{ "metadata": { "name": "Chapter 2(s)" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": "Chapter 2: Lasers" }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 1, Page No: 2.40" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Number of electron hole pairs\n\nimport math\n\n# Variable Declaration\nA = 4*10**-6; # Receiving area of photo detector\nI = 200; # Intensity in W/m^2\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 0.4*10**-6; # wavelength of light in m\n\n#Calculations\nv = c/lamda; # frequency\nNOP = I*A/(h*v) # number of photons\n\n#since each photon generates an electron hole pair, the number of photons is equal to number of electron hole pairs\n\n# Result\n\nprint 'Number of electron hole pairs = %3.2e '%NOP;\n", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Number of electron hole pairs = 1.61e+15 \n" } ], "prompt_number": 7 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 2, Page No:2.40" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Wavelength\n\nimport math\n\n# Variable Declaration\nEg = 2.8; # bandgap energy in eV\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nq = 1.602*10**-19; # charge of electron\n\n# Calculations\nE = Eg*q # eV to joules conversion\nlamda = h*c/E; # wavelength\n\n#Result\nprint 'wavelength = %3.1f' %(lamda*10**10), '\u00c5(Blue Colour)';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "wavelength = 4430.8 \u00c5(Blue Colour)\n" } ], "prompt_number": 11 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 3, Page No:2.41" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Energy bandgap\n\nimport math;\n\n# Variable Declaration\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 1.55*10**-6; # wavelength of light in m\nq = 1.6*10**-19; # charge of electron\n\n#Calculations\nEg = (h*c)/lamda; # band gap energy in joules\nE = Eg/q # bang gap energy in eV\n\n# Result\nprint 'Energy bandgap Eg = %3.4f'%E, 'eV';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Energy bandgap Eg = 0.8014 eV\n" } ], "prompt_number": 12 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 4, Page No:2.41" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Number of photons required to do one Joule of work\n\nimport math\n\n# Variable Declaration\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 4961*10**-10; # wavelength of light in m\n\n# Calculations\nE = (h*c)/lamda; # energy in joules\nN = 1/E\n\n# Result\nprint 'Number of photons required to do one Joule of work = %3.4e'%N,'/m^3';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Number of photons required to do one Joule of work = 2.4961e+18 /m^3\n" } ], "prompt_number": 14 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 5, Page No:2.41" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Wavelength Limit\n# import math\n\n# Variable Declaration\nE = 0.02; # ionisation energy in eV\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nq = 1.6*10**-19; # charge of electron\n\n# Calculations\n\nlamda = h*c/(E*q) # long wavelength limit in m\n\n# Result\n\nprint 'long wavelength limit = %3.3e' %lamda,' m';\n", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "long wavelength limit = 6.211e-05 m\n" } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Example 6, Page No:2.42" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Wavelength\n\nimport math;\n\n# Variable Declaration\nE = 1.44; # Bandgap energy in eV\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nq = 1.6*10**-19; # charge of electron\n\n# Calculations\n\nlamda = h*c/(E*q) # Wavelength of GaAs laser\n\n# Result\nprint 'Wavelength of GaAs laser = %3.1f'%(lamda*10**10),' \u00c5';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Wavelength of GaAs laser = 8626.3 \u00c5\n" } ], "prompt_number": 18 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 1, Page No:2.42" }, { "cell_type": "code", "collapsed": false, "input": "# Finding Energy of the first excited state\n\nimport math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 5890*10**-10; # wavelength of light in m\nq = 1.6*10**-19; # charge of electron\n\n\n# Calculations\nEg = (h*c)/lamda; # energy in joules\nE = Eg/q # energy in eV\n\n# Result\nprint 'Energy of the first excited state = %3.3f' %E,'eV';\n", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Energy of the first excited state = 2.109 eV\n" } ], "prompt_number": 21 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 2, Page No:2.43" }, { "cell_type": "code", "collapsed": false, "input": "# Finding The ratio between the stimulated emission and apontaneous emission\n\nimport math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 5890*10**-10; # wavelength