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Photonic Devices

Next edition

During the Fall semester: August – December2024.

Short introduction

A short overview of the course is provided in the following slides: PDFPPT

This course is taught during the Fall semester at the Department of Electrical and Computer Engineering of Aarhus University. It is part of the Photonics teaching portfolio.

Objectives of the course:

The objective of the course is to acquaint the student with the main photonic devices, their integration onto a photonic integrated circuit and the applications of this technology. This will be achieved by first introducing some fundamentals of light-matter interaction. Then an overview of the most important photonic devices will be presented. It will be discussed how these photonic devices can be considered as building blocks that can be combined into a circuit and which material systems can be used for that. Emphasis will be put on the required trade-offs and the main differences between material systems.

After this course the student should be familiar with the main photonic devices and the main platforms for photonic integration that are available. The student should be able to make a design study, with a qualitative understanding of the required trade-offs and a quantitative knowledge of the typical component and/or circuit operation parameters.

Learning outcomes and competences:

The participants must at the end of the course be able to:

  • explain the physics behind the selected photonic devices;
  • model a selected device and/or circuit in a design study;
  • explain how a photonic integrated circuit can be made and in which materials;
  • know which building blocks are available in each platform and know typical operating parameters;
  • discuss the trade-offs that have to be made when choosing a platform and designing a circuit.

ECTS credits: 10

Course coordinator: Nicolas Volet

Compulsory programme: Active participation.

Prerequisites: Electromagnetism, Optics.

Course assessment:
Oral examination based on written report. Design project with written report.
Seven-point grading scale. Internal co-examination.

Where and when?

  • At AU-ECE, Building 5125 ("Edison", Finlandsgade 22)
    Lectures: 
    – Mondays 14:15–16:00 in Room 430
    – Thursdays 12:15–14:00 in Room 423
    Exercises + lab demos: 
    – Thursdays 14:15–16:00 in Room 423

Course contents

This course addresses the core photonic engineering technologies such as diode lasers, optical fibers, and photonic integrated circuits, and their applications in communications, sensing and metrology. It is of interest to engineers who want to become active in the field of photonics, as well as to electrical engineers who want broaden their scope and anticipate on the exponentially increasing convergence of electronics and photonics.

The course will first introduce the fundamentals of light-matter interaction in semiconductors, focusing on effects like optical gain and absorption, light emission and optical waveguiding. The main electro-optic components, such as LEDs, laser diodes, modulators and detectors will be discussed. Finally it will be shown how these components can be combined into a photonic integrated circuit, also known as an optical chip. The main integration platforms, for example silicon nanophotonics and indium phosphide photonics, and their fabrication technology will be discussed. Applications of photonic devices and circuits in communications, microwave technology, and biomedical sensing and imaging will be reviewed.

The content of the course is summarized into several booklets. These booklets are meant to be concise and include all mathematical steps.

Part 1

1. Light-matter interaction (Aug. 26 + 29)
Introduction/overview.
Bandgap and semiconductors.
Generation of light. Spontaneous/stimulated emission.


2. PN junction (Sept. 2 + 5)
Recap on modes
PN junction

  • BookletPDF
  • SlidesPDF – PPT
  • Exercises: PDF – Solutions

3. Material platforms (Sept. 9 + 12)
Confinement of current + confinement of light
Materials for photonics

  • SlidesPDF – PPT
  • Exercises: PDF – Solutions

4. (Sept. 16 + 19)
Materials for photonics

*to update*––> Sept. 22 (Friday): deadline to submit group abstracts

  • SlidesPDF – PPT
  • Exercises: Group work for projects

5. Recombination processes (Sept. 23 + 26)
Growth. Lattice matching. Dislocations and quantum dots.
Dangling bonds and passivation.
Band structure.
Wafer fusion and heterogeneous integration.
Radiative recombination. Auger process. Phonons.

*to update*Sept. 25 (Monday): feedback on abstracts

  • Booklet: PDF
  • SlidesPDF – PPT
  • Exercises: Group work for projects

6. (Sept. 30 + Oct. 3)
Infrared C-band: 
scattering, attenuation and dispersion

Mid-infrared lasers:
quantum cascade lasers (QCLs) or difference-frequency generation (DFG)
HiTran database.

Deep-UV photonics:
Lasers, fibers and detectors
Nonlinear crystals and lithography

*to update*🍕––> Oct. 5 (Thursday) at 12:00: 
Pizzas and guest lecture from Peter Tønning, Senior System Engineer at UV Medico

  • SlidesPDF – PPT
  • Exercises: PDF – Solutions

7. Optical amplification (Oct 7 + 10)
Erbium-doped fiber amplifiers (EDFAs).
Wavelength division multiplexing (WDM).

*to update*––> Oct. 12 (Thursday): group presentations

  • SlidesPDF – PPT
  • Exercises: PDF – Solutions

*to update*Oct. 13 (Friday): R-Day starting at 13:00 at 5122-122
The R-day event is an open forum for engagement and discussions among researchers and students within ECE. It aims at creating awareness and promoting research activities.

