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Photonic Integrated Circuits (PICs)

renamed from "Photonic Devices"

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

Purpose, etc.

Course content

This course offers a comprehensive dive into cutting-edge photonic technologies, covering:

  • Light-matter interaction: Basics of light generation and emission.
  • PN junctions: Recap of modes and PN junction principles.
  • Material platforms: Confinement of light and materials used in photonics.
  • Recombination processes: Growth, lattice matching, and recombination mechanisms.
  • Optical amplification: Erbium-doped fiber amplifiers and wavelength division multiplexing.
  • Laser performance: Conditions for lasing and rate equations.
  • Dynamics: Modulation and wavelength chirp.
  • Reflectors: Thin films, Bragg reflectors, and optical feedback mechanisms.

The course combines lectures, exercises, and lab demos, culminating in a design study for the final evaluation.

Purpose of the course

This course aims to provide students with a deep understanding of the fundamental principles and practical applications of photonic devices. It covers topics such as light-matter interaction, laser technology, semiconductor optical amplifiers, and more. Students will engage in design studies, hands-on exercises, and lab demonstrations, enhancing practical skills and theoretical knowledge. This course is ideal for those looking to innovate in telecommunications, sensing, and other high-tech industries.

Learning outcome

By the end of this course, participants will:

  1. Explain the physics behind the selected photonic devices;
  2. Model a selected device and/or circuit in a design study;
  3. Explain how a photonic integrated circuit can be made and in which materials;
  4. Know which building blocks are available in each platform and know typical operating parameters;
  5. Discuss the trade-offs that have to be made when choosing a platform and designing a circuit.

ECTS credits: 10

Course coordinator: Nick Volet

Program requirement: Active participation is mandatory.

Prerequisites: Prior knowledge of electromagnetism and optics.

Course assessmentEvaluation will be based on an oral exam and a written report, centered on a design study you will develop, incorporating one or more photonic devices. Grading will follow the seven-point scale and will include an internal co-examiner.

Where and when?

  • At AU-ECE, Building 5125 ("Edison", Finlandsgade 22)
    Lectures: 
    – Mondays 10:15–12:00, in Room 417
    – Thursdays 14:15–16:00, in Room 120
    Exercises + lab demos: 
    – Wednesdays 10:15–12:00, in Room 120

Part 1

1. Light-matter interaction

Aug. 25 + Aug. 27 + Aug. 28 (week 35)
Course introduction and overview.
Introduction to EMode Photonix.
Bandgap and semiconductor properties. 
Absorption, dispersion and scattering.
Spontaneous emission.

  • Slides-APDF – PPT
  • Slides-BPDF – PPT
  • Slides-CPDF – PPT
  • Exercises: PDF
  • Solutions: TBC

→ Start survey: We’re excited to begin this semester with you! To help us better tailor the course to your needs and interests, we’d love to hear your expectations and any suggestions you may have. Your feedback is valuable, and the survey is completely anonymous. Please share your thoughts by clicking this link.


2. On-chip light sources

Sept. 1 + Sept. 3 + Sept. 4 (week 36)
Waveguides, laser principles, and optical modes.
PN junctions, holes, and electron-hole recombination.
Diodes, diode lasers, and their design considerations.
Laser threshold, spectral width, and side-mode suppression.

  • Slides: PDF – PPT
  • Exercises: PDF
    • Design study preparation: PDF

3. Miniaturization and scalability

Sept. 8 + 10 + 11 (week 37)
PN junction fundamentals and bandgap properties. Current and light confinement. 
Double heterostructures, quantum wells, and photonic crystals. 


4. Material platforms

Sept. 15 + 17 + 18 (week 38)
Silicon, indium phosphide, AlGaAs, InGaAsP, etc.
Wafer fabrication, lattice matching, bandgap engineering.
Distributed Bragg reflectors (DBRs), phase shifts.
Process Design Kit (PDK), Multi-Project Wafer (MPW), photonic integration.

Sept. 18 (Thursday): Deadline to submit group abstracts

  • Slides: PDFPPT
  • Exercises: Group work for projects

5. Blue lasers

Sept. 22 + 24 + 25 (week 39)
Blue laser diodes, GaN substrates, quantum wells, nonlinear optics.
Blu-ray technology, industrial applications, metal cutting.

→ Sept. 22 (Monday): Feedback on submitted abstracts: PDFPPT


6. Visible photonics and semiconductor growth

Sept. 29 + Oct. 1 + 2 (week 40)
Visible photonics: laser diode technology, green gap challenge, nonlinear optics, second-harmonic generation (SHG), speckle patterns, superluminescent diodes (SLEDs), optical parametric oscillators (OPOs).
Epitaxial growth: Molecular Beam Epitaxy (MBE) vs Metal-Organic Vapor Phase Epitaxy (MOVPE), lattice matching, dislocations, quantum dots, wafer bonding, and heterogeneous photonic integration.

