Unit - I
Overview of optical fiber communication : The general system, Advantages of optical fiber communication. Optical spectral band.
Optical Fiber waveguides: Introduction, Ray theory transmission Total internal reflection, acceptance angle, numerical aperture, skew rays.
Electromagnetic mode theory for optical propagation : Electromagnetic waves, modes in a planar guide, phase and group velocity, phase shift with total internal reflection and the evanescent field, goos hanchen shift.
Unit - II
Cylindrical Fiber : modes, mode coupling, step index fibers Graded index fibers, Single mode Fiber: Cut-off wavelength, Mode field diameter and spot size, effective refractive index, Group delay and mode delay factor, The Gaussian approximation, equivalent step index methods.
Signal distortion in optical fibers - Attenuation, Material Absorption, losses in silica glass fibers; Intrinsic absorption, Extrinsic absorption. Linear scattering losses; Ray light scattering, Mie scattering.
Non linear Scattering losses : fiber bending losses;
Dispersion, Chromatic dispersion: material dispersion, waveguide dispersion. Intermodal dispersion: Multimode step index fiber, Multimode graded index fiber.
Overall fiber dispersion Multimode fiber, Dispersion modified single mode fibers, Dispersion–shifted fiber, dispersion flatted fibers, nonzero-dispersion-shifted fibers (MZ-DSF),
Polarization : Fiber birefringence, polarization mode dispersion, polarization-maintaining fibers, Non linear effects: Scattering effects, Kerr effects.
Unit - III
Optical sources - Light Emitting Diodes (LEDs): Structures, light source materials, Quantum Efficiency on LED Power Modulation of a LED,
Laser Diodes - models and threshold conditions, laser diode rate equations, External quantum efficiency, resonant frequency, laser diode structures and radiation patterns, single mode lasers modulation of laser diodes, laser lines.
Unit - IV
Source to fiber power launching, Source Output patterns, Power coupling calculation, Power launching versus wavelength, equilibrium numerical aperture.
Photo detectors : Physical principles of photodiodes: The PIN photo detector, Avalanche photodiodes.
Photo detector Noise : Noise sources, signal to noise ration.
Detector Response time: Depletion layer photocurrent, response time structure of in GaAs APDs, Temperature effect on Avalanche gain, comparison of photo detectors.
Unit - V
Optical receiver operation : Fundamental receiver operation: Digital signal transmission, error sources, front end amplifier.
Digital receiver performance: Probability of error receiver sensitivity, The Quantum Unit.
Eye Diagram : Eye Pattern Features, BER and Q Factor Measurement Coherent Detection: Fundamental concepts, Homodyne detection, heterodyne detection, IBER comparisons.
Digital links : Point to point links, power penalties.