{
"metadata": {
"name": "",
"signature": "sha256:69c313bd7e7f4ca84b1b5e5f091a7854a8c80d86bc1470f5cbc9e6d39211d1ba"
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"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"chapter5 - Optical fiber connection : splicing"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.2.1, page 5-2"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"from numpy import sqrt, pi, log10\n",
"n1=1.47 #refractive index of fiber\n",
"n=1 #refractive index of air\n",
"r=((n1-n)/(n1+n))**2 #computing fraction of light reflected\n",
"loss=-10*log10(1-r) #loss\n",
"total_loss=2*loss \n",
"print \"r = %.3f, which means %.1f percent of the transimitted light is reflected at one interface\" %(r,r*100) \n",
"print \"Total loss is %.3f dB\" %(total_loss) \n",
"#answer in the book for total loss of fiber is wrong."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"r = 0.036, which means 3.6 percent of the transimitted light is reflected at one interface\n",
"Total loss is 0.320 dB\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.2.2, page 5-4"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from numpy import arccos\n",
"n1=1.47 #refractive index of fiber\n",
"n=1 #refractive index of air\n",
"d=40*10**-6 #core diameter\n",
"y=4*10**-6 #lateral dispalcement\n",
"a=d/2 #computing core radius\n",
"eta_lateral = (16*(n1/n)**2)/(pi*(1+(n1/n))**4)*(2*arccos(y/(2*a))-(y/a)*(1-(y/(2*a))**2)**0.5) #computing eta_lateral with air gap\n",
"loss=-10*log10(eta_lateral) #computing loss when air gap is present\n",
"eta_lateral1=(2*arccos(y/(2*a))-(y/a)*(1-(y/(2*a))**2)**0.5)/pi #computing eta_lateral without air gap\n",
"loss1=-10*log10(eta_lateral1) #computing loss when air gap is not present\n",
"print \"loss with air gap is %.2f dB.\\nloss with no air gap is %.2f dB.\" %(loss,loss1) \n",
"#answer in the book for loss with air gap is wrong"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"loss with air gap is 0.91 dB.\n",
"loss with no air gap is 0.59 dB.\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.2.3, page 5-5"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"n1=1.48 #refractive index of fiber\n",
"n=1 #refractive index of air\n",
"theta=10 #angle in degree\n",
"NA1=0.3 \n",
"NA2=0.6\n",
"eta_angular1= (16*(n1/n)**2)/((1+(n1/n))**4)*(1-((n*theta*pi/180)/(pi*NA1))) #computing eta angular\n",
"eta_angular2= (16*(n1/n)**2)/((1+(n1/n))**4)*(1-((n*theta*pi/180)/(pi*NA2))) #computing eta angular\n",
"loss1=-10*log10(eta_angular1) #computing loss\n",
"loss2=-10*log10(eta_angular2) #computing loss\n",
"print \"\\nLoss when NA is %.1f is %.2f dB.\\nLoss when NA is %.1f is %.2f dB.\" %(NA1,loss1,NA2,loss2) "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"\n",
"Loss when NA is 0.3 is 1.22 dB.\n",
"Loss when NA is 0.6 is 0.75 dB.\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.4.1, page 5-15"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from numpy import exp\n",
"d=1*10**-6 #lateral displacement\n",
"W=4.95*10**-6 #MFD\n",
"Lsm_lat= -10*log10(exp(-(d/W)**2)) #computing loss\n",
"print \"Insertion loss is %.2f dB.\" %(Lsm_lat) "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Insertion loss is 0.18 dB.\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.4.2, page 5-15 "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"lamda=1.3*10**-6 #wavelength\n",
"theta=1 #angle in degree\n",
"n2=1.465 #cladding refractive index\n",
"W=4.95*10**-6 #MFD\n",
"Lsm_ang= -10*log10(exp(-(pi*n2*W*(theta*pi/180)/lamda)**2)) #computing loss\n",
"print \"Insertion loss is %.2f dB.\" %(Lsm_ang) "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Insertion loss is 0.41 dB.\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.6.1, page 5-28 "
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"p1=50*10**-6 \n",
"p2=0.003*10**-6 \n",
"p3=25*10**-6 \n",
"p4=26.5*10**-6\n",
"EL=10*log10(p1/(p3+p4)) #computing excess loss\n",
"IL13=10*log10(p1/p3) #computing insertion loss\n",
"IL14=10*log10(p1/p4) #computing insertion loss\n",
"ct=10*log10(p2/p1) #computing cross talk\n",
"sr=(p3/(p3+p4))*100 #computing split ratio\n",
"print \"\"\"Excess loss is %.2f dB.\n",
"Insertion loss from port 1 to port 3 is %.2f dB.\n",
"Insertion loss from port 1 to port 4 is %.2f dB.\n",
"cross talk is %.2f dB.\\nSplit ratio is %.2f percent\"\"\" %(EL,IL13,IL14,ct,sr ) \n",
"#Printing and calculation error in the book.Minus sign is not printed in the answer of excess loss.\n",
"#P1 is taken 25 instead of 50 while calculating cross talk. "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Excess loss is -0.13 dB.\n",
"Insertion loss from port 1 to port 3 is 3.01 dB.\n",
"Insertion loss from port 1 to port 4 is 2.76 dB.\n",
"cross talk is -42.22 dB.\n",
"Split ratio is 48.54 percent\n"
]
}
],
"prompt_number": 14
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5.6.2, page 5-29"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"N=16 #Number of ports\n",
"Pin=1*10**-3 #input power\n",
"Pout=12*10**-6 #output power\n",
"split_loss=10*log10(N) #computing split loss\n",
"excess_loss=10*log10(Pin/(Pout*N)) #computing excess loss\n",
"total_loss=split_loss+excess_loss #computing total loss\n",
"insertion_loss= 10*log10(Pin/Pout) #computing insertion loss\n",
"print \"Total loss is %.2f dB.\\nInsertion loss is %.2f dB.\" %(total_loss,insertion_loss) \n",
"#answer in the book for Total loss & insertion loss are wrong."
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Total loss is 19.21 dB.\n",
"Insertion loss is 19.21 dB.\n"
]
}
],
"prompt_number": 15
}
],
"metadata": {}
}
]
}