Francis Berghmans

The Vrije Universiteit Brussel (VUB) invites applications for a fully funded PhD position in photonics, focusing on the innovative use of distributed fiber optic sensing to monitor groundwater fluxes. This research is embedded within the Brussels Photonics (B-PHOT) research group, part of the Department of Applied Physics and Photonics, and is supported by the Research Foundation Flanders (FWO) through the project "Can we Listen to Groundwater?". The project aims to address uncertainties in numerical groundwater flow models by developing and deploying (quasi-)distributed optical fiber sensors, including distributed acoustic sensing (DAS) and fiber Bragg grating (FBG) technologies, to measure groundwater fluxes in both shallow unconsolidated aquifers and fractured rock environments. The successful candidate will join a multidisciplinary team of around 70 researchers, technical experts, and administrative staff, working in close collaboration with the Department of Water and Climate (HYDR). The research will involve sensor development, laboratory and field experiments, modeling, and uncertainty assessment, with the goal of integrating local and distributed measurements to improve environmental monitoring and climate resilience. The candidate will be supervised by Prof. Francis Berghmans, with co-supervision from Dr. Sidney Goossens and Dr. Sergei Mikhailov, ensuring strong interdisciplinary support and synergy between photonics and hydro-environmental applications. Applicants should hold a master’s degree in Electrical Engineering, Physics, Photonics, Applied Mathematics, or a related field. Candidates with demonstrable knowledge of photonics, fiber-optics, sensing, and signal processing are preferred, and programming skills (Matlab, Python, or similar) as well as experience with optical sensor equipment are advantageous. Proficiency in English (CEFR C1 or equivalent) is required, and candidates should be prepared to travel for conferences or research stays. The position offers a full-time PhD scholarship for 12 months, extendable up to 48 months based on performance, with a grant linked to government scales and a comprehensive benefits package including telework allowance, hospitalisation insurance, public transport reimbursement, campus meal discounts, sports facilities, nursery discounts, and access to training courses. The main office will be at the Brussels Humanities, Sciences & Engineering Campus (Etterbeek), with regular work at the Photonics Innovation Center in Pajottegem. VUB is committed to diversity, inclusion, and gender balance, providing a stimulating and supportive research environment. The application deadline is 22 February 2026. Interested candidates should apply online via jobs.vub.be, submitting a CV, motivation letter, and diploma (not required for VUB alumni). The selection process includes an initial review and a job interview. For further information about the research group, visit B-PHOT , and for questions about the position, contact Dr. Sidney Goossens at [email protected] . This PhD opportunity is ideal for candidates passionate about photonics, environmental science, and interdisciplinary research, offering the chance to contribute to cutting-edge sensor development and climate action at a leading European university.

Vrije Universiteit Brussel (VUB) is offering a PhD position within the Faculty of Engineering, Department of Applied Physics and Photonics, in the Brussels Photonics research group (B-PHOT). The project is part of RheoLub , a Research Foundation - Flanders (FWO)-funded collaboration aimed at developing advanced experimental and modelling methods to understand industrial lubricants under extreme operating conditions. The PhD research focuses on optical fibre sensing for ultra-high-pressure rheometry. The central goal is to design, develop, calibrate, and validate miniature fibre-optic sensors capable of measuring pressure and temperature inside a new generation of ultra-high-pressure rheometers. The work targets a slit-die rheometer cartridge in which optical fibres are integrated close to the lubricant flow channel to enable spatially resolved pressure and temperature profiling under very high pressures, high temperatures, and high shear rates. The research program includes numerical design of sensor integration strategies, development of arrays of Fiber Bragg Grating (FBG) sensors in standard single-mode and/or microstructured fibres, investigation of pressure-sensitive fibre concepts such as the Butterfly microstructured optical fibre developed at VUB, and sensing approaches based on birefringence. The project also involves high-pressure calibration experiments, analysis of pressure-temperature cross-sensitivity, spectral data processing, temperature compensation, and conversion of measured strain into pressure. Sensor integration and validation will be done in close collaboration with Ghent University, which is developing the rheometer cartridge, thin-film reference sensors, and digital-twin-based methods for extracting material properties. The successful candidate will join an internationally oriented photonics group and will be supervised by Prof. Francis Berghmans and Dr Sidney Goossens. The position may include limited teaching-related duties such as supervising practical sessions or master’s thesis students, but these tasks will remain minor and aligned with the research schedule. Applicants should hold a Master’s degree in engineering, physics, photonics, applied physics, electrical engineering, mechanical engineering, materials science, or a related field. Candidates who have not yet completed the degree may still apply if they can provide proof of enrolment and satisfy all degree requirements before starting. Required skills include a strong interest in photonic sensing, optical fibre technology, and experimental research; knowledge of photonics, fibre optics, FBGs, optical sensing, signal processing, and/or experimental optics; and good English communication skills. Experience with MATLAB, Python, LabVIEW, COMSOL Multiphysics, finite-element modelling, optomechanical simulations, sensor integration, bonding, coatings, high-pressure testing, and instrumentation is considered beneficial. The appointment is offered as a full-time PhD scholarship for 12 months, extendable up to 48 months based on positive evaluation, with a planned start date of 01/01/2027. The scholarship includes a grant linked to government scales. The main workplace is the Brussels Humanities, Sciences & Engineering Campus in Etterbeek, with regular activity also possible at the Photonics Innovation Center in Pajottegem. Applications must be submitted through jobs.vub.be by 30 September 2026. Candidates should upload a CV, motivation letter, and diploma if applicable. Questions about the job content can be directed to Sidney Goossens at [email protected].