Internship | High Sensitive Gas Sensor in Hollow-Core Photonic Bandgap Fiber

Detection of trace gases/chemicals is important for industrial and healthy living applications serving multiple purposes such as, analysis, diagnostic, safety, process monitoring etc.



Education type

university (wo)


Internship and graduation project

Hours a week

Fulltime – 40


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What will you be doing?

Among various sensing technology, optical fiber sensors have advantages such as resistance to harsh environment, immunity to electromagnetic interference and capability for remote detection. High sensitive and high selective gas sensor can be realized through photothermal interferometry spectroscopy building in hollow-core photonic bandgap fiber.

Early gas sensor built in fiber is based on laser absorption spectroscopy (LAS) using micro-optic open-path cells. Due to the limitation of the weak absorption of gases and the difficulty in building long path-length absorption cells in compact size, the sensitivity of the sensor is limited. In recent years, innovation in photonic bandgap fibers has tremendously extended the sensing limit [1]. 
Photothermal interferometry (PTI) is an ultra-sensitive spectroscopic technique for gas chemical compounds analysis. This technique measures the absorption induced photothermal phase modulation via optical interferometry. A hollow-core photonic bandgap fiber (HC-PBF) confines light and gas sample simultaneously in the hollow-core. This 100% overlapping ensures both efficient absorption and robust sensing environment, resulting in a much compact system design.

In this project, we will study the photothermal spectroscopy HC-PBF gas sensor theoretically and experimentally. The propagation mode in HC-PBF is determined by the wavelength, refractive index of the gas and geometry of the hollow core [2]. The mode changes due to varying parameters will be studied through modelling and simulations. The optical interferometer for measurement of the phase changes is critical for the sensor design. In this project, we will evaluate the interferometry experiment measurement of the HC-PBF to determine the sensitivity of the system. 

[1] DOI 10.1515/nanoph-2013-0042
[2] DOI: 10.1109/JLT.2005.859406

In a short introductory period, you will learn the basic principles of photothermal interferometry gas sensing technique. Through the project you will: 
•Perform a literature review on the PTI and HC-PBF system; 
•Develop a numerical model to study propagation mode in HC-PBF; 
•Simulation of gas sensing in HC-PBF;
•Analyze interferometer measurement data to determine the phase change in optical fiber; 
•If the regulations regarding corona later allow, experiment with optical interferometry; 
•Work in an multidisciplinary team; 
•Report on research findings. 

What do we require of you?

  • Master level study on physics; 
  • Knowledge on optics preferably; 
  • Experience in computation tools and languages such as, Matlab / Python

What can you expect of your work situation?

TNO is an independent research organisation whose expertise and research make an important contribution to the competitiveness of companies and organisations, to the economy and to the quality of society as a whole. Innovation with purpose is what TNO stands for. With 3000 people we develop knowledge not for its own sake but for practical application. To create new products that make life more pleasant and valuable and help companies innovate. To find creative answers to the questions posed by society. We work for a variety of customers: governments, companies, service providers and non-governmental organisations. Working together on new knowledge, better products and clear recommendations for policy and processes. In everything we do, impact is the key. Our product and process innovations and recommendations are only worth something if our customers can use them to boost their competitiveness. 

The work will be carried out in Optics group, location Delft. If you would like to know more about the activities in our group please click here

What can TNO offer you?

You want to work on the precursor of your career; an internship gives you an opportunity to take a good look at your prospective future employer. TNO goes a step further. It’s not just looking that interests us; you and your knowledge are essential to our innovation. That’s why we attach a great deal of value to your personal and professional development. You will, of course, be properly supervised during your internship and be given the scope for you to get the best out of yourself. Naturally, we provide suitable internship compensation.

Application process

For this vacancy it is required that the AIVD issues a security clearance after conducting a security screening. Please visit for more information the AIVD website.

Has this vacancy sparked your interest?

Then please feel free to apply on this vacancy! For further questions don’t hesitate to contact us.

Due to Covid-19 and the consequent uncertainties and restrictions, students who are not residing in the Netherlands may currently not be able to start an internship or graduation project at TNO.

Contact: Man Xu
Phone number: +31 (0)6-818 99423

Note that applications via email and third party applications are not taken into consideration.


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