  • Slides-A: PDFPPT
  • Slides-B: PDFPPT
  • Exercises: TBC
  • Solutions: TBC

7. Recombination processes

Oct. 6 + 8 + 9 (week 41)
Dangling bonds and surface passivation. Band structure and direct/indirect bandgaps. Radiative and non-radiative recombination (Auger process). Phonons and momentum conservation. 

→ Oct. 6 (Monday): Deadline to submit group reports
→ Oct. 9 (Thursday): Group presentations

Week 42 (Oct. 13 – 17): no teaching at AU.

Curious about 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. Optical amplification

Oct. 20 + 22 + 23 (week 43)
Infrared C-band: scattering, attenuation, and zero-dispersion point.
Erbium-doped fiber amplifiers (EDFAs). Wavelength division multiplexing (WDM), coarse and dense WDM, and future integrated amplifiers.
Transverse confinement factor. Net gain and saturation.
Semiconductor optical amplifiers (SOAs). Small-signal gain factor.

  • Solutions: PDF

Oct. 23 (Wednesday): R-Day starting at 12:30 at the Peter Bøgh Auditorium in Building 5335, followed by a poster session 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.


9. Laser performance

Oct. 27 + 29 + 30 (week 44)
Confinement factors (transverse and longitudinal), comparison between edge-emitting lasers and VCSELs.
Lasing threshold conditions, gain clamping, rate equations for carrier and photon densities, power-current characteristics, free spectral range (FSR), and practical design considerations for optimizing laser performance.

  • Solutions: PDF

🎤 Oct. 28, 2024 (Monday) at 15:15:
Guest lecture by Eric Stanton, Co-Founder of EMode Photonix.
Video: MPG ; Summary: PDF.


10. Dynamics

Nov. 3 + 5 + 6 (week 45)

Nov. 5 (Wednesday): Deadline to submit individual abstracts

Turn-on delay. Small-signal modulation. Wavelength chirp.
Deep-UV photonics: Lasers, fibers and detectors. Nonlinear crystals and lithography.

🍕 Nov. 7 (Thursday) at 12:00:
Pizzas and guest lecture by Peter Tønning, Senior System Engineer at UV Medico.
Summary: PDF


11. Narrow-linewidth lasers and ring resonators

Nov. 10 + 12 + 13 (week 46)

→ Nov. 10 (Monday): Feedback on submitted abstracts: PDFPPT, see all

Narrow linewidth lasers:
Intrinsic linewidth and coherence length. 
Fiber lasers.
Optical feedback.
External-cavity diode lasers (ECDLs).

Ring resonators:
Transmission spectrum. Critical coupling.
Quality factor. Effective phase shift.
Applications: filters, mirrors, isolators, optical frequency combs, and all-optical switches.

November 2024: Guest lecture from Asger Sellerup Jensen, Senior Market Development Manager & Head of Quantum at NKT Photonics
Video: MPG


12. Reflectors

Nov. 17 + 19 + 20 (week 47)

Thin films and anti-reflective (AR) coatings. Distributed Bragg reflectors (DBRs). Corrugated waveguides. Fiber Bragg gratings (FBGs). Fabry-Perot interferometer and etalons.

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

13. Mid-infrared, modulations, and combs

Nov. 24 + 26 + 27 (week 48)
Mid-infrared lasers and applications: quantum cascade lasers (QCLs), difference-frequency generation (DFG), and their roles in sensing, free-space communication, and quantum technologies.
HiTran database.

Photodetection
Photodetectors.
Solar cells to ultrafast coherent receivers.
Mid-infrared detectors to solar-blind UV sensors.


14. Review

Dec. 1 + 3 + 4 (week 49)
Incoherence
Speckle effect. Superluminescent diodes (SLEDs) and their applications.
Optical coherence tomography (OCT): principles and uses.
Sagnac effect and modern optical gyroscopes.

Dec. 4 (Thursday): Individual presentations (rehearsal)
Dec. 11 (Thursday): Deadline to submit final individual reports


Extra topics

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

Pulses
Modulators. Side-band generation.
Modulation formats. Coherent communications.
Q-switching.
SESAMs: Semiconductor saturable absorber mirror.
Spiking and neuron networks

Steering
Scanners, optical phased arrays (OPAs).
Light detection and ranging (LIDAR).

Scattering
Brillouin effect and distributed optical sensing. 
Raman spectroscopy.

Simulation exercises

We use EMode Photonix to simulate waveguide modes. It offers a practical and powerful way to model and analyze waveguide behavior.

👉 Click here for instructions and resources to get started with EMode Photonix.


Exam: January 9, 2026

Evaluation will be based on an oral exam and a written report, centered on a design study you will develop, incorporating photonic integrated circuits.

  • November 5 (Wednesday, week 45): Deadline to submit your abstract

  • December 4 (Thursday, week 49): Individual presentations (rehearsal)

  • December 11 (Thursday, week 50): Deadline to submit your final report

For those that would like to attend the exam, please send your abstract and report to Nick 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.



Storage

Slides and other files are available at this SharePoint site.

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