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Fundamentals of Photonics

or Introduction to Lightwave Technologies (ILT)

This course is offered each Spring semester by the Department of Electrical and Computer Engineering at Aarhus University, as part of its comprehensive Photonics Teaching Program.

Overview

Watch a brief introduction to the course in this 1-minute video: MP4

Purpose of the course

This course provides students with a solid foundation in the principles and applications of photonics. By covering essential topics such as electric and magnetic fields, light propagation, optical fibers, and photodetection, this course prepares electrical engineering students to tackle cutting-edge challenges in telecommunications, medical imaging, and quantum computing. It combines theoretical knowledge with practical lab exercises and offers networking opportunities with industry leaders. This course opens up new avenues for innovation and career opportunities in high-tech industries.

Learning outcome

  1. Master photonic basics: Gain a thorough understanding of light propagation, modulation, and detection.
  2. Hands-on experience: Work with cutting-edge photonic devices, including optical fibers and photodetectors.
  3. Systems integration: Learn to design and analyze complex photonic systems, enhancing your problem-solving skills.
  4. Innovative design: Develop the ability to create novel photonic solutions for advanced applications of industrial relevance.
  5. Research skills: Engage in independent thinking, exploring the latest advancements and challenges in the future of optical technologies.

Academic content

The course covers the fundamental principles and applications of photonics. Key subjects include:

  • Basics of photonics: Explore the basics of electric and magnetic fields, and the propagation of light.
  • Core optical components: Study of the working principles of lasers, waveguides, and photodetectors.
  • Light modulation: Learn advanced techniques for modulating light for various applications.
  • Integrated photonics systems: Design and analysis of photonic circuits and systems.
  • Real-world applications: Discover how photonics revolutionizes telecommunications, medical imaging, and quantum computing.
  • Hands-on lab work: Gain practical experience with state-of-the-art photonic devices and systems.

ECTS credits: 5

Course coordinator: Nicolas Volet

Program requirement: Active participation is mandatory.

Prerequisites: Prior knowledge of electromagnetism and optics.

Course assessmentEvaluation will be based on an oral exam, centered on a design study you will develop, incorporating one or more research papers related to lightwave technologies. Grading will follow the seven-point scale and will include an external co-examiner.

Next edition

During the Spring semester: January – May2025.

Part 1

1. Electric and magnetic fields

Jan. 29 + Feb. 1
Recap on complex numbers and differential operators.
Maxwell's equations and complex fields.
Fourier decomposition, separation of variables and trial solution.
Pulses, small-signal modulation and continuous-wave (cw) operation.
Wavenumber, attenuation coefficient and effective refractive index. 
Expressions for the electric field.

  • Solutions: PDF

2. Direction of propagation

Feb. 5 + 8
Constitutive relations. Helmholtz’ equation. 
Relative directions of the fields.
Poynting vector, time average.
Intensity and optical power.
Walk-off effect.
Boundary conditions. Snell's law.
Total internal reflection. Evanescent field.

  • Solutions: PDF

3. Interface between materials

Feb. 12 + 15
Transverse polarizations.
Coefficients of reflection and transmission.
Fresnel's relations.
Brewster's angle. Phase jumps.
Thin films: antireflection (AR) coating, bandpass filter, distributed Bragg reflector (DBR).
Goos-Hänchen effect.

During the exercice session on Thursday (Feb. 15), we will use the software EMode Photonix.
Information on how to get started can be found here.
Please go through the information provided at this link and install the license.

  • Solutions: PDF

4. Gaussian waves

Feb. 19 + 22
Dispersion relation and paraxial wave equation. Material refractive index.
Gaussian solution. Rayleigh length. Beam waist and divergence. Gouy's phase.
Effective beam area. M-squared parameter.

  • Solutions: PDF

5. Generation of light

Feb. 26 + 29
Incandescence and blackbody radiation.
Planck's spectrum, Wien's law.
Foundations of quantum mechanics.
Spontaneous and stimulated emission.
Wavelength conversion.

