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IMPORTANT CONCEPTS IN FIBER OPTICS

UNIT I 1.Elements of fiber optic communication https://www.youtube.com/watch?v=dbHxI43z75U 2.Total internal reflection,Critical angle,numerical aperture and Acceptance angle https://www.youtube.com/watch?v=og_eXK2JoT4 https://www.youtube.com/watch?v=q37CpocWZyw 3.Types of fibers and their comparisons-singlemode,multimode,step index and graded index https://www.youtube.com/watch?v=KW3HSJthFws https://www.youtube.com/watch?v=4fJPduWQ3u4 UNIT II 1.Scattering losses and bending losses(micro and macro bending) https://www.youtube.com/watch?v=ZgeYdYPhF9A https://www.youtube.com/watch?v=ZcQsaF-sps8 2. Intermodal and intramodal dispersion https://www.youtube.com/watch?v=8oRaDSD0MDA 3.Pulse broadening in graded index fibers https://www.youtube.com/watch?v=MdpemgPmeAU 4.Mode coupling https://www.youtube.com/watch?v=-dV9o-O9Dqs Unit III 1.Surface emitting LED and Edge emitting LED https://www.youtube.com/watch?v=DBrQqy2tuq8 https://www.youtube.com/watch?v=PHkFMUHBtLU 2.PIN and Avalanche Photo dio...
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OPTICAL AMPLIFIERS

  An Optical Amplifier amplifies optical signal without converting it to electronic signal They can be placed anywhere along the Optical length of the fiber They can be bidirectional Optical Multiplexing is possible They accept signals of different wavelength and provides Amplification They use Stimulated Emission like LASER .But Optical amplifiers do not have Feedback mechanism. All Optical Amplifiers have an Active medium.There is an external source called Pump to supply energy to the medium.This raises the electrons in the active medium to higher energy levels.The incoming photon from the signal(input signal which is to be amplified) will excite the electrons to lower energy level resulting in the emission of photons thereby amplifying the signal Applications of Amplifier In Line amplifier- They are used in between Transmitter and receiver to increase the distance between them Pre Amplifier-They are used before the receiver to improve its sensitivity Transmission Booster- If Opt...
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OPTICAL SWITCHING-SEED,Bipolar Controller Modulator

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 OPTICAL SWITCHING It is a process by which an optical signal can be routed to a desired communication path without converting them to electrical signal. There are two types of optical switches slow switch-used to route around a fault  in the optical fiber Fast Switch-uses Electro optic or magneto optic effect for switching There are 3 broad classification of  switches 1.Mechanical Method Mirrors and prisms are used to divert incoming optical signals to the required path. They can be controlled easily as they are simple in structure.Miniaturization and application in large scale communication equipment is difficult. 2. MEMS (Micro electro mechanical systems) The Mechanical components,sensors and actuators are fabricated on a silicon substrate.They are ideal for large scale switching.Their Power consumption is minimal.They need high processing capabilities for manufacturing. 3.Optical Wave guide Method These switches utilize the refractive index of substrates to guide opti...
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TUNABLE THRESHOLD LOGIC GATE-SWITCHING SPEED AND ENERGY

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  The below figure is the circuit diagram of an MQW-HBT 3 input threshold gate Figure 1 MQW-HBT 3 input threshold gate To operate the gate,the light should be above the excitonic peak The Load resistor current is the superposition of currents in the MQW-HBT P-i-(MQW)-n diodes in parallel with HBTs modulate light of the same wavelength In the figure,a load resistance is used with a variable voltage supply. A Zener diode is connected in parallel with the MQW-HBT. It prevents damage due to accidental high voltages. For the light source,a tunable laser is used. When there is no light on the MQW-HBT, there is no current and no voltage drop across the load The function of the gate can be altered by changing the supply voltage For a  NOR function, 12v power supply and when none of the inputs is 1(illuminated),the output is 1 and if any of the input is 0,the output is 0 For a Inverse Carry Gate, 18v power supply  and when two or more inputs are 1,the output is 0,else output is 1 ...
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OPTICAL MODULATORS

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 An Optical Modulator is used for modulating optical signal by changing the properties of light Depending on the properties of light changed,there are Intensity modulators,Phase modulators and polarization modulators. There are two types of modulation techniques for optical signals. They are  direct Modulation and External modulation Direct Modulation  Fig 1* The Message signal is Superimposed on the bias current which modulates the laser beam It causes issues like Frequency chirping,Pulse spreading and Loss of Information External Modulation Fig 2* The laser beam is modulated by an external optical modulator It is used in High end systems It is most complex and expensive  The below figure shows the classification of Optical Modulators Fig 3* Refractive Modulator-by varying refractive index of the modulating Material Absorptive Modulator-by varying absorption coefficient of the material *Figure courtesy:Google Images
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About Me

Finally,My dream of owning a blog came true.I have been contemplating so long to continue my passion for writing, since my school days.I have henceforth no space in my little brain and heart to have all my technical and societal laments stuffed up.So,decided to spill it out in this blog of mine😁 I am an avid reader and dreamer.I read all kinds of books and even in different languages.You may wonder how but that's an another topic for my blog😉..I am Lazy and active,Introvert and extrovert, smart and stupid  at the same time..Technically,I am always in Quantum superposition state😎.Apart from reading,dreaming and writing,I love to talk..and that's how I chose my Profession Professionally,I am an assistant Professor at SRMIST,Chennai.My research Areas are Computer vision and Artificial Intelligence.I also love to work in Cloud Computing, IOT, Big data Analytics,Cryptography and Quantum Computing(Remember,I am always in Quantum superposition😆)
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