #parametric peak gain in dB
log=10*math.log10(0.25)
Pp=1.4                                            #signal power in watt
L=500                                             #length in meter
log2=20*math.log10(2.7182818284)

#Calculation
y=(Gp-log)/(Pp*L*log2)                              #fiber nonlinear coefficient
Gp2=10*math.log10((y*Pp*L)**2)                      #parametric gain

#Result
print'(a) Fiber nonlinear coefficient = %.2f x 10^-3 W^-1 km^-1'%(y*1000)
print'(b) Quadratic gain, Gp = %.2f dB'%(Gp2)

(a) Fiber nonlinear coefficient = 11.22 x 10^-3 W^-1 km^-1
(b) Quadratic gain, Gp = 17.90 dB


## Example 10.5, page 589¶

In [4]:
import math

#Variable declaration
pt=0.5*10**-3                                #input signal power
dpt=0.01*10**-6                              #input signal power variation
h=1.55*10**-6                                #signal wavelength
a=-1                                         #linewidth enhancement factor
dn=-1.2*10**-26                              #differential refractive index

#Calculation
delt=(-a*dpt)/(4*math.pi*pt)                  #frequency chirp
dg=(4*math.pi*dn)/(h*a)                       #differential gain

#Result
print'(a) Frequency chirp variation = %.2f MHz'%(delt*10**6)
print'(b) Differential gain = %.2f x10^-20 m^2'%(dg*10**20)

(a) Frequency chirp variation = 1.59 MHz
(b) Differential gain = 9.73 x10^-20 m^2