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{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"# 12: Lasers"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 1, Page number 12.30"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"relative population in laser transition levels is 1.081 *10**30\n",
"answer given in the book is wrong\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"h=6.626*10**-34; #plancks constant(J s)\n",
"c=3*10**8; #velocity of light(m/s)\n",
"lamda=6943*10**-10; #wavelength of emission(m)\n",
"k=1.38*10**-23; #boltzmann constant\n",
"T=300; #temperature(K)\n",
"\n",
"#Calculation\n",
"new=c/lamda; #frequency(Hz)\n",
"x=h*new/(k*T);\n",
"N1byN2=math.exp(x); #relative population in laser transition levels\n",
"\n",
"#Result\n",
"print \"relative population in laser transition levels is\",round(N1byN2/10**30,3),\"*10**30\"\n",
"print \"answer given in the book is wrong\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 2, Page number 12.31"
]
},
{
"cell_type": "code",
"execution_count": 10,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"number of photons emitted is 7.323 *10**15 photons/second\n",
"power density is 2.3 kW/m**2\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"h=6.626*10**-34; #plancks constant(J s)\n",
"P=2.3*10**-3; #output power(W)\n",
"t=1; #time(sec)\n",
"new=4.74*10**14; #frequency(Hz)\n",
"s=1*10**-6; #spot area(m**2)\n",
"\n",
"#Calculation\n",
"n=P*t/(h*new); #number of photons emitted in each second \n",
"Pd=P/s; #power density(W/m**2)\n",
"\n",
"#Result\n",
"print \"number of photons emitted is\",round(n/10**15,3),\"*10**15 photons/second\"\n",
"print \"power density is\",Pd/10**3,\"kW/m**2\""
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## Example number 3, Page number 12.31"
]
},
{
"cell_type": "code",
"execution_count": 2,
"metadata": {
"collapsed": false
},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"wavelength of emission is 8628 angstrom\n"
]
}
],
"source": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"h=6.626*10**-34; #plancks constant(J s)\n",
"c=3*10**8; #velocity of light(m/s)\n",
"Eg=1.44*1.6*10**-19; #band gap(J)\n",
"\n",
"#Calculation\n",
"lamda=h*c/Eg; #wavelength of emission(m)\n",
"\n",
"#Result\n",
"print \"wavelength of emission is\",int(round(lamda*10**10)),\"angstrom\""
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 2",
"language": "python",
"name": "python2"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 2
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython2",
"version": "2.7.11"
}
},
"nbformat": 4,
"nbformat_minor": 0
}
|
