Photonics

Photonics is a specialty where light is the center of interest, in its wave or corpuscular form. Photonic solutions are essential in an immense number of fields, such as high-speed telecommunications, medicine, aeronautics, lighting, the environment (observation, processing), defense (night vision, guidance), metrology, etc. Within the framework of the EEA degree and this module, which is both practical (practical work) and theoretical (CM/TD), the basics of electromagnetism will be established, such as the propagation equation 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 allow us to understand how to use light for spectroscopic 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 to know how they behave, thanks to the manipulation of Maxwell's equations and the usual differential operators.

In a second step, the objective is to understand the phenomena of diffraction and interference, in order to be able to acquire the knowledge necessary to implement interferometers in the framework of usual applications in photonics such as spectroscopy, communications, measurements of deformations.

knowledge of waves (acoustic, microwave or other).

Recommended prerequisites: knowledge of geometrical optics.

1. I. Electromagnetic waves (CM7,5h - TD 3h)
2.  Reminders
3. Vector operators
4. Basic electrostatic/magnetostatic relations, fields and sources
5. Harmonic model of the plane wave
6. Maxwell's equations
7. Historical reminder
8. Description of Maxwell's equations
9. Linkage of MS to static relationships
10. Expression of EM in harmonic regime
11. Propagation of the electromagnetic field
12. Structure of the electromagnetic field
13. Propagation in vacuum, propagation equation
14. (Propagation of potentials)
15. In LHI settings
16. Relationships at the interface
17. Polarization
18. Notion of light polarizations
19. Law of Malus
20. Reflection/transmission at the interface
21. (Fresnel formulas)
22. Electromagnetic energy
23. Energy transported by an electromagnetic wave
24. Poynting vector
25. Mean value of the Poynting vector and applications

1. II. Interferences & Diffraction (CM7,5h - TD3h)
2. Introduction : Interferences & Diffraction (1h30)

            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 (beat)
4. d) Interference between contra-propagating waves: longitudinal standing wave

            1.3 Typical approach to the study of interference and diffraction

1. a) Run difference and phase shift
2. b) Sum of the electric fields
3. c) Evaluation of the optical intensity
4. Interferences (3h)

            2.1 2-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 (3h)

            3.1 Near field & far field

            3.2 Diffraction by a slit in the far field

            3.3 Far field Fourier transform

            3.4 Diffraction through a hole

            3.5 Young's fissures

            3.6 Diffraction grating

III. PRACTICAL WORK (12h)

            TP1. Polarization & Diffraction of light

            TP2. Mach-Zehnder amplitude modulator for optical communications

            TP3. Grating spectrometer

            TP4. Detection of weak optical signals