{ "metadata": { "name": "", "signature": "sha256:7bd6880823e892a54fce1336eeffd037b53706d16df72c924dbe7c27da815476" }, "nbformat": 3, "nbformat_minor": 0, "worksheets": [ { "cells": [ { "cell_type": "heading", "level": 1, "metadata": {}, "source": [ "Chapter6:FIBER OPTICS AND HOLOGRAPHY" ] }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex6.1:pg-189" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#to calculate critical angle for core-cladding interface\n", "n1=1.5\n", "n2=1.45\n", "thetac=math.degrees(math.asin(n2/n1))\n", "theta1=90-thetac\n", "\n", "print \"critical angle for core-cladding interface is theta1=\",round(theta1),\"degree\"\n", "#to calculate acceptance angle in air for fibre and corresponding angle of obliquences\n", "na=1\n", "thetaa=math.degrees(math.asin(n1*0.26/na))\n", "\n", "print \"acceptance angle thetaa=\",round(thetaa),\"degree\"\n", "#to calculate numerical aperture\n", "NA=((n1+n2)*(n1-n2))**(1/2.0)\n", "print \"numerical aperture of fibre is NA=\",round(NA,4),\"unitless\"\n", "#to calculate % of light\n", "per=(NA)**2*100\n", "print \"light collected is per=\",round(per,2),\"%\"\n", "\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "critical angle for core-cladding interface is theta1= 15.0 degree\n", "acceptance angle thetaa= 23.0 degree\n", "numerical aperture of fibre is NA= 0.3841 unitless\n", "light collected is per= 14.75 %\n" ] } ], "prompt_number": 8 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex6.2:pg-190" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#to calculate numerical aperture\n", "Del=0.02 #relative refractive index difference between the core and the cladding of the fibre i.e. del=(n1-n2)/n1\n", "n1=1.46 #refractive index of core of W-step index fibre \n", "n2=n1-Del*n1\n", "NA=((n1+n2)*(n1-n2))**(1/2.0)\n", "print \"numerical aperture is NA=\",round(NA,2),\"unitless\"\n", "#to calculate critical angle at the core cladding interface within the fibre\n", "thetac=math.degrees(math.asin(n2/n1))\n", "print \"thetac=\",int(thetac),\"degree\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "numerical aperture is NA= 0.29 unitless\n", "thetac= 78 degree\n" ] } ], "prompt_number": 10 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex6.3:pg-190" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#to calculate refractive index of the cladding\n", "a=35.0*10**-6 #core diameter in micrometre\n", "#formula is del=(n1-n2)/n1\n", "#we get\n", "Del=1.5/100 \n", "n1=1.46 #refractive index of the fibre \n", "lamda=0.85*10**-6 #wavelength in micrometer\n", "n2=n1-Del*n1\n", "print \"refractive index is n2=\",round(n2,3),\"unitless\"\n", "#to calculate normalised frequency V number of the fibre\n", "V=round((2*math.pi*a*n1*0.173)/lamda,1)\n", "print \"normalised frequency V number of the fibre is V=\",V,\"unitless\"\n", "#to calculate total number of guided modes in the fibre\n", "M=(V**2)/2.0\n", "print \"total number of guided modes in the fibre is M=\",int(M),\"modes\"\n", "\n", "\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "refractive index is n2= 1.438 unitless\n", "normalised frequency V number of the fibre is V= 65.3 unitless\n", "total number of guided modes in the fibre is M= 2132 modes\n" ] } ], "prompt_number": 15 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex6.4:pg-191" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#to calculate cut-off wavelength of the fibre\n", "#(2*del)**(1/2)=(2*(n1-n2)/n1)**(1/2)=(0.005)**(1/2)=0.071\n", "a=5*10**-6 #radius in micrometre\n", "n1=1.46 #core refractive index in micrometre\n", "Vc=2.405 #cut-off value of V parametre for single mode operation\n", "#formula is LAMBDAc=(2*math.pi*a*n1*(2*del)**(1/2))/Vc \n", "lamdac=(2*math.pi*a*n1*0.071)/Vc\n", "print \"cut-off wavelength is LAMBDAc=\",round(lamdac/1e-6,2),\"micrometre\"\n", "\n", "# answer is slightly different due to approximation in book\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "cut-off wavelength is LAMBDAc= 1.35 micrometre\n" ] } ], "prompt_number": 5 }, { "cell_type": "heading", "level": 2, "metadata": {}, "source": [ "Ex6.5:pg-191" ] }, { "cell_type": "code", "collapsed": false, "input": [ "import math\n", "#to calculate maximum and minimum value of phase constant\n", "lamda=0.8*10**-6 #wavelength in micrometre\n", "n1=1.6*10**-6 \n", " #refractive indices in micrometre\n", "n2=1.44*10**-6\n", "maximum=(2*math.pi*n1)/lamda\n", "minimum=(2*math.pi*n2)/lamda\n", "print \"maximum value of phase constant is maximum=\",round(maximum,3),\"radian/micrometre\"\n", "print \"minimum value of phase constant is minimum=\",round(minimum,2),\"radian/micrometre\"\n" ], "language": "python", "metadata": {}, "outputs": [ { "output_type": "stream", "stream": "stdout", "text": [ "maximum value of phase constant is maximum= 12.566 radian/micrometre\n", "minimum value of phase constant is minimum= 11.31 radian/micrometre\n" ] } ], "prompt_number": 6 } ], "metadata": {} } ] }