Photonics

Photonics is a specialty that focuses on light, in both its wave and particle forms. Photonic solutions are essential in countless fields, such as high-speed telecommunications, medicine, aeronautics, lighting, the environment (observation, treatment), defense (night vision, guidance), metrology, etc. As part of the EEA bachelor's degree and this module, which is both practical (laboratory work) and theoretical (lectures/tutorials), the basics of electromagnetism will be covered, such as the equation for the propagation of an electromagnetic wave, the properties of these waves, and their behavior at interfaces. This will lead to the study of key phenomena in wave photonics in particular, such as diffraction and interference, which will provide an understanding of how to use light for spectroscopy analysis, to measure deformations, to encode information for very high-speed communications, to store information, etc.

The objectives of this module are, first, to be able to describe electromagnetic waves and understand how they behave, using Maxwell's equations and standard differential operators.

The second objective is to understand the phenomena of diffraction and interference in order to acquire the knowledge necessary for implementing interferometers in common photonic applications such as spectroscopy, communications, and deformation measurements.

knowledge of waves (acoustic, microwave, or other).

Recommended prerequisites: knowledge of geometric optics.

1. I. Electromagnetic waves (CM7.5h - TD 3h)
2.  Reminders
3. Vector operators
4. Basic electrostatic/magnetostatic relationships, fields, and sources
5. Harmonic model of the plane wave
6. Maxwell's equations
7. Historical overview
8. Description of Maxwell's equations
9. Link between EMs and static relationships
10. Harmonic mode expression of EMs
11. Propagation of the electromagnetic field
12. Structure of the electromagnetic field
13. Propagation in a vacuum, propagation equation
14. (Propagation of potentials)
15. In LHI circles
16. Transition relations at the interface
17. Polarization
18. Concept of light polarization
19. Penalty Law
20. Reflection/transmission at the interface
21. (Fresnel formulas)
22. Electromagnetic energy
23. Energy carried by an electromagnetic wave
24. Poynting vector
25. Average value of the Poynting vector and applications

1. II. Interference & Diffraction (Lecture 7.5 hours - Tutorial 3 hours)
2. Introduction: Interference & Diffraction (1.5 hours)

            1.1 Huygens-Fresnel principle

            1.2 Different types of interference (stationary, instantaneous)

1. a) Description of light and formalism
2. b) Monochromatic interference
3. c) Instantaneous interference (beating)
4. d) Interference between counter-propagating waves: longitudinal standing wave

            1.3 Typical approach for studying interference and diffraction

1. a) Step difference and phase shift
2. b) Sum of electric fields
3. c) Evaluation of optical intensity
4. Interference (3 hours)

            2.1 Two-wave interference

1. a) Michelson interferometer
2. b) Transfer function of a 2-wave interferometer
3. c) Polychromatic interference 

            2.2 N-wave interference

1. a) Fabry-Perot cavity
2. b) Airy function
3. c) Fabry-Perot with gain (laser)

            2.3 Other common interferometers & applications

1. Diffraction (3 hours)

            3.1 Near field & far field

            3.2 Diffraction by a slit in the far field

            3.3 Fourier transform in the far field

            3.4 Diffraction through a hole

            3.5 Young's slits

            3.6 Diffraction grating

III. PRACTICAL WORK (12 hours)

            TP1. Polarization & Diffraction of Light

            TP2. Mach-Zehnder amplitude modulator for optical communications

            TP3. Grating Spectrometer

            TP4. Detection of weak optical signals