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UNIVERSITI TUN HUSSEIN ONN MALAYSIA
FACULTY OF SCIENCE, TECHNOLOGY, AND HUMAN
DEVELOPMENT
PROPOSAL TITLE :
REFRACTIVE INDEX FIBER SENSOR IN DIFFERENT
SOLUTION
LASER TECHNOLOGY
BWC 31403
NAME
MATRIC NUMBER
ATIQAH NABIEHA BT AZMI
AW120091
FATIN SHAQIRA BT ABDUL HADI AW120064
NURUL ATIQAH BT AHMAD
LECTURER :
DR ZAHARIAH BT ZAKARIA
DR NOORAZURA BT AWANG
AW120152
PROJECTTITLE :
REFRACTIVE INDEX FIBER SENSOR
IN DIFFERENT SOLUTION
1.0
INTRODUCTION
1.1
Background
The project is about the determination of total internal reflection in different solution.
Each solution is different in value of refractive index. The solutions used in this experiment
are distilled water, salt solution, sugar solution and cooking oil. Normally, we do not know
that the value ofrefractive index affect the value of total internal reflection. The reasons we
choose these projects was to compare the value of total internal reflection in different
refractive index of solution.
1.2
Statement of Problem
This project was done to find the solutions to the following problem:
i)
Cannot measure accurately the value of the total internal reflection.
ii)
Different solutions have different value of refractive index thus give effect on
value of total internal reflection.
1.3
Objectives
i)
To identify the value of total internal reflection using Optical Spectrum Analyzer in
different solution.
ii)
To determine the output power of laser based on differentvalue of refractive index of
solution.
1.4
Significant Of Study
This experiment was done to expose the relationship between total internal reflection
and refractive index of different solution to students. These allowed the students especially
Secondary School Students to determine the value of total internal reflection precise and
accurately.
1.5
Limitation of Study
We were done conducting the experiment and the result was obtained even there were
some limitations. First of all, the time required to complete these project was too short which
about three weeks. Besides, the lack of knowledge on using Optical Spectrum Analyzer also
give effect to start the experiment. It consume a longer period of time compared to the
original plan. Lastly, the man power of these project was three students.
1.6
Definition of Terms
Total internal reflection :A phenomenon occur when light passing through a medium at a
certain angle and bounce at larger angle.
Refractive index :The bending of a ray of lightwhen it enters a differentmedium where pass
through from one medium into another.
Fiber Optic Circulator : A non-reciprocal device that direct an optical signal (light) from one
port to the next port, in only one direction at a time.
Laser pointer : A small device with a power sourcethat emit very narrow coherent lowpowered laser beam of visible light through a process of optical amplification based on the
simulated emission of electromagnetic radiation.
Power meter :A device for the measurement of the power in a laser beam.
1.7
Methodology
i)
Experimental work
For fulfill our objectives, we are conducting the experiment as Figure1 below. The
different solution will be used in this experiment. They are distilled water, salt
solution, sugar solution and cooking oil. The result or value of total internal
reflection was obtained using power meter.
Figure 1
Figure 2
2.0
LITERATURE REVIEW
2.1
Theory
2.1.1 Total Internal Reflection :
When light goes from a denser medium to a less dense medium, as the angle of incidence
exceeds the critical angle, the ray reflects back to the denser medium. This phenomenon is
called Total Internal Reflection. The total Internal Reflection is a very efficient reflection, as
the loss of light energy is almost negligible.The following Figure 1 explains when the angle
incidence is greater than the critical angle, all the light undergoes reflection.
Figure 1
2.1.2 Polarization Independent Circulator
Figure 3
Figure 3 shows the configuration of the experiment. We are conducting experiment using the
circulator. Circulators are non-reciprocating, one-directional, and have three-port device
designed which is port 1, port 2 and port 3. Every port has its own colour to show the type of
each port. For example port 1 in red colour, port 2 in blue colour and port 3 in white colour.
Each circulator functions to add a signal in one direction while removing the signal in the
other. A circulator will be passing light from one port to another port. The movement occurs
in the same direction the light is traveling, from the first port to the second port, and the
second port to the third port. In this experiment, the port 1 connect with the laser pointer will
be move to the port 2 and touch the different solution in the beaker. Then, after touch the
different solution using port 2 it will transfer to the port 3 that connect to the power meter.
When power meter detect a laser beam from port 2 its will be show the value of power pass
through it. Each circulator functions to add a signal in one direction while removing the
signal in the other.
2.1.3 Refractive Index
In optics the refractive index or index of refraction n of an optical medium is
a dimensionless number that describes how light, or any other radiation, propagates through
that medium. It is defined as
……………….(1)
where c is the speed of light in vacuum and v is the phase velocity of light in the medium.
In this experiment, the refractive index of the solutions are determined from the relation
between the power intensity of the light, peak wavelength, and speed of light in the different
medium.
E = hυ
where ,
E is the energy of light in vacuum,
h is the Planck’s constant,
…………...…..(2)
υ is the frequency of light.
c=υλ
𝒄
υ=𝝀
……………….(3)
……………….(4)
By substituting Equation (4) into Equation (2), we simply get :
𝒉𝒄
E=
𝝀
𝑬𝝀
c=
𝒉
……………….(5)
……………….(6)
To obtain the refractive index of the solution, we substitute Equation (6) into Equation (1).
