WINTER 2016
PURPOSE:
APPARATUS:
Fiber optics of various lengths
Trainer boards
Function generator and LED Circuits
Radio
Wood board and tape
Reflective Material
Paper
Ac voltmeter
Cables
INTRODUCTION:
Fiber optics refers to a field of study under both engineering and applied sciences. It deals with the designing and usage of optical fibers. The fibers are flexible and transparent manufactured through the drawing of plastic or silica (glass) to diameters slightly greater than those of human hairs. Most often, optical fibers serve in the transmission of light between the two fiber’s ends. They find a wide use communications since they can transmit higher bandwidth (data rate) information over extended distances. They allow the transmission of information as pulses of light through plastic and glasses. Plastic and glass fibers are preferable to metallic ones since they exhibit the advantage of fewer signal losses. Secondly, there is minimal electromagnetic interference in plastic and glass fibers, unlike metallic fibers. Thirdly, the optical fibers are applicable in illumination. One can wrap them in bundles to carry images since they can permit confined space viewing like in the fiberscope scenario. A fiber-optic communication process involves the creation of an optical signal using a transmitter. The operator then relays the created signal via fiber. Along the way, there have to be a means of ensuring minimal signal weakening and distortion. On the receiving end, there is the reception of the optical signal and a subsequent conversion back to an electrical form. The other fundamental fiber optic applications include the fiber lasers and optic sensors.
HISTORY OF EVOLUTION:
Jacques Babinet and Daniel Colladon discovered fiber optics through refractive light guidance in Paris in the 1840s. John Tyndall illustrated the same concept twelve years later in a London’s public lecture. He later wrote about the characteristics of total internal reflection of light in his book on introduction to the nature of light in 1870. Tyndall argued that whenever light ray crosses from air to water, it bends away from normal. The vice versa is also true. He asserts that if the light ray’s angle is above 480, there can be a total internal reflection in the water. Tyndall came up with a parameter called the limiting angle of a medium. It refers to the limit for the commencement of a total internal reflection. After conducting an intensive research, he established that the limiting angle for water is 480 27’ while that of a flint glass equals 380 41.’ He found out that diamond’s limiting angle is equal to 230 42’.
Since the discovery of fiber optics, it has gained many transmission applications. For instance, NASA with the help of fiber optics in the television camera was able to send it to the moon. Although the use of cameras then was considered confidential, one had to acquire enough security clearance or be accompanied by someone with the right security clearance to be permitted to handle the cameras.Another application for the fiber optics is photonic-crystal fiber. The emergency of photonic crystal paved a way for the development of photonic-crystal fiber in 1991. Photonic-crystal fiber involves guiding light by diffraction from a periodic structure. Also, the first photonic-crystal fibers were made commercially available in the year 2000. The photonic-crystal fibers are known to carry higher power as compared to other types of fibers. Also, their wavelength-dependent property can be altered to improve its performance.
USES OF FIBER OPTICS:
A fiber optic cable is in high demand since it can find a wide range of industrial applications. Below are some of the principal uses of optical fibers in the various fields of use.
Medical field- Fiber optics guide the light used in the imaging tools. They also act as lases during surgeries.
Government/ Defense- the act as seismic hydrophones in SONAR applications. They are useful in wiring aircraft and submarine and other vehicle types. They also help in field networking.
Storage of data- they help in the storage and transmission of data.
Telecommunications- Optical fibers are useful for the purposes of information transmission and reception of data.
Networking- Optical fibers link servers and users in various network settings. As such, they increase the accuracy and speed of transmitting data.
Commercial/ industrial uses- they help to obtain images of areas that are hard to reach. They aid in wirings in cases where there is an EMI problem. They also serve as sensory objects in making temperature, measuring temperature, and automobile wiring in industrial setups.
CATV/ broadcast- cable companies use optical fibers in the wiring of HDTV, CATV, video-on-demand, the internet, and other uses.
They are used in imaging and lighting. They act as sensors for measuring and monitoring an immense range of variables.
Development and research- optical fibers help in the testing all through the industrial fields mentioned above.
PROCEDURES:
AUDIO SIGNAL TRANSMISSION THROUGH FIBER OPTIC SYSTEMS:
Optical fiber is a transmission medium used in fiber-optic communication systems. A transparent and flexible filament that guides light signals from a transmission end to the reception terminal. Below is the circuit diagram of the Audio Signal Transmission through F/O. Let us assume the receiver is the 3 mm fiber optic cable.
The fiber consists of three major regions the core, the fiber’s center, actually carries the light. The cladding surrounds the core in a glass with a different refractive index than the core, allowing the light to be confined in the fiber core. A coating or typical buffer plastic provides strength and protection to the optical fiber
Effect of changes in receiver gains and Radio signal
The effect of the receiver gain & the sound through the speaker compared to the radio signal, the fiber optic cable made the sound clearer by transmitting the sound through the cable. The sound gain increases as the sound going through the speaker.