of light in m\nk = 1.38*10**-23; # Boltzmann constant\nTc = 280 # Temperature in centigrades\n\n# Calculations\nT = Tc+273; # temperature in kelvin\nR = 1/((math.exp((h*c)/(k*T*lamda))) - 1); # ratio of stimulated emission to spontaneous emission\n\n# Result\nprint 'The ratio between the stimulated emission and apontaneous emission = %3.3e' %R;", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "The ratio between the stimulated emission and apontaneous emission = 6.264e-20\n" } ], "prompt_number": 24 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 3, Page No:2.43" }, { "cell_type": "code", "collapsed": false, "input": "# Finding The No. of Photons emitted per minute\n\nimport math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 6328*10**-10; # wavelength of He-Ne laser source in m\nq = 1.6*10**-19; # charge of electron\nP = 3*10**-3 # output power of the He-Ne source in watts or J/sec\n\n\n# Calculations\nv = c/lamda # frequency of the photon emitted by the laser beam\nE = h*v; # energy of a photon in joules\nPo = P*60; # conversion from J/sec to J/min\nN = Po/E; # No of photons emitted per minute \n\n# Result\nprint 'The No. of Photons emitted per minute = %3.3e' %N, 'photons/minute';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "The No. of Photons emitted per minute = 5.731e+17 photons/minute\n" } ], "prompt_number": 25 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 4, Page No:2.44" }, { "cell_type": "code", "collapsed": false, "input": "# Finding The No. of Photons emitted per hour\n\nimport math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 9.6*10**-6; # wavelength of CO2 laser source in m\nq = 1.6*10**-19; # charge of electron\nP = 10*10**3 # output power of the CO2 laser source in watts or J/sec\n\n\n# Calculations\nv = c/lamda # frequency of the photon emitted by the laser beam\nE = h*v; # energy of a photon in joules\nPo = P*60*60; # conversion fro J/sec to J/hour\nN = Po/E; # No of photons emitted per hour \n\n# Result\nprint 'The No. of Photons emitted per hour = %3.3e'%N,' photons/hour';\n", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "The No. of Photons emitted per hour = 1.739e+27 photons/hour\n" } ], "prompt_number": 26 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 5, Page No:2.45" }, { "cell_type": "code", "collapsed": false, "input": "import math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 10*10**-2; # wavelength for microwave region in m\nT = 300 # Temperature in Kelvin\nKb = 1.38*10**-23 # Boltzmann constant\n\n# Calculations\n# let R = Rsp/Rst \nR = math.exp((h*c)/(lamda*Kb*T)) - 1 ; # ratio of spontaneous to stimulated emission\nif R<1:\n print 'Since the spontaneous emission is lesser than stimulated emission \\n hence MASER action is possible at thermal equilibrium'", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Since the spontaneous emission is lesser than stimulated emission \n hence MASER action is possible at thermal equilibrium\n" } ], "prompt_number": 32 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 6, Page No:2.45" }, { "cell_type": "code", "collapsed": false, "input": "import math;\n\n# Variable Declaration\nh = 6.625*10**-34; # planck's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 5000*10*8-10; # wavelength for optical region in m\nT = 300 # Temperature in Kelvin\nKb = 1.38*10**-23 # Boltzmann constant\n\n# Calculations\n# let R = Rsp/Rst \nR = math.exp((h*c)/(lamda*Kb*T)) - 1; # ratio of spontaneous to stimulated emission\nif R<1:\n print 'Since the spontaneous emission is lesser than stimulated emission \\n hence LASER action is possible at thermal equilibrium'\nelse:\n print 'Since the spontaneous emission is more predominant than stimulated emission\\nhence LASER action is not possible at optical frequencies under thermal equilibrium';\n", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": "Since the spontaneous emission is lesser than stimulated emission \n hence LASER action is possible at thermal equilibrium\n" } ], "prompt_number": 37 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": "Addl_Example 7, Page No:2.46" }, { "cell_type": "code", "collapsed": false, "input": "import math\n\n# Variable Declaration\nh = 6.625*10**-34; # plank's constant\nc = 3*10**8; # vel. of light in m/s\nlamda = 5511.11*10**-10; # wavelength of green LED light in m\nq = 1.6*10**-19; # charge of electron\n\n# Calculations\nEg = (h*c)/lamda; # band gap energy in joules\nE = Eg/q # bang gap energy in eV\n\n# Result\nprint ' Eg = %3.2f' %E,'eV';", "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": " Eg = 2.25 eV\n" } ], "prompt_number": 38 } ], "metadata": {} } ] }