The increasing demand for ubiquitous and extremely large bandwidth access to the network calls for the wider deployment of optical solutions not only as a mean of direct connection between the users, but also for the interconnections among wireless - thus microwave – systems.
Optical devices are therefore becoming key elements in every modern communication system. This Course aims at providing a deep understanding of their working principle, with a clear focus on applications. The acquired knowledge and skills will be useful not only in designing innovative optical telecommunication systems, but also in other rapidly growing areas of Photonics, such as those of optical sensors and of industrial laser machining. The course is taught in English.

At the end of the Course the students are expected to demonstrate the following main points of knowledge:
- understanding of the theory, and the experimental evidence in support, which underpin the mathematical models of the main optical devices;
- understanding of the main methodologies to analyse the behaviour of the most common optical and optoelectronic components used in communication systems and in other application domains of Photonics;
and the following skills:
- identification of the strengths and weaknesses of commercial devices;
- ability to propose different approaches to design new optical components;
- ability to present, in both oral and written forms, a clear and well-structured set of relevant considerations on design assumptions and results;
- ability to read, understand and comment technical material about optical devices from books, manuals, data-sheets, and any other source.

Key notions typically learned in basic courses on applied electromagnetism, such as transmission line theory, modes and principle of operation of metallic waveguides, and plane waves.

• Discrete optical devices (2.5 CFU)
o Reflection and refraction of plane waves.
o Multi-layered dielectric structures.
o Application to the design of anti-reflection coating, beam splitters, interferential filters, waveplates, isolators and circulators, etc.
• Dielectric waveguides (2.5 CFU)
o Analysis of dielectric waveguides.
o Modes of optical fibres: propagation in single mode and multimode optical fibres.
o Introduction to the fabrication and characterization of guided wave devices.
o Examples of devices: couplers, power splitters, fibre Bragg gratings, etc.
• Active devices (1 CFU)
o Devices in active optical waveguides: fibre amplifiers and lasers.
o Main characteristics of laser diodes.

The Course includes lectures on the theory, solution of exercises and experimental demonstrations. As the main goal is to provide the background and methods to understand how to design new components and critically analyse the performance of existing commercial devices, the theoretical derivations are aimed at studying real devices. As for the specific of the exercises, they are integrated in the lectures and deal with the design of simple devices covering subject matter described in the preceding lessons. Experimental demonstrations are carried out by the instructor or by small groups of students, depending on the availability and the complexity of use of the specific equipment required.

• Instructor’s notes.
• To probe further it may be also useful to consult:
o K. Iizuka, “Elements of Photonics” vol. I + II, Wiley.
o R.G. Hunsperger, “Integrated optics: theory and technology”, Springer-Verlag.
o W. Snyder, J.D. Love, “Optical waveguide theory”, Chapman and Hall.
o L.A. Coldren, S.W. Corzine “Diode Lasers and Photonic integrated Circuits”, Wiley.
o M.Fukuda “Optical Semiconductor Devices” Wiley.
o B.E.A. Saleh, M.C. Teich, “Fundamentals of Photonics”, Wiley.

The exam aims at assessing the specific knowledge of the topics listed in the Course program and the ability to apply the theory and its various methods for the solution of simple design projects. Following this approach, the exam, which is only oral, includes a discussion of the topics presented during the lectures and the presentation of the outcomes of some design assignments given during the Course. It usually lasts from 30 to 50 minutes. In more detail, the students are offered two grading paths: a “medium/high path” and a “top path”. Both require answering to 4-5 questions taken from a list published on the Course web-portal a couple of weeks before the end of the lesson period; then, the medium/high path further requires presenting the results of three design assignments, whereas the top path the results of five design assignments. The maximum mark achievable with the medium/high path is 27/30.