PhD in 'Photonics - Listening to groundwater with distributed fiber optic sensing'

1 - Working at the VUB

For more than 50 years, the Vrije Universiteit Brussel has stood for freedom, equality and solidarity, and this is very much alive on our campuses among students and staff alike. 

At the VUB, you will find a diverse collection of personalities: innovators pur sang, but above all people who are 100% their authentic selves. With some 4,000 employees, we are the largest Dutch-speaking employer, in the private sector, in Brussels; an international city with which we are only too happy to connect and where (around) our 4 campuses are located. 

Add to this our principle of free research - in which self-reflection, a critical attitude and an open, creative mind around scientific and social issues are central - and you have a university that is fundamentally groundbreaking and pioneering in education and research. In short: the VUB all over again. 

Moreover, the VUB is a member of EUTOPIA, an alliance of like-minded European universities, all ready to reinvent themselves.

2 - Position description

The Faculty of Engineering, Department Applied Physics and Photonics, Research Group Brussels Photonics is looking for a PhD-student with a doctoral grant. 

More concretely your work package, for the preparation of a doctorate, contains: 

Hydrogeologists use numerical groundwater flow models for predicting impacts of climate change and pumping on groundwater and understanding and quantifying groundwater drought resilience and adaptation. Current groundwater flow models, however, often exhibit important uncertainties related to input parameters and boundary conditions. Reducing this uncertainty is difficult if these models are only calibrated using groundwater level measurements. We know that measurements of groundwater fluxes are very sensitive to model parameters and boundary conditions and could reduce model uncertainty significantly. Unfortunately, it is challenging to measure groundwater fluxes in the field. A new sensor prototype developed by the company iFLux to measure real-time groundwater fluxes in the field is promising, but delivers very local measurement only. Therefore, it would be interesting to combine these local measurements with distributed measurements of fluxes that can reveal variations in space.

This PhD-research aims to investigate the potential of (quasi-)distributed optical fibre sensing techniques for measuring groundwater fluxes through sensor development, lab and field experiments, modelling and uncertainty assessment with a focus on two case studies: a shallow unconsolidated aquifer and fractured rock to assess to what extent and in which conditions (quasi-)distributed fibre-optic sensing can be used to estimate groundwater fluxes and result in uncertainty reduction in numerical groundwater flow models. It fits in a research grant that our team has won for the project named "Can we Listen to Groundwater?", fully funded by the Research Foundation Flanders (Fonds Wetenschappelijk Onderzoek, FWO). 

In this context, we are looking for an excellent PhD candidate in photonics (maximum duration = 48 months) to join our team. The research work will include: 

• Development of fibre-optic quasi-distributed sensors based on both distributed acoustic sensing (DAS) and fibre Bragg grating (FBG) sensors.
• Benchmarking experiments in sandbox and in fractured rock surrogate
• Deriving relations between the detected fiber-optic sensor signals and groundwater flux
• Field testing of the developed sensors

The candidate will join the Brussels Photonics (B-PHOT) research group, part of the Department of Applied Physics and Photonics. B-PHOT is a multidisciplinary team of around 70 people, including full-time researchers, technical experts, and administrative support. The group values diversity, inclusion, and gender balance, and offers a stimulating research environment at the forefront of photonics innovation. More information can be found on our website: https://www.b-phot.org. The candidate will be supervised by Prof. Francis Berghmans, and co-supervised by Dr. Sidney Goossens and Dr. Sergei Mikhailov. Given that the PhD project is embedded in an interdisciplinary collaboration between B-PHOT and the Department of Water and Climate (HYDR), the candidate will work in close collaboration with HYDR and with another PhD researcher affiliated with this department, ensuring synergy between photonics-based sensing and hydro-environmental applications.

Whilst the main office will be located at the Brussels Humanities, Sciences & Engineering Campus (Etterbeek), regular work at our Photonics Innovation Center in Pajottegem will be required, in function of experimental work, collaboration, or meetings.

For this function, our Brussels Humanities, Sciences & Engineering Campus (Elsene) will serve as your home base. 

