Superconducting Phenomena and Photonics
Superconducting Phenomena
- Definition: The ability of certain materials to conduct electric current with zero resistance below a critical temperature.
- Critical Temperature (Tc): The temperature below which a superconductor exhibits superconductivity.
- Critical Magnetic Field (Hc): The maximum magnetic field a superconductor can withstand while maintaining its superconducting properties.
Meissner Effect and Perfect Diamagnetism
- Meissner Effect: Expulsion of magnetic flux from the interior of a superconductor when it transitions to the superconducting state.
- Perfect Diamagnetism: Complete exclusion of magnetic fields from the interior of a superconductor in the superconducting state.
Types of Superconductors - Type I and Type II
- Type I Superconductors: Exhibit a single superconducting phase and complete Meissner effect.
- Type II Superconductors: Undergo a mixed state of normal and superconducting phases and allow the penetration of magnetic flux lines.
BCS Theory (Qualitative)
- BCS Theory: Bardeen, Cooper, and Schrieffer theory explaining superconductivity based on the formation of Cooper pairs of electrons.
High-Temperature Superconductors - Applications of Superconductivity
- High-Temperature Superconductors (HTS): Materials with higher critical temperatures compared to conventional superconductors.
- Applications: Magnetic resonance imaging (MRI), maglev trains, power transmission, and sensitive instrumentation.
Introduction to Photonics - Photonic Devices - Light Emitting Diode
- Photonics: The study and application of generating, controlling, and detecting photons.
- Light Emitting Diode (LED): A semiconductor device that emits light when an electric current is applied.
Photo Detectors - Junction and PIN Photodiodes
- Photodetectors: Devices that convert light signals into electrical signals.
- Junction Photodiode: A semiconductor device where light-generated electron-hole pairs contribute to a photocurrent.
- PIN Photodiode: Photodiode with a p-type/intrinsic/n-type structure for improved sensitivity.
Solar Cells - I-V Characteristics
- Solar Cells: Devices that convert sunlight into electrical energy.
- I-V Characteristics: Current-voltage characteristics that describe the performance of a solar cell under different conditions.
Optical Fiber - Principle of Propagation of Light
- Optical Fiber: A thin, flexible strand of glass or other transparent material used for transmitting light signals.
- Principle of Propagation: Total internal reflection, where light remains within the core of the fiber due to the higher refractive index.
Types of Fibers - Step Index and Graded Index Fibers
- Step Index Fiber: Optical fiber with a uniform refractive index throughout the core.
- Graded Index Fiber: Optical fiber with a gradually changing refractive index from the center to the outer cladding.
Numerical Aperture - Derivation
- Numerical Aperture (NA): A dimensionless number that characterizes the range of angles over which the fiber can accept or emit light.
- Derivation: Mathematical derivation of NA involves the refractive indices of the core and cladding.
Fiber Optic Communication System (Block Diagram)
- Fiber Optic Communication System: Communication system using optical fibers for transmitting data.
- Block Diagram: Illustration of the key components in a fiber optic communication system, including a transmitter, fiber optic cable, and receiver.
Industrial, Medical, and Technological Applications of Optical Fiber
- Industrial Applications: Sensing, monitoring, and control in industrial processes.
- Medical Applications: Endoscopy, imaging, and laser surgery.
- Technological Applications: Data transmission in telecommunications, internet, and networking.
Fiber Optic Sensors - Intensity Modulated and Phase Modulated Sensors
- Fiber Optic Sensors: Devices that use optical fibers to measure physical or chemical properties.
- Intensity Modulated Sensors: Measure changes in light intensity for sensing.
- Phase Modulated Sensors: Utilize changes in the phase of light for sensing applications.
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