MICRO AND NANOOPTICS
Aim of the course is the study of the theoretical foundations and of the main applications of Integrated Optics, Microoptics and Nanooptics.
SYLLABUS - MICRO AND NANOOPTICS :
Introduction to optical communication systems.
Historical evolution. Introductory concepts: analog and digital transmission, multiplexing techniques, modulation formats. Layout of an optical communication system: topology, design criteria, integrated optical devices. Analysis of the bit-error-rate as a function of the main noise system sources. Communication systems limited by attenuation and dispersion.
Integrated optical devices.
Couplers and power splitters in integrated optics.
Coupled mode theory. Transfer matrix of the directional coupler. Functional analysis of the directional coupler as a 3-dB coupler, as a frequency filter and as an optical switch. Other types of couplers and beam splitters: the bifurcation, the multimode interference coupler, the star coupler.
Optical filters in integrated optics.
FIR (Finite Impulse Response) and IIR (Infinite Impulse Response) filters. General spectral properties of filters. Mach-Zehnder interferometer: spectral response and engineering guidelines. The Arrayed Waveguide Grating (AWG): operation principle, transfer function, engineering guidelines. Functional analysis of the AWG as a de/multiplexer, as a router and as a reconfigurable add-drop filter. Ring resonant filter: transfer function and main features.
Electro-optic intensity modulators.
The electro-optic effect: basic principles. X-cut and Z-cut lithium niobate modulators. Lumped and travelling electrodes. Bandwidth limitations. Integrated optical intensity modulators: architectures (Mach-Zehnder interferometer, directional coupler, deltabeta-reversed directional coupler) and performance. Comparison with bulk modulators.
Recent advances in the field of optical communications.
DPSK modulation formats: signal to noise ratio and architecture of transmitters and receivers. Coherent detection and digital signal processing for multi-level transmission formats and dispersion compensation.
Concluding seminar on fabrication techniques, packaging issues and new technological perspectives.
SYLLABUS - MICRO AND NANOOPTICS :
Electromagnetism as an Eigenvalue Problem: Electromagnetic Harmonic Modes, Symmetries and Classification of Harmonic Modes, Variational Principle in Electromagnetism, Scaling Properties of Maxwell's Equations. Wave propagation in homogeneous and inhomogeneous media: Angular Spectrum Representation, Scalar Diffraction Theories, TE-TM Decomposition, Evanescent waves.
Optical functions and their implementation. Classification of Microoptical Elements. Refractive Microoptics: Profiled microlenses and their applications, Gradient-index (GRIN) microoptical elements (fiber/rod microlenses), Paraxial approximation (the optical Schrodinger equation), Applications of parabolic GRIN fiber/rod microlenses. Introduction to diffractive microoptical elements: kinoform microprisms and microlenses.
Generalities on periodic lattices. Bloch Electromagnetic Theorem. Photonic Band Structure.
One-dimensional PCs: Periodic Layered Media, Band States and Gap States, Surface States and Bulk Defect States, Applications to Bragg Reflectors and Filters, Omnidirectional Dielectric Mirrors, Photonic Bragg Fibers. Two-dimensional PCs: A polarization-indepenendent band-gap, Point and Line Defects and application to PC cavities and waveguides, Out-of-plane propagation, PC fibers. PC Interfaces: Negative Refraction, Superlens and Superprism Effects.
Near-field Optics and Plasmonics.
The diffraction limit to optical imaging. From the far-field to the near-field. The near-field microscope and its applications.
Aims and methods of Plasmonics. Optical properties of noble metals. Surface Plasmon Polaritons (SPPs): Derivation of the SPPs dispersion equation, Optical properties of SPPs, Excitation and detection of SPPs, Plasmon-Polaritons in thin metallic films (SR/LR-SPPs), Introduction to plasmonic waveguides. Localized plasmons (LPs): Quasistatic theory of localized plasmonic resonances in noble metal nanospheres, Optical properties of metallic nanoparticles (resonant polarizability, absorption and scattering cross-sections, field-enhancement, resonance tuning), Introduction to plasmonic nanosensing (SPR and SERS).