𝑬𝝀
n = 𝒉𝒗
……………….(7)
The energy of the light passing through the medium can be obtain from :
𝑷
I=𝑨
A=
𝑷
𝑰
……………….(8)
……………….(9)
where
P is the power loss in between two the media (vacuum and the solution), and
A is the area.
Power loss, P is also defined as the product of number of photon in medium, N and energy
that pass through it, E.
P = NE
…………….(10)
So, we get the equation for power intensity by substituting Equation (9) into Equation (8).
I=
𝑵𝑬
E=
𝑨
𝑰𝑨
𝑵
where
……………...(11)
……………...(12)
I is the Power Intensity in Watts, and
N is the number of photon.
So, by combining Equation (7) and (12), we get :
𝐼𝐴𝜆
…………….(13)
n = 𝑁ℎ𝑣
2.2
Apparatus :
1) Circulator
2) Laser Pointer
3) Power meter
4) Solution :
i)
distilled water
ii)
salt solution
iii)
sugar solution
iv)
cooking oil
2.3
Procedure :
Figure 4
The experiment is set up as in the Figure 4 above. The different solution is used to determine
the output power in them. They are distilled water, salt solution, sugar solution and cooking
oil. The result or value of total internal reflection was obtained using power meter in terms of
power (dBm).
3.0
RESULTS AND DISCUSSION
3.1
Result
Table 1 below shows the graph of power of reflection versus wavelength in nanometer (nm).
The peak wavelength in the graph describes the value of total internal reflection from the
source which is laser pointer. The reference power intensity, I0 is fixed about 59.51 dBm.
From the graph, we can determine the value of power loss using the formula :
Power loss = Reference Power Intensity – Power Intensity
Graph
Power
Power
Peak
Speed of
Intensity,
loss, P
wavelength
light in
I
(Watts)
(nm)
solution
(x 10 8 ms-1)
(Watts)
61.39
831.92
1548.80
2.25
37.15
856.16
1548.80
2.19
29.65
863.66
1548.80
2.17
0.07
893.24
1547.60
2.04
Table 1
Guideline for colour of graph :
Reference value
Distilled water
Salt solution
Sugar solution
Oil
From Table 1 above, we can conclude that increase the value power density (Watts), decrease
the value of loss (Watts)in the different solution that used.
3.2
Data Analysis
From the data obtained, we can find the value of refractive index for each of the solution. By
using Equation (13), the solution is shown below :
𝐼𝐴𝜆
n = 𝑁ℎ𝑣 ……. Equation (13)
Types of solution
Area, A (m2)
Number of Photon, N
Distilled Water
13.55
6.49 × 1021
Sugar Solution
23.05
6.69 × 1021
Salt Solution
29.13
6.75 × 1021
Cooking Oil
12760.57
6.98 × 1021
Table 2
Types of
Theoretical
Experimental Refractive index,
solution
Refractive
n
Percentage Differrence %
Index
𝐼𝐴𝜆
n = 𝑁ℎ𝑣
Distilled
1.33
Water
% Diff
Experimental Value−Theoretical Value
=
=
(61.39)(13.55)(1548.80 × 10−9 )
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
× 100%
=0%
(6.49 ×1021 )(6.63 × 10−34 )(2.25 × 108 )
= 1.33
𝐼𝐴𝜆
n = 𝑁ℎ𝑣
Sugar
1.36
Solution
% Diff
Experimental Value−Theoretical Value
=
=
(37.15)(23.05)(1548.80 × 10−9 )
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
× 100%
= 0.74 %
(6.69 ×1021 )(6.63 × 10−34 )(2.19 × 108 )
= 1.37
𝐼𝐴𝜆
n = 𝑁ℎ𝑣
Salt Solution
1.38
=
(29.65)(29.13)(1548.80 × 10−9 )
(6.75 ×1021 )(6.63 × 10−34 )(2.17 × 108 )
= 1.38
% Diff
Experimental Value−Theoretical Value
=
=0%
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
× 100%
n=
Cooking Oil
1.47
𝐼𝐴𝜆
% Diff
𝑁ℎ𝑣
Experimental Value−Theoretical Value
=
=
(0.07)(12760.57)(1547.60 × 10−9 )
=0%
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒
× 100%
(6.98 ×1021 )(6.63 × 10−34 )(2.04 × 108 )
= 1.47
Table 3
Based on the analysis done, the value of refractive index increase with the decrease in power
intensity. This relationship also can be described using the line graph below, Figure 4.
Figure 4
4.0
CONCLUSION
Based on the data obtained, the value of refractive index for each solution is determined. The
value of refractive index obtained for distilled water is 1.33, sugar solution is 1.37, salt
solution is 1.38 and for cooking oil is 1.47.
The percentage difference between the theoretical value and the experimental value of the
refractive index is 0 % for three types of solution, distilled water, salt solution and cooking
oil. For sugar solution, the percentage difference is 0.74 %.