Objectives of the course
The objective of the course is to give an understanding of fiber optic technology and its related devices for WDM telecommunication systems. New approaches and analysis tools will be provided as long as important novelty in the field of photonics and optoelectronics.
• Simmetric slab.
• Optical fiber. Numerical aperture. V-number. Fractional refractive index difference. Step-index fiber. TE, TM, EH e HE guided modes. Weakly guiding fiber. LP guided modes. Power confinement factor and its dependence on V-number. Gaussian approximation: spot size and mode field diameter. Graded index and matched cladding fibers.
• Fiber trasmissive properties: attenuation. Intrinsic and extrinsic attenuation causes. Rayleigh scattering. Macro and micro-bending losses. Ultra violet and infra-red absorption. Data sheets of commercial fiber types.
• Fiber trasmissive properties: dispersione in fibra. Intermodal and Intramodal dispersion. Cromatic Dispersion. Dispersion Shifted Fibers (DSFs), Non-Zero Dispersion Shifted Fibers (NZDSFs), Dispersion Compensating Fibers (DCFs). Example of a DCF design.
• Plastic optical fibers: material, attenuation, core and del cladding diamaters.
• Optical amplification principles. Population rate equations. Four, three and two levels systems. Propagation rate equations. Absorption and gain coefficient.
• Rare earth doped fiber amplifies. Design, schemes, forward and backward pumping, gain, noise figure. Evolution of signals, pumps and ASE powers along the fiber.
• C, L, and S band optical amplification. Silicate, tellurite and florurate fibers. Fiber lasers.
• Semiconductor optical amplifiers.
• Light emitting diode (LED) e Laser. Designs and physical operation principles.
• Single longitudinal mode lasers. DFB e DBR. Tunable lasers..
• Vertical Cavity Surface Emitting Lasers (VCSELs) Performances and advantages.
• Receivers. Photodetectors.
• Photodiodes. PIN, Avalanches photodiodes. Noise sources.
• Passive Components. Couplers/splitters. Wavelength Division Multiplexers and Demultiplexers (WDM MUXs/DEMUXs). Isolators, Circulators and Attenuators.
• Bragg gratings in optical fiber and dielectric waveguide. Couple mode theory. Applications to reflectors, wavelength selectors, dispersion compensation, add-drop filters.
• Directional couplers in optical fiber and dielectrid waveguide.
• Reflection gratings. Optical spectrum analysers. Fabry-Perot cavity. Interferometers.
• Mach-Zehnder interferometer filters. Splitters and star-couplers, multiplexer and demultiplexer. • Plane waves in anisotropic media; ordinary and extraordinary waves. Magneto-optic devices, phase retarders, polarizers, isolators and circulators; applications.
• Optical modulators. Electroabsorption, electrooptic and acustooptic modulators. Applications; optical switches, wavelength converters.
• Photonic crystals and band gap. Definition, technology and structures.
• Photonic crystal based devices: waveguides, junctions, curves, filters, couplers.
• Photonic crystal fibers and holey fibers. Definition, fabrication technology, applications in telecommunications; performances. Source coherence; spatial and temporal coherence.
• Finite Methods; the finite difference and the finite element method, the mode matching.
Student can attend labs for numerical simulations and experimental activity.
D.K. Mynbaev, L.L. Scheiner, "Fiber-Optic Communications Technology“, Prentice Hall, 2001.
P. Bassi, G. Bellanca, G. Tartarini, "Propagazione ottica libera e guidata" Clueb, 1999.
J. M. Senior, “Optical Fiber Communications”, Prentice Hall, 1992
Slides (Materiale Didattico)