Learning outcomes of the course unit
1. Knowledge and understanding
The course gives an understanding of fiber optic technology and its related devices for WDM telecommunication systems. The most important devices, as lasers, optical amplifiers, photoreceivers, couplers, gratings are deeply analyzed.
New approaches and analysis tools will be provided as long as important novelty in the field of photonics and optoelectronics.
2. Applying knowledge and understanding
- analysis and description of the architecture of an optical fiber telecommunication system;
- evaluate the main characteristics and specifications of the main photonic devices;
- find the solutions for the Project of optical fibers and photonic devices for several applications.
Course contents summary
The course gives an understanding of fiber optic technology and its related devices for WDM telecommunication systems. The main devices as lasers, optical amplifiers, optical couplers, gratings will be deeply analyzed. 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 cladding dimensions.
• 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 diodes (LEDs) and Lasers. 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 dielectric 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.
• The finite element method.
S. Selleri, L. Vincetti, A. Cucinotta, "Componenti ottici e fotonici ", Società Editrice Esculapio, 2012
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.
Lessons will be given by the teacher on the blackboard as well as by multimedia presentations. Classroom exercises will be carried out in preparation of the exam. More than 10 hours will be reserved for experimental laboratory activities and the training in the use of commercial software.
Assessment methods and criteria
A written exam and an oral examination. The written exam consists of open questions.
During the lesson period there will be two written tests, if the student passes these tests, he/she will be exempted from the written exam.
The written exam will test a candidate's knowledge of measure units, basic theory and design principles. The oral exam assesses a candidate's understanding of the main parameters and principles in the areas of optical waveguides, fiber optics, photic components. This exam combines in-depth technical concepts with design principles.
The educational material is available at the web site gaem.tlc.unipr.it