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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 7: Optical Fibre Communication"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.1, Page 206"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt\n",
"\n",
"#Variable declaration\n",
"NA = 0.24;#Numerical Aperture\n",
"delta = 0.014;\n",
"\n",
"#Calculations & Results\n",
"n1 = (NA)/sqrt(2*delta);#Refractive index of first medium \n",
"print 'Refractive index of first medium is ',round(n1,4)\n",
"n2 = n1 - (delta*n1);#Refractive index of secong material\n",
"print 'Refractive index of secong material is ',round(n2,4)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Refractive index of first medium is 1.4343\n",
"Refractive index of secong material is 1.4142\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.2, Page 207"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt,asin,degrees\n",
"\n",
"#Variable declaration\n",
"n1 = 1.49; # Refractive index of first medium\n",
"n2 = 1.44; # Refractive index of second medium\n",
"\n",
"#Calculations & Results\n",
"def deg_to_dms(deg):\n",
" d = int(deg)\n",
" md = abs(deg - d) * 60\n",
" m = int(md)\n",
" sd = (md - m) * 60\n",
" sd=round(sd,2)\n",
" return [d, m, sd]\n",
"\n",
"delta = (n1-n2)/n1; # Index difference\n",
"NA = n1* sqrt(2*delta);\n",
"print 'Numerical Aperture of fiber is',round(NA,3)\n",
"theta = degrees(asin(NA));\n",
"print 'Acceptance angle is ',deg_to_dms(theta),'degrees'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Numerical Aperture of fiber is 0.386\n",
"Acceptance angle is [22, 42, 22.17] degrees\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.3, Page 207"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt,asin,degrees\n",
"\n",
"#Variable declaration\n",
"NA = 0.15 ; # Numerical Aperture of fiber\n",
"n2 = 1.55; # Refractive index of cladding\n",
"n0w = 1.33; # Refractive index of water\n",
"n0a = 1; # Refractive index of air\n",
"\n",
"#Calculations\n",
"def deg_to_dms(deg):\n",
" d = int(deg)\n",
" md = abs(deg - d) * 60\n",
" m = int(md)\n",
" sd = (md - m) * 60\n",
" sd=round(sd,2)\n",
" return [d, m, sd]\n",
"\n",
"n1 = sqrt(NA**2 + n2**2);\n",
"NAW = (sqrt(n1**2 -n2**2))/n0w;\n",
"theta = degrees(asin(NAW));#Acceptance angle in water\n",
"\n",
"#Result\n",
"print 'Acceptance angle in water is ',deg_to_dms(theta),'degrees'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Acceptance angle in water is [6, 28, 32.55] degrees\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.4, Page 216"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import log10\n",
"\n",
"#Variable declaration\n",
"l = 16; # Length of optical fiber in Km\n",
"Pi = 240e-6; # Mean optical length launched in optical fiber in Watts\n",
"Po = 6e-6; # Mean optical power at the output in watts\n",
"\n",
"#Calculations&Results\n",
"alpha = 10*log10(Pi/Po);#Signal attenuation in fiber\n",
"print 'Signal attenuation in fiber',round(alpha),'dB'\n",
"alpha1 = alpha/l;#Signal attenuation per km of the fiber\n",
"print 'Signal attenuation per km of the fiber',round(alpha1),'dB/km'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Signal attenuation in fiber 16.0 dB\n",
"Signal attenuation per km of the fiber 1.0 dB/km\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.5, Page 219"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import pi,exp\n",
"\n",
"#Variable declaration\n",
"Tf = 1400; # Fictive temperature of silicon in Kelvin\n",
"betai = 7e-11; # Isothermal compressibility square meter per newton\n",
"n = 1.46; # Refractive index of silicon\n",
"p = 0.286; # Photoelastic constant of silicon\n",
"lamda = 0.63e-6 # Wavelength in micrometer\n",
"kb = 1.38e-23 # Boltzmann constant in joule per kelvin\n",
"L = 1e3;\n",
"\n",
"#Calculations\n",
"alphas = (8 * pi**3 * n**8 * p**2 * kb * Tf * betai)/(3 * lamda**4);#Rayleigh scattering coefficient\n",
"alphars = exp(-alphas * L);#Loss factor\n",
"\n",
"#Results\n",
"print 'Rayleigh scattering coefficient is ',round(alphas/1e-3,2),'*10^-3 /m'\n",
"print 'Loss factor is',round(alphars,3) #Answer varies due to rounding-off values\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Rayleigh scattering coefficient is 1.2 *10^-3 /m\n",
"Loss factor is 0.302\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.6, Page 222"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration\n",
"alpha = 0.5; # Attenuation of single mode optical fibre in dB per km\n",
"lamda = 1.4; # Operating wavelength of optical fiber in micrometer\n",
"d = 8 # Diameter of fiber in micrometer\n",
"y = 0.6; # Laser source frequency width\n",
"\n",
"#Calculations\n",
"pb = 4.4e-3 * d**2 * lamda**2 * alpha * y;#Threshold optical power in SBS\n",
"prs = 5.9e-2 * d**2 * lamda * alpha;#Threshold optical power in SRS\n",
"\n",
"#Results\n",
"print 'Threshold optical power in SBS',pb/1e-3,'mW'\n",
"print 'Threshold optical power in SRS',prs,'W'\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Threshold optical power in SBS 165.5808 mW\n",
"Threshold optical power in SRS 2.6432 W\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7.7, Page 225"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from math import sqrt, pi\n",
"\n",
"#Variable declaration\n",
"n1 = 1.50; # Refreactive index of forst medium\n",
"delta = 0.003; # Index difference\n",
"lamda = 1.6*1e-6; # Operating wavelength of fober in meter\n",
"\n",
"#Calculations&Results\n",
"n2 = sqrt(n1**2-(2*delta*n1**2));#refractive index of cladding\n",
"#Substituting n2^2 = n1^2 - 2*delta*n1^2 in euation of Rc,\n",
"rc = (3*n1**2*lamda)/(4*pi*((2*delta*n1**2)**(3./2)));#The critical radius of curvature for which bending losses occur \n",
"print 'The critical radius of curvature for which bending losses occur is ',round(rc/1e-6,2),'um'\n",
"#Incorrect answer in the textbook\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The critical radius of curvature for which bending losses occur is 547.92 um\n"
]
}
],
"prompt_number": 7
}
],
"metadata": {}
}
]
}
|
