PhD scholarship in Optical Frequency Comb Generation using Machine Learning

Applications are invited for a 3-year PhD position funded by the Silicon Photonics for Optical Communications (SPOC) centre of excellence at DTU Fotonik. The centre was established in 2015 and is funded by the Danish National Research Foundation. The goal of the SPOC centre is to advance the state-of-the-art in ultra-high capacity optical communications and this PhD project will be at the heart of this activity.   

The objective of the proposed PhD project is to investigate how machine learning methods can be used for optical frequency comb generation and control. More specifically, the project will investigate inverse system design for low-noise frequency comb generation. The start date is flexible, but preferably before May 1, 2021. The project is interdisciplinary and will cover topics within the field of laser physics, machine learning, device physics and optical communication. The project will be carried out in Machine Learning in Photonic Systems (M-LiPS) group. The group has a strong track record and industry collaboration in the application of machine learning techniques to optical communication and measurements systems in general. A close collaboration with the University of California Santa Barbara (Prof. John E. Bowers group) is envisioned within the project.   

This Ph.D. project will develop a machine learning framework for optical frequency combs generation. More specifically, we will investigate how machine learning enabled inverse system learning can be used to generate low-noise spectrally broad frequency combs based on micro-resonator rings or other technologies. Moreover, the project will investigate how machine learning can be explored to enable arbitrary-shape spectrum generation in a controlled way – a feature important for the next generation of AI enabled optical networks. The developed combs will then be investigated for optical data signal transmission as well as RF and THz signal generation.

Responsibilities and qualifications
Your work will include research into machine learning methods for inverse system design applied to optical frequency comb generation. Specifically you will focus on the following areas:

• Physics based numerical models for optical frequency comb generation
• Multi-layer neural networks for inverse system design
• Optimization methods
• Novel training algorithms for multi-layer neural networks
• Experimental verification of the designs
• Optical transmission experiments
• Maintenance  of the GitHub repository for the developed code
• Organising and managing joint experiments with the collaboration groups

You must have a two-year master's degree (120 ECTS points) or a similar degree with an academic level equivalent to a two-year master's degree.

You are expected to have experience with laser physics, machine learning, device physics and optical communication systems. Moreover you shall have additional skills as:

• Good understanding of laser and device physics
• Good understanding of digital signal processing (signal analysis, power spectrum estimation, time-series analysis)
• Good theoretical understanding of linear algebra
• Good understanding of numerical methods for optimization
• Experience with machine learning techniques (expectation maximization algorithms, neural networks, Guassian processes, etc.)
• Experience using MATLAB, Python or similar
• Experience with software for version control such as git
• Ability to work independently, to plan and carry out complicated tasks
• Good communication skills in English, both written and spoken
• Innovative skills and the ability to generate new ideas

Approval and Enrolment
The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see DTU's rules for the PhD education.

Assessment
The assessment of the applicants will be made by Professor Darko Zibar and Professor Leif K. Oxenløwe.

We offer
DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

Salary and appointment terms
The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is 3 years.

Will be at DTU Fotonik at the Kgs. Lyngby Campus. 

You can read more about career paths at DTU here. 

Further information
Further information may be obtained from Professor Darko Zibar (dazi@fotonik.dtu.dk). The following papers is a good indication of the nature of the project:

1. D. Zibar, A. M. Rosa Brusin, U. C de Moura, V. Curri, Andrea Carena, “Inverse system design using machine learning: the Raman amplifier case,” Journal of Lightwave Technology, vol. 38, no. 4, pp: 736-753, 2020

You can read more about DTU Fotonik at www.fotonik.dtu.dk/english.

If you are applying from abroad, you may find useful information on working in Denmark and at DTU at DTU – Moving to Denmark.

Application procedure
Your complete online application must be submitted no later than 1 February 2022 (Danish time). Applications must be submitted as one PDF file containing all materials to be given consideration. To apply, please open the link "Apply online", fill out the online application form, and attach all your materials in English in one PDF file. The file must include:

• A letter motivating the application (cover letter)
• Curriculum vitae
• Grade transcripts and BSc/MSc diploma including official description of grading scale

You may apply prior to ob­tai­ning your master's degree but cannot begin before having received it.

Applications received after the deadline will not be considered.

All interested candidates irrespective of age, gender, race, disability, religion or ethnic background are encouraged to apply.

DTU Fotonik has 220 employees with competences in optics. In a typical year, DTU Fotonik educates 55 PhD students from more than 25 countries and our student numbers are constantly growing. As one of Europe’s largest public photonics research departments, DTU Fotonik covers a multitude of optical disciplines ranging from fundamental light-matter interaction and optical telecommunications to applied research and innovation. Our research topics include optical sensors, lasers, LEDs, photovoltaics, ultra-high speed optical transmission systems, bio-photonics, nano-optics and quantum photonics.

Technology for people
DTU develops technology for people. With our international elite research and study programmes, we are helping to create a better world and to solve the global challenges formulated in the UN’s 17 Sustainable Development Goals. Hans Christian Ørsted founded DTU in 1829 with a clear vision to develop and create value using science and engineering to benefit society. That vision lives on today. DTU has 12,900 students and 6,000 employees. We work in an international atmosphere and have an inclusive, evolving, and informal working environment. DTU has campuses in all parts of Denmark and in Greenland, and we collaborate with the best universities around the world.