3 - Profile

What do we expect from you?

• Candidates should possess a master’s degree in Electrical Engineering, Physics, Photonics, Applied Math or related scientific field.

  Candidates that have not yet acquired their master’s degree can apply and participate in the selection procedure, but need to offer proof of registration in their Masters programme and need to have complied with all diploma requirements before starting their position at VUB.

• The candidate must demonstrate a strong and sustained interest in photonic systems and light-based technologies aimed at advancing climate action, environmental protection, and sustainability.

  Demonstrable knowledge of photonics, fibre-optics, sensing and signal processing is required.

  Good programming skills are a strong plus. Experience with Matlab, Python or a similar language and environment is a plus, supplemented with good knowledge of numerical techniques and advanced simulation methods.

  Experience with experimental optical setup and equipment such as optical fiber sensors, fiber interrogators, optical spectrum analysers, laser drivers or amplifiers is a plus. 

  The candidate is expected to be able to carry out the research activities independently and in a critical manner, whilst having excellent communication skills and a positive attitude towards collaboration. 

  Good time management skills are a must, along with the ability to meet tight deadlines and work efficiently under pressure and in a collaborative setting.

  Proficiency in both spoken and written English (typically CEFR level C1 or equivalent) is required. The candidate will have the opportunity to take evening English classes to improve his/her language skills if needed.

  The candidates should be prepared to travel in Europe and potentially worldwide e.g. for participation in conferences or research stays at partner institutions.

• You have not performed any works in the execution of a mandate as an assistant, paid from operating resources, over a total (cumulated) period of more than 12 months.

• As a (non-)EEA national, meet the conditions for obtaining a valid permit for VUB and comply with the VUB residence requirements. More info here.

The VUB wants to be a reflection of the society where everyone's talent is valued, regardless of gender, age, religion, skin color, migration background, disability and neurodiversity.

4 - Offer

Are you going to be our new colleague?

You’ll be offered a full-time PhD-scholarship, for 12 months (extendable up to max. 48 months, on condition of the positive evaluation of the PhD activities), with planned starting date 01/04/2026. 

You’ll receive a grant linked to one of the scales set by the government.

IMPORTANT: The effective result of the doctorate scholarship is subject to the condition precedent of your enrolment as a doctorate student at the university.

At the VUB, you’re guaranteed an open, involved and diverse workplace where you are offered opportunities to (further) build on your career.

As well as this, you will also enjoy various other benefits:

• Extensive homeworking options, a telework allowance of 50 euros per month OR an internet fee of 20 euros per month;
• An open and informal working environment where attention is paid to work-life balance, and exceptional holiday arrangements with 35 days of leave (based on a fulltime contract), closure between Christmas and New Year and 3 extra leave days;
• Cost-free hospitalisation insurance;
• Full reimbursement of your home-to-work commute with public transport according to VUB-policy, and/or compensation if you come by bike; 
• A wide selection of meals in our campus restaurants at attractive prices;
• Excellent and affordable facilities for sport and exercise, a range of discounts via Benefits@Work (in  all kinds of shops, on flights, in petrol stations, amusement parks...) and Ecocheques; 
• Nursery near campus, discount on holiday camps; 
• The space to form your job content and to continuously learn through our VUB learning platforms and training courses;
• And finally: great colleagues with a healthy drive.

5 - Interested?

Is this the job you’ve been dreaming of?

Then apply, at the latest on 22/02/2026, via jobs.vub.be, and upload the following documents:

• your CV;
• your motivation letter;
• your diploma (not applicable for VUB alumni).

Our application process is as follows (subject to change):

• step 1: an initial selection based on your application file; 
• step 2: a job interview.

Do you have questions about the job content? Contact Sidney Goossens at sidney.goossens@vub.be or on Not applicable.

Would you like to know what it’s like to work at the VUB? Go to jobs.vub.be, and find all there is to know about our campuses, benefits, strategic goals and your future colleagues.

Would you like more information about EUTOPIA? Go to eutopia-university.eu, and read more about the role of the VUB in the development of the EUTOPIA alliance.