Olav Gaute Hellesø
Job description
Head of Department of Physics and Technology, member of the research group for Photonics, and professor in that field. I have worked at the department since December 1997, first as associate professor and since 2012 as professor.
Education:
- Cand. scient. University of Bergen, 1989
- DEA, INP de Grenoble, France, 1990
- Dr. de l'INP de Grenoble, France, 1994
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Research interests
The research is focused on optical waveguides for trapping and sensing, and combining optical waveguides with Raman spectroscopy.
Waveguides can be used to trap, propel and detect nano- and microparticles. We have demonstrated that the waveguides can be used to squeeze red blood cells, which can be used to measure their elasticity. The elasticity of red blood cells is very important for their functions in the body and the measured elasticity was related to how long the cells had been stored. Regarding trapping of microparticles, a small gap (2um) in a waveguide loop can tightly trap a microparticle, while a wider gap (10um) can be used to levitate a particle above the surface of the chip. When a microparticle is trapped on a waveguide Mach-Zehnder interferometer, it induces a measureable phase change, which can be related to the size of the trapped particle.
Waveguides can be used to make highly sensitive interferometers. In order to detect methane, we cover the waveguide (sensing arm) by a polymer (SAN) doped with a cage-shaped molecule (cryptophane-A). Methane diffuses into the polymer and is trapped in the cage-molecule. This gives a change in the refractive index of the polymer, which gives a phase-change for the evanescent field of the guided mode. This is detected by the interferometer and can be related to the concentration of methane. We have used this method to measure the methane concentration down to 6 ppm.
Teaching
Have been teaching FYS-1003 Experimental physics, FYS-2008 Measurement techniques and FYS-3009 Photonics. Not currently teaching because of duties as head of department.