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diff --git a/Optical_Communication_by_Anasuya_Kalavar/chapter4.ipynb b/Optical_Communication_by_Anasuya_Kalavar/chapter4.ipynb new file mode 100755 index 00000000..408746a4 --- /dev/null +++ b/Optical_Communication_by_Anasuya_Kalavar/chapter4.ipynb @@ -0,0 +1,413 @@ +{ + "metadata": { + "name": "", + "signature": "sha256:c80be9ee73d5adb979ad6bf2343ea3cff1243505e35fc82560bd445f960931b7" + }, + "nbformat": 3, + "nbformat_minor": 0, + "worksheets": [ + { + "cells": [ + { + "cell_type": "heading", + "level": 1, + "metadata": {}, + "source": [ + "Chapter4 - Signal Degradation in fibers" + ] + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.3.1, page 4-4" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "from __future__ import division\n", + "from numpy import sqrt, pi, log10\n", + "L=10 #fiber length in km\n", + "Pin=150*10**-6 #input power\n", + "Pout=5*10**-6 #output power\n", + "ln=20 #length of optical link\n", + "interval=1 #splices after interval of 1 km\n", + "l=1.2 #loss due to 1 splice\n", + "attenuation=10*log10(Pin/Pout) \n", + "alpha=attenuation/L \n", + "attenuation_loss=alpha*20 \n", + "splices_loss=(ln-interval)*l \n", + "total_loss=attenuation_loss+splices_loss \n", + "power_ratio=10**(total_loss/10) \n", + "print \"Signal attenuation is %.2f dBs.\\nSignal attenuation is %.3f dB/Km.\\nTotal loss in 20 Km fiber is %.2f dbs.\\nTotal attenuation is %.2f dBs.\\ninput/output ratio is %0.e.\" %(attenuation,alpha,attenuation_loss,total_loss,power_ratio) \n", + "# Answer wrong for last part." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Signal attenuation is 14.77 dBs.\n", + "Signal attenuation is 1.477 dB/Km.\n", + "Total loss in 20 Km fiber is 29.54 dbs.\n", + "Total attenuation is 52.34 dBs.\n", + "input/output ratio is 2e+05.\n" + ] + } + ], + "prompt_number": 32 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.6.1, page 4-12" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "from numpy import exp\n", + "beta_c=8*10**-11 #isothermal compressibility\n", + "n=1.46 #refractive index\n", + "P=0.286 #photoelastic constat\n", + "k=1.38*10**-23 #Boltzmnn constant\n", + "T=1500 #temperature\n", + "L=1000 #length\n", + "lamda=1000*10**-9 #wavelength\n", + "gamma_r = 8*(3.14**3)*(P**2)*(n**8)*beta_c*k*T/(3*(lamda**4)) #computing coefficient\n", + "attenuation=exp(-gamma_r*L) #computing attenuation\n", + "print \"Attenuation due to Rayleigh scattering is %.3f.\" %(attenuation) " + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Attenuation due to Rayleigh scattering is 0.794.\n" + ] + } + ], + "prompt_number": 10 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.6.2, page 4-12" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "beta_c=7*10**-11 #isothermal compressibility\n", + "n=1.46 #refractive index\n", + "P=0.29 #photoelastic constat\n", + "k=1.38*10**-23 #Boltzmnn constant\n", + "T=1400 #temperature\n", + "L=1000 #length\n", + "lamda=0.7*10**-6 #wavelength\n", + "gamma_r = 8*(3.14**3)*(P**2)*(n**8)*beta_c*k*T/(3*(lamda**4)) #computing coefficient\n", + "attenuation=exp(-gamma_r*L) #computing attenuation\n", + "gamma_r=gamma_r\n", + "print \"Raleigh Scattering corfficient is %.3e per meter\" %(gamma_r) \n", + "#Attenuation is not calcualted in textbook\"\n", + "print \"Attenuation due to Rayleigh scattering is %.3f\" %(attenuation) \n", + "#answer for Raleigh Scattering corfficient in the book is given as 0.804d-3, deviation of 0.003d-3" + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Raleigh Scattering corfficient is 8.074e-04 per meter\n", + "Attenuation due to Rayleigh scattering is 0.446\n" + ] + } + ], + "prompt_number": 17 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.7.1, page 4-17" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "d=5 #core diameter\n", + "alpha=0.4 #attenuation\n", + "B=0.5 #Bandwidth\n", + "lamda=1.4 #wavelength\n", + "PB=4.4*10**-3*d**2*lamda**2*alpha*B #computing threshold power for SBS\n", + "PR=5.9*10**-2*d**2*lamda*alpha #computing threshold power for SRS\n", + "PB=PB*10**3 \n", + "PR=PR*10**3 \n", + "print \"Threshold power for SBS is %.1f mW.\\nThreshold power for SRS is %.3f mW.\" %(PB,PR) \n", + "#NOTE - Calculation error in the book while calculating threshold for SBS.\n", + "#Also, while calculating SRS, formula is taken incorrectly, \n", + "#Bandwidth is multiplied in second step, which is not in the formula.\") " + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Threshold power for SBS is 43.1 mW.\n", + "Threshold power for SRS is 826.000 mW.\n" + ] + } + ], + "prompt_number": 19 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.8.1, page 4-18" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "n1=1.5 #refractive index of core\n", + "delta=0.03/100 #relative refractive index\n", + "lamda=0.82*10**-6 #wavelength\n", + "n2=sqrt(n1**2-2*delta*n1**2) #computing cladding refractive index\n", + "Rc=(3*n1**2*lamda)/(4*3.14*(n1**2-n2**2)**1.5) #computing critical radius\n", + "Rc=Rc*10**3 \n", + "print \"Critical radius is %.f micrometer.\" %(Rc) " + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Critical radius is 9 micrometer.\n" + ] + } + ], + "prompt_number": 22 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.8.2, page 4-20" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "n1=1.45 #refractive index of core\n", + "delta=3.0/100 #relative refractive index\n", + "lamda=1.5*10**-6 #wavelength\n", + "a=5*10**-6 #core radius\n", + "n2=sqrt(n1**2-2*delta*n1**2) #computing cladding refractive index\n", + "Rc=(3*n1**2*lamda)/(4*3.14*(n1**2-n2**2)**0.5) #computing critical radius for single mode\n", + "Rc=Rc*10**6 \n", + "print \"Critical radius is %.2f micrometer\" %(Rc) \n", + "lamda_cut_off= 2*3.14*a*n1*sqrt(2*delta)/2.405 \n", + "RcSM= (20*lamda/(n1-n2)**1.5)*(2.748-0.996*lamda/lamda_cut_off)**-3 #computing critical radius for single mode\n", + "RcSM=RcSM*10**6 \n", + "print \"Critical radius for single mode fiber is %.2f micrometer.\" %(RcSM) \n", + "#Calculation error in the book.(2.748-0.996*lamda/lamda_cut_off)**-3 in this term raised to -3 is not taken in the book." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Critical radius is 2.12 micrometer\n", + "Critical radius for single mode fiber is 226.37 micrometer.\n" + ] + } + ], + "prompt_number": 24 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.13.1, page 4-28" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "lamda=1550*10**-9 \n", + "lamda0=1.3*10**-6 \n", + "s0=0.095 \n", + "Dt=lamda*s0/4*(1-(lamda0/lamda)**4) #computing material dispersion\n", + "Dt=Dt*10**9 \n", + "print \"Material dispersion at 1550 nm is %.1f ps/nm/km\" %Dt\n", + "#answer in the book is wrong." