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{
"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": {}
}
]
}
|