  • Booklet: TBC
  • Slides: PDFPPT
  • Exercises: PDF
  • Solutions: PDF

National Optics Congress in Odense: Feb. 27 + 28
Great opportunity to network with #photonics companies on the beautiful campus of University of Southern Denmark (SDU).
––> For students: all expenses paid for the conference experience including transport and accommodation.


6. Wavelength conversion

March 4 + 7
Second-harmonic generation.
Optical frequency combs.

––> March 8 (Friday): deadline to submit group abstracts

  • Solutions: PDF

Guest lecture from Asger Sellerup Jensen, Senior Market Development Manager & Head of Quantum at NKT Photonics
Video: MPG


Internship and Project Day: March 8 (Friday)
Starting at 7:45 in Building 5122, Room 122.
See this LinkedIn post.


7. Optical spectrum

March 11 + 14
Ensemble average. Wiener-Khintchine theorem.
Phase noise, frequency noise and intrinsic linewidth.
Lorentzian spectrum of an ideal laser.
Flicker noise and dither tones.

––> Feedback on submitted abstracts

  • Solutions: PDF

7b. Polarization of light

Polarization ellipse. State of polarization.
Stokes parameters.
Polarizers and waveplates.
Müller matrices.

  • Booklet: PDF
  • Slides: PDFPPT
  • Exercises: Lab session

8. Modes in optical fibers

Part 1: March 18 + 21
Dispersion relation.
Characteristic equation and effective index.
Single-mode condition.

  • Solutions: PDF

Research Day: March 20 (Wednesday)
Pitches starting at 12:30 in Peter Bøgh Andersen Auditory in Building 5335.
Poster session starting at 13:30 in Building 5122, Room 122.


Introduction to Integrated Nonlinear Photonics (March 22)


March 25 – 29: no teaching at AU (Easter)

Part 2

** April 1 (Monday): public holiday (Easter Monday), no teaching **

––> April 4 (Thursday): group presentations


9. Modes in optical fibers

Part 2: April 8 + 11
Intensity distribution.
Hybrid modes.
Electric mode profiles.

––> April 12 (Friday): deadline to submit individual abstracts

  • Solutions: PDF

Introduction to Photodetection (April 11)


10. Multiplexing

April 15 + 18
Wavelength division multiplexing (WDM).
Splitters and combiners.

––> Feedback on submitted abstracts: PDFPPT

  • Booklet: TBC
  • Slides: PDFPPT
  • Exercises: PDF
  • Solutions: PDF

11. Directional couplers and interferometers

April 22 + 25
Directional couplers and supermodes. Phase-matching condition.
Mach-Zehnder interferometers (MZIs).
Multi-mode interference (MMI) couplers.
Optical hybrids and coherent receivers.

  • Solutions: PDF

12. Ring resonators

April 29 + May 2
Transmission spectrum. Critical coupling.
Quality factor. Effective phase shift.
Applications: filters, mirrors, isolators, optical frequency combs, and all-optical switches.

Teacher: Pedro

  • Solutions: PDF

13. Phase modulation

May 6
Electro-optic effects. Pockels cells.
Electro-optic modulators (EOMs). Generation of sidebands.

** May 9 (Thursday): public holiday (Ascension Day), no teaching **

  • Booklet: PDF
  • Slides: PDF – PPT
  • Exercises: TBC

14. Last session

May 13 + 16
Recap.
Course evaluation

––> May 16 (Thursday): individual presentations (rehearsal)

Simulation exercises

For numerical simulations of modes in waveguides, we will use the software EMode Photonix.
Information on how to get started can be found here.


Exam:

The evaluation is based on an oral exam, which will focus on a design study you will make involving one or more research papers related to optical technologies.

  • April TBC (Friday): deadline to submit your abstract (100 words)
  • May TBC (Thursday): individual presentations (rehearsal)

For those that would like to attend the exam, please send your abstract to Nicolas Volet by email before the above deadline.

The exam is oral, and the duration is 20 min.
We ask you to prepare a presentation for 10 min, leaving 10 min for questions.


Storage

LaTeX files (for booklets and exercises) are available at this Overleaf project.

Slides and other files are available at this SharePoint site.