Distortion Effects observed
As the radio signal is pitched up, the frequency of the radio volume is fully blasting (becomes hazy) & as the coder is minimized, there is an increased touch in distortion.
What varies as sound information is transmitted?
The end of a fiber optic cable is set up with red color (that is, with the same color as LED which is on). This process also shows that the sound can travel from one medium to another.
What is modulated by the signal of the sound?
A carrier signal, which is a steady waveform, can be modulated by the sound signal. The carrier signal can be varied by both the amplitude modulation and frequency modulation. Information can be added to the carrier by varying the amplitude, the frequency, and the phase. Also, information can be added to the carrier by varying the polarization for optical signals. Here the volume on both receiver & the radio signals are the modulating factors
2. FIBER OPTIC LIGHT SENSING SYSTEM
Fiber optic sensors have immunity to electromagnetic interferences and do not conduct electricity. Hence, they are applicable in places with high voltage electricity or flammable material such as jet fuel. Fiber optic sensors can be designed to withstand high temperatures as well.
Point sensors: the measurement is carried out at a single pointing space, but multiple channels for addressing multiple points.
As sound information is transmitted, the below components vary (Q9-Q13)
For incandescent light-less distorted, less regulated & less constant
As frequency decreases, amplitude of the wave decreases and vice versa (for less distorted)
For less regulated signals (As frequency decreases, amplitude of the wave decreases and vice versa.
As frequency decreases, the amplitude of the wave decreases and vice versa (for less constant signals). Time scale=3 mins.
In respect to timeas time increases both amplitude & decreases. **frequency lower in generator & oscilloscope
Length- As the length increases, both the fiber optic amplitude and frequency of both decreases.
Q-14
As the LED's are turned on & off rapidly, at 43HZ of oscilloscope trace, the light stops blinking as the frequency is higher in oscilloscope than before
Q-15
At this point of the stage, there is a very slow sound generating from the system.
Q-16
When we put an object between the source & receiver, there is a sound, but when we are putting a paper, there is almost no sound.
Q-17
When we put a paper & increases the sound frequency, there is no sound.
Q-18
When we put plastic between the source & receiver, there is a more sound.
Q-19
When we put a black paper between the source & receiver, there is no sound as light cannot pass through it but passes through a white paper.
Q-20
3 mm is the max sound that is expected when it touches the reflectors, and it becomes quite again.
Q-21
Yes.
Q-22
It has to be a closure
3) FIBER OPTICS SOURCES AND LIGHT ATTENUATION IN FIBERS:
Optical light sources convert electrical signals to optical signals. It also launches the signals effectively.
Commonly used light sources include LEDs, SLEDs, ELEDs, and LDs.
LEDs produce nonlinear incoherent light whereas a Laser Diode produces linear coherent light.
Incoherent light sources used in multimode systems as where Laser Diodes/Tunable Lasers in single mode systems
Laser diodes must operate above their threshold region to produce coherent light, otherwise operating as ELED.
Laser diodes are much faster in switching response than LEDs
Tunable laser can produce coherent light output with controlled variable wavelength
Tunable laser is used in multi-wavelength systems by replacing a system where many sources are coupled to a multiplexing device system
FIBER OPTICS PRODUCTS:
Optical fiber cables
Optical Fiber Connectors
Optoelectronic devices like light emitting diodes, laser diodes, and modulators
Optical fiber fuse
Chromatic dispersers
The loss of intensity of light using optical fibers of various lengths was calculated, and the following answers were obtained:
Q11) v1=150, v=10, sound decreases
Q12) from fig 12 decreases and fig 13 increases
V= 210=> 1 m v= 202 => 3 m v=218 =>5 m
Sound increased from the speaker
Q13) more sound came from 5 m
PLOT OF SIGNAL STRENGTH VS FIBER LENGTH:
Works Cited
"Addison Technical Lib - Optical Fiber Cabling FAQ". Addison-cables.com. 2015. Merchants Industrial Centre, Mill Lane Laughton, Lewes, East Sussex, BN8 6AJ, UK. Retrieved from: http://www.addison-cables.com/product/Technical%20Lib/Optical%20Fiber%20Cabling.htm
Buck, John A. Fundamentals of Optical Fibers. Hoboken, NJ: Wiley-Interscience, 2004. Print.
Ghatak, Ajoy K, and K Thyagarajan. Introduction to Fiber Optics. Cambridge: Cambridge Univ. Press, 1998. Print.
Gupta, S C. Textbook on Optical Fiber Communication and Its Applications. New Delhi: Prentice-Hall of India, 2004. Print.
Pedrotti, Frank L, Leno M. Pedrotti, and Leno S. Pedrotti. Introduction to Optics. New Delhi: Pearson, 2012. Print.