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Material dispersion at 1550 nm is 18.6 ps/nm/km\n" + ] + } + ], + "prompt_number": 26 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.14.1, page 4-33" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "tau=0.1*10**-6 #pulse broadning\n", + "dist=20*10**3 #distance\n", + "Bopt=1/(2*tau) #computing optical bandwidth\n", + "Bopt=Bopt*10**-6 \n", + "dispertion=tau/dist #computing dispersion\n", + "dispertion=dispertion*10**12 \n", + "BLP=Bopt*dist #computing Bandwidth length product\n", + "BLP=BLP*10**-3 \n", + "print \"optical bandwidth is %d MHz.\\nDispersion per unit length is %d ns/km.\\nBandwidth length product is %d MHz.km.\" %(Bopt,dispertion,BLP) " + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "optical bandwidth is 5 MHz.\n", + "Dispersion per unit length is 5 ns/km.\n", + "Bandwidth length product is 100 MHz.km.\n" + ] + } + ], + "prompt_number": 27 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.15.1, page 4-34" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "RSW=0.0012 #relative spectral width\n", + "lamda=0.90*10**-6 #wavelength\n", + "L=1 #distance in km (assumed)\n", + "P=0.025 #material dispersion parameter\n", + "c=3*10**5 #speed of light in km/s\n", + "M=10**3*P/(c*lamda) #computing material dispersion\n", + "sigma_lamda=RSW*lamda \n", + "sigmaM=sigma_lamda*L*M*10**7 #computing RMS pulse broadning\n", + "sigmaB=25*L*M*10**-3 \n", + "print \"Material dispersion parameter is %.2f ps/nm/km.\\nRMS pulsr broadning when sigma_lamda is 25 is %.1f ns/km.\\nRMS pulse broadning is %.2f ns/km.\" %(M,sigmaB,sigmaM) \n", + "#answer in the book for RMS pulse broadning is wrong." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Material dispersion parameter is 92.59 ps/nm/km.\n", + "RMS pulsr broadning when sigma_lamda is 25 is 2.3 ns/km.\n", + "RMS pulse broadning is 1.00 ns/km.\n" + ] + } + ], + "prompt_number": 29 + }, + { + "cell_type": "heading", + "level": 2, + "metadata": {}, + "source": [ + "Example 4.17.1, page 4-37" + ] + }, + { + "cell_type": "code", + "collapsed": false, + "input": [ + "L=10 #length of optical link\n", + "n1=1.49 #refractive index\n", + "c=3*10**8 #speed of light\n", + "delta=1.0/100 #relative refractive index\n", + "delTS=L*n1*delta/c #computing delay difference\n", + "delTS=delTS*10**12 \n", + "sigmaS=L*n1*delta/(2*sqrt(3)*c) #computing rms pulse broadning\n", + "sigmaS=sigmaS*10**12 \n", + "B=1/(2*delTS) #computing maximum bit rate\n", + "B=B*10**3 \n", + "B_acc=0.2/(sigmaS) #computing accurate bit rate\n", + "B_acc=B_acc*10**3 \n", + "BLP=B_acc*L #computing Bandwidth length product\n", + "print \"Delay difference is %d ns.\\nRMS pulse broadning is %.1f ns.\\nBit rate is %.1f Mbit/s.\\nAccurate bit rate is %.3f Mbits/s.\\nBandwidth length product is %.1f MHz.km\" %(delTS,sigmaS,B,B_acc,BLP) \n", + "#answer for maximum bit rate is given as 1.008 Mb/s, deviation of 0.008 Mb/s." + ], + "language": "python", + "metadata": {}, + "outputs": [ + { + "output_type": "stream", + "stream": "stdout", + "text": [ + "Delay difference is 496 ns.\n", + "RMS pulse broadning is 143.4 ns.\n", + "Bit rate is 1.0 Mbit/s.\n", + "Accurate bit rate is 1.395 Mbits/s.\n", + "Bandwidth length product is 13.9 MHz.km\n" + ] + } + ], + "prompt_number": 31 + } + ], + "metadata": {} + } + ] +}
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