Week 42 (Oct. 14 – 18): no teaching at AU.
Interested in Integrated Nonlinear Photonics?
Join us at EPFL (Lausanne, Switzerland) or online for a week. More info and registration (for free) at this link.

Part 2

8. Semiconductor optical amplifiers (Oct. 21 + 24)
Transverse confinement factor. Net gain and saturation.
Semiconductor optical amplifiers (SOAs). Small-signal gain factor.

  • Booklet: PDF
  • SlidesPDF – PPT
  • Exercises: PDF – Solutions

9. Laser performance (Oct. 28 + 31)
Condition for lasing threshold. Gain clamping.
Rate equations for the carrier and the photon densities.
Output power versus current.

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

10. Dynamics (Nov. 4 + 7)
Turn-on delay.
Small-signal modulation.
Wavelength chirp.

*to update*––> Nov. 8 (Wednesday): deadline to submit individual abstracts

*to update*Thursday (Nov. 9): Feedback on abstracts + exam preparation

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

11. Reflectors (Nov. 11 + 14)
Thin films and anti-reflective (AR) coatings.
Distributed Bragg reflectors (DBRs).
Corrugated waveguides.
Fiber Bragg gratings (FBGs).
Fabry-Perot interferometer and etalon.
Wavelength stabilization.

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

12. Narrow-linewidth lasers (Nov. 18 + 21)
Intrinsic linewidth and coherence length. 
Fiber lasers.
Optical feedback.
External-cavity diode lasers (ECDLs).

*to update*––> Nov. 20 (Monday) at 10:15:
Guest lecture from Asger Sellerup Jensen, Senior Market Development Manager & Head of Quantum at NKT Photonics
Video: MPG

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

13. Pulses and incoherence (Nov. 25 + 28)
Speckle effect.
SLEDs: superluminescent light-emitting diodes.
Optical gyroscopes.

Isolators and circulators.
Stabilization loop: Pound-Drever-Hall (PDH) method.

*to update*––> Nov. 30 (Thursday): deadline to submit intermediate individual reports


14. Phase modulation (Dec. 2 + 5)
Modulators. Side-band generation.

  • Booklet: TBC
  • Slides: PDFPPT

*to update*––> Dec. 7 (Thursday): individual presentations (rehearsal)
*to update*––> Dec. 17 (Sunday): deadline to submit final individual reports


Extra topics

Modulation formats. Coherent communications.
Q-switching.
SESAMs: Semiconductor saturable absorber mirror.

Photodetectors.
Solar cells to ultrafast coherent receivers.
Mid-infrared detectors to solar-blind UV sensors.
Brillouin effect and distributed optical sensing. 
Raman spectroscopy.

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

A design study, summarized in a 5-page report.

  • November 8, 2023 (Wednesday): deadline to submit your abstract (100 words)
  • November 30, 2023 (Thursday): deadline to submit your intermediate report (5 pages)
  • December 7, 2023 (Thursday): individual presentations (rehearsal)
  • December 17, 2023 (Sunday): deadline to submit your final report (5 pages)

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

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.
At the exam, there will be a co-examiner internal to AU.

Grading

The 7-point grading scale is used for the assessment.

  • The highest grade is 12, and corresponds to:
    "an excellent performance displaying a high level of command of all aspects of the relevant material, with no or only a few minor weaknesses"
  • The minimum grade for passing the exam is 2, and corresponds to:
    "a performance meeting only the minimum requirements for acceptance"

How to choose a topic for the design study?

Below are applications notes on recent hot topics in photonics. They are meant to provide a brief entry point for a broad audience.


Other links

Other useful links are provided below.


RP Photonics Encyclopedia
An encyclopedia of optics and optoelectronics, laser technology, optical fibers, nonlinear optics, optical communications, imaging science, optical metrology, spectroscopy and ultrashort pulse physics.


Thorlabs
An American privately held optical equipment company. In addition to their products, Thorlabs' website contains technical resources that include tutorials, application notes, white papers, lab facts, etc.


European Photonics Industry Consortium (EPIC)
A not-for-profit association that serves the photonics community through a regular series of workshops, market studies and partnering.
EPIC also manages the website Jobs in Photonics.


Optica
The largest collection of peer-reviewed optics and photonics content.


Storage

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

Slides and other files are available at this SharePoint site.