• 096059 - MICRO AND NANOOPTICS [1]

The Aim of the course is threefold: (i) to introduce the student to the theoretical foundations and main applications of Integrated Optics; (ii) to provide the student with a set of advanced tools and methods for the design and quantitative description of optical components and devices at the microscale; (iii) to give the student the theoretical basis for the understanding of highly innovative topics in modern Photonics.

- Knowledge and understanding (DD1)

• The student understands the physical basis of guided wave optics and of the optical phenomena taking place at the microscale.
• The student knows the guidelines for the modelling and design of integrated devices.
• The student is aware of the key functionalities implemented in micro and integrated optics.

- Apply knowledge and understanding (DD2)

• The student is capable to understand and solve simple problems in integrated and telecom optics and guided-wave photonics
• The student is capable to draft a quantitative design of integrated optics devices (couplers, filters, multiplexers and demultiplexers) that fulfil given target specifications.

- Making judgements (DD3)

• The student has the ability to understand the operating principles of optical devices at the microscale and to discuss the validity limits of the models used for their description.
• The student is capable to perform comparative analysis of different approaches to the achievement of a given optical functionality.

- Lifelong learning skills (DD5)

• The students knows the theoretical foundations and the main applications of integrated optics.
• The student masters a set of analytical tools and methods for the design and quantitative description of optical components and integrated optic devices.
• The student has the theoretical basis for the understanding of highly innovative topics in modern Photonics and for autonomously acquiring further knowledge in the field.

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

Concluding seminar on Silicon Photonics.

No pre-requisites, but the teaching makes use of the basic concepts of Optics and Electromagnetism.

Written examination, optionally followed by an oral examination.

The written exam consists of open questions: 3 questions to be solved in 2 hours and 15 minutes for students signed up for the full course of Micro and Nanooptics, 2 questions to be solved in 1 hour and 45 minutes for students signed up only for the course of Integrated Optics (which corresponds to the first part of Micro and Nanooptics). At the discretion of the student, the written text is followed by an oral test. The aim is to ascertain:

• the understanding of the physical basis of the optical phenomena at the microscale;
• the knowledge of the definitions, theorems and general concepts dealing with optical waveguides and integrated optics telecom components;
• the capability to discuss, both qualitatively and quantitatively, the performance of prototypal microoptical devices as a function of their key parameters.