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{
"metadata": {
"name": "Chapter_6"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": "Chapter 6 - Optical sources 1: the laser\n"
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.1, page 301"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\nc=2.998*10**8 #speed of light in m/s\nh=0.5*10**-6 #operating wavelength in um\nt=1000 #tempreture in K\n\n#Calculation\nf=c/h #operating frequency\nr=1/math.exp((6.626*10**-34*f)/(1.381*10**-23*t)) #ratio\n\n#Result\nprint'Ratio = %.1f x 10^-13 '%(r*10**13)\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "Ratio = 3.2 x 10^-13 \n"
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.2, page 306"
},
{
"cell_type": "code",
"collapsed": false,
"input": "#Variable declaration\nn=1.78 #refractive index\nL=0.04 #length in meter\nh=0.55*10**-6 #peak emission wavelength in um\nc=2.998*10**8 #speed of light in meter\n\n#Calculation\nq=2*n*L/h #no of longitudinal modes\nsf=c/(2*n*L) #frequency separation modes\n\n#Result\nprint'No of longitudinal modes = %.1f x 10^5'%(q/10**5)\nprint'Frequency separation modes = %.1f GHz'%(sf/10**9)\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "No of longitudinal modes = 2.6 x 10^5\nFrequency separation modes = 2.1 GHz\n"
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.3, page 308"
},
{
"cell_type": "code",
"collapsed": false,
"input": "#Variable declaration\na=30 #active cavity losses\nL=0.06 #length in meter\nr=0.3 #reflectivity\n\n\n#Calculation\ngm=a+(1/L)+(1/r) #laser gain coefficient\n\n\n#Result\nprint'Laser gain coefficient = %.1f cm^-1'%gm",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "Laser gain coefficient = 50.0 cm^-1\n"
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.4, page 315"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\nBt1=7.21*10**-10 #recombination coefficient of GaAs\nBt2=1.79*10**-15 #recombination coefficient of Si\nN=10**18 #hole concentration \n\n#Calculation\ntr1=(Bt1*N)**-1 #radiative carrier lifetime of GaAs\ntr2=(Bt2*N)**-1 #radiative carrier lifetime of Si\n\n#Result\nprint'Radiative carrier lifetime of silicon = %.2f ms'%(tr2*1000)\nprint'Radiative carrier lifetime of gallium arsenide = %.2f ns'%(tr1*10**9)",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "Radiative carrier lifetime of silicon = 0.56 ms\nRadiative carrier lifetime of gallium arsenide = 1.39 ns\n"
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.5, page 322"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\nn=3.6 #refractive index\nB=21*10**-3 #gain factor\na=10 #loss coefficient per cm\nL=250*10**-4 #optical cavity length\nw=100*10**-4 #optical cavity width\n\n#Calculation\nr=((n-1)/(n+1))**2 #reflectivity\njth=(1/B)*(a+math.log(1/r)/L) #threshold current density\narea=L*w #area\nith=jth*area #threshold current\n \n#Result\nprint'Threshold current = %.1f mA'%(ith*1000)",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "Threshold current = 662.4 mA\n"
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.6, page 330"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\nnt=0.18 #total efficiency\nE=1.43 #bandgap energy\nV=2.5 #voltage\n\n\n#Calculation\nnep=nt*(E/V)*100 #external power efficiency\n\n#Result\nprint'External power efficiency = %d percent'%nep",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "External power efficiency = 10 percent\n"
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.7, page 352"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\nt1=20+273 #tempreture 20 \u00b0C convert to kelvin\nt2=80+273 #tempreture 80 \u00b0C convert to kelvin\nL1=160 #tempreture 160K\nL2=55 #tempreture 55K\n\n#Calculation\na=t1*L1**-1 \nb=t2*L1**-1\nc=t1*L2**-1\nd=t2*L2**-1\nJa1=math.exp(a) #For the AlGaAs device\nJa2=math.exp(b) #For the AlGaAs device\nJa=Ja2/Ja1 #ratio of the current densities\nJb1=math.exp(c) #For the InGaAsP device\nJb2=math.exp(d) #For the InGaAsP device\nJb=Jb2/Jb1 #ratio of the current densities\n\n#Result\nprint'Threshold current density at 20 \u00b0C = %.2f'%Ja\nprint' at 80 \u00b0C = %.2f' %Jb\n",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "Threshold current density at 20 \u00b0C = 1.45\n at 80 \u00b0C = 2.98\n"
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": "Example 6.8, page 359"
},
{
"cell_type": "code",
"collapsed": false,
"input": "import math\n\n#Variable declaration\ns=10**-15 #RIN value \nf=100*10**6 #bandwidth\ne=1.602*10**-19 #1 electron volt\nn=0.6 #quantum efficiency\nh=1.55*10**-6 #wavelength in um\npe=2*10**-3 #power incident\nB=100*10**6 #bandwidth\nh1=6.626*10**-34 #plancks constant\nc=2.998*10**8 #speed of light\n\n#Calculation\nsr=s*f \nrin=math.sqrt(sr) #RMS value of power fluctuation\nirn=e*n*h*rin*pe*math.sqrt(B)*10**-4/(h1*c) #RMS noise current\n\n#Result\nprint'(a) RMS value of power fluctuation = %.2f x 10^-4 W'%(rin*10**4)\nprint'(b) RMS noise current = %.2f x 10^-7 A'%(irn*10**7)",
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": "(a) RMS value of power fluctuation = 3.16 x 10^-4 W\n(b) RMS noise current = 4.74 x 10^-7 A\n"
}
],
"prompt_number": 8
}
],
"metadata": {}
}
]
}
|
