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{
"metadata": {
"name": "",
"signature": "sha256:ac80f9dfe1725f11a5d4ce0fbda5ffed825d99c680f116629e5e3fcb8b69c198"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Lasers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 2.1, Page number 52"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#To calculate the relative population \n",
"\n",
"#importing modules\n",
"import math\n",
"\n",
"#Variable declaration\n",
"lamda = 590; #wavelength(nm)\n",
"h = 6.625*10**-34; #planck's constant\n",
"c = 3*10**8; #velocity of light(m/s)\n",
"k = 1.38*10**-23; #boltzmann's constant\n",
"T = 523; #temperature(Kelvin)\n",
"\n",
"#Calculation\n",
"lamda = lamda*10**-9; #wavelength(m) \n",
"#n1byn2 = math.exp(-(E2-E1)/(k*T))\n",
"#but E2-E1 = h*new and new = c/lamda\n",
"#therefore n1byn2 = math.exp(-h*c/(lamda*k*T))\n",
"n1byn2 = math.exp(-h*c/(lamda*k*T));\n",
"\n",
"#Result\n",
"print \"relative population of Na atoms is\",n1byn2"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"relative population of Na atoms is 5.36748316686e-21\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 2.2, Page number 53"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#To calculate the ratio of stimulated to spontaneous emission \n",
"\n",
"#importing modules\n",
"import math\n",
"\n",
"#Variable declaration\n",
"lamda = 590; #wavelength(nm)\n",
"h = 6.625*10**-34; #planck's constant\n",
"c = 3*10**8; #velocity of light(m/s)\n",
"k = 1.38*10**-23; #boltzmann's constant\n",
"T = 523; #temperature(Kelvin)\n",
"\n",
"#Calculation\n",
"lamda = lamda*10**-9; #wavelength(m) \n",
"#n21dashbyn21 = 1/(math.exp(h*new/(k*T))-1)\n",
"#but new = c/lamda\n",
"#therefore n21dashbyn21 = 1/(math.exp(h*c/(lamda*k*T))-1)\n",
"A = math.exp(h*c/(lamda*k*T))-1;\n",
"n21dashbyn21 = 1/A; \n",
"\n",
"#Result\n",
"print \"ratio of stimulated to spontaneous emission is\",n21dashbyn21\n",
"print \"answer given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"ratio of stimulated to spontaneous emission is 5.36748316686e-21\n",
"answer given in the book is wrong\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 2.3, Page number 53"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#To calculate the number of photons emitted \n",
"\n",
"#importing modules\n",
"import math\n",
"\n",
"#Variable declaration\n",
"lamda = 632.8; #wavelength of laser(nm)\n",
"h = 6.625*10**-34; #planck's constant\n",
"c = 3*10**8; #velocity of light(m/s)\n",
"p = 3.147; #output power(mW)\n",
"\n",
"#Calculation\n",
"p = p*10**-3; #output power(W)\n",
"lamda = lamda*10**-9; #wavelength(m) \n",
"new = c/lamda; #frequency(Hz)\n",
"E = h*new; #energy of each photon(J)\n",
"Em = p*60; #energy emitted per minute(J/min)\n",
"N = Em/E; #number of photons emitted per second\n",
"\n",
"#Result\n",
"print \"number of photons emitted per second is\",N"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"number of photons emitted per second is 6.01183879245e+17\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "code",
"collapsed": false,
"input": [],
"language": "python",
"metadata": {},
"outputs": []
}
],
"metadata": {}
}
]
}
|
