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{
"metadata": {
"name": "",
"signature": "sha256:46a82c7fe1b65af7ee26b9fa38521b26c61cee31bc75dd5001fe45442416739c"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"13: Optical Fibre"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.1, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"n1=1.49; #refractive index of core\n",
"n2=1.46; #refractive index of cladding\n",
"\n",
"#Calculation \n",
"NA=math.sqrt((n1**2)-(n2**2)); #Numerical aperture\n",
"\n",
"#Result\n",
"print \"The numerical aperture is\",round(NA,1)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The numerical aperture is 0.3\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.2, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"NA=0.5; #numerical aperture of fibre \n",
"n0=1; #refractive index of the medium(air)\n",
"\n",
"#Calculation \n",
"i=math.asin(NA/n0); #acceptance angle(radian)\n",
"i=i*180/math.pi; #angle(degrees)\n",
"\n",
"#Result\n",
"print \"The acceptance angle is\",i,\"degrees\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The acceptance angle is 30.0 degrees\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.3, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"NA=0.25; #numerical apperture\n",
"lamda=0.75; #wavelength(micro m)\n",
"a=25; #core radius(micro m)\n",
"\n",
"#Calculation \n",
"f=(2*math.pi*a*NA)/lamda; #normalised frequency\n",
"Ng=(f**2)/2; #number of guided modes\n",
"\n",
"#Result\n",
"print \"The number of guided modes is\",int(Ng)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The number of guided modes is 1370\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.4, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"pi=100; #mean optical power launched(micro m)\n",
"po=5; #mean optical power at fibre output(micro W)\n",
"l=6; #length(km)\n",
"\n",
"#Calculation \n",
"S=10*math.log10(pi/po); #signal attenuation(dB)\n",
"Sk=S/l; #signal attenuation(dB/km)\n",
"\n",
"#Result\n",
"print \"The signal attenuation is\",round(Sk,3),\"dB/km\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The signal attenuation is 2.168 dB/km\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.5, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"ns=2.89; #sum of refractive indices of core & cladding\n",
"nd=0.03; #difference of refractive indices of core & cladding\n",
"\n",
"#Calculation \n",
"NA=math.sqrt(ns*nd); #numerical apperture\n",
"\n",
"#Result\n",
"print \"The numerical apperture for the optical fibre is\",round(NA,2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The numerical apperture for the optical fibre is 0.29\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.6, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"NA=0.28; #numerical aperture\n",
"a=30; #core radius(micro m)\n",
"lamda=0.8; #wavelength(micro m)\n",
"\n",
"#Calculation \n",
"f=(2*math.pi*a*NA)/lamda; #normalised frequency\n",
"Ng=f**2/2; #number of guided modes\n",
"\n",
"#Result\n",
"print \"The number of guided modes is\",int(Ng)\n",
"print \"answer in the book varies due to rounding off errors\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The number of guided modes is 2176\n",
"answer in the book varies due to rounding off errors\n"
]
}
],
"prompt_number": 14
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.7, Page number 250"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"S=2; #signal attenuation(dB/km)\n",
"l=1; #length(km)\n",
"p0=20; #mean optical power at fibre output(micro W)\n",
"\n",
"#Calculation \n",
"pi=p0*10**(S/10); #mean optical power launched into fibre(micro W)\n",
"\n",
"#Result\n",
"print \"The mean optical power launched into a fibre is\",round(pi,1),\"micro W\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The mean optical power launched into a fibre is 31.7 micro W\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.8, Page number 251"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"S=2.3; #Signal attenuation(dB/km)\n",
"l=4; #length(km)\n",
"\n",
"#Calculation \n",
"S=S*l; #signal attenuation for 4km in dB\n",
"P=10**(S/10); #ratio of mean optical power\n",
"\n",
"#Result\n",
"print \"ratio of mean optical power is\",round(P,1)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"ratio of mean optical power is 8.3\n"
]
}
],
"prompt_number": 18
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 13.9, Page number 251"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"op=1/4; #ratio\n",
"\n",
"#Calculation \n",
"#S=10*log(pi/po)\n",
"S=10*math.log10(1/op); #signal attenuation(dB)\n",
"\n",
"#Result\n",
"print \"Signal attenuation is\",int(S),\"dB\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Signal attenuation is 6 dB\n"
]
}
],
"prompt_number": 20
}
],
"metadata": {}
}
]
}
|
