Advisors

Particle guidance

Hollow-core photonic crystal fibre (HC-PCF) uniquely allows small objects to be laser-propelled along a low loss waveguide core by radiation pressure. This system allows the measurement of tiny external forces on particles guided both in liquid-filled [1,2] and air-filled HC-PCFs [3]. The forces can be precisely determined either by balancing them against the radiation pressure or by monitoring the velocity of particles via an in-fibre Doppler velocimetry technique [4]. Our measurements recently lead to the discovery of a novel optothermal trapping mechanism that occurs in air-filled hollow-core photonic crystal fibre [5]. We also studied the mechanical response of biological cells [6].  As a PhD student you would get involved in all aspects of this work, including developing new techniques for guiding living cells in liquid-filled HC-PCF and optically propelling charged particles along gas-filled fibres with special built-in microelectrodes.

References

  1. T. G. Euser, M. K. Garbos, J. S. Y. Chen and P. St.J. Russell, Precise balancing of viscous and radiation forces on a particle in liquid-filled photonic bandgap fiber, Opt. Lett. 34, 3674 (2009).
  2. M. K. Garbos, T. G. Euser and P. St.J. Russell, Optofluidic immobility of particles trapped in liquid-filled hollow-core photonic crystal fiber, Opt. Express 19, 19643 (2011).
  3. O. A. Schmidt, M. K. Garbos, T. G. Euser and P. St.J. Russell, Metrology of laser-guided particles in air-filled hollow-core photonic crystal fiber, Opt. Lett. 37, 91 (2011).
  4. M. K. Garbos, T. G. Euser, O. A. Schmidt, S. Unterkofler and P. St.J. Russell, Doppler-velocimetry on micro-particles trapped and propelled by laser light in liquid-filled photonic crystal fiber, Opt. Lett. 36, 2020 (2011).
  5. O. A. Schmidt, M. K. Garbos, T. G. Euser and P. St.J. Russell, Reconfigurable optothermal microparticle trap in air-filled hollow-core photonic crystal fiber, Phys. Rev. Lett. 109, 024502 (2012).
  6. S. Unterkofler, M. K. Garbos, T. G. Euser and P. St.J. Russell, Long-distance laser propulsion and deformation monitoring of cells in optofluidic photonic crystal fiber, J. Biophot. (in press).

Figure: (a) SEM image of HC-PCF structure, core radius is 6 µm. (b) Measured near-field intensity profile at 1064 nm. (c) Schematic of the setup (top) and the optothermal trapping mechanism (bottom). NA – numerical aperture. (d) Movie image sequence of a particle with a radius of 3 µm propelled along the fibre by 50 mW of laser power. The particle stops abruptly when approaching the black mark (length 0.5 mm). The dashed red line indicates the particle trajectory obtained from numerical calculations (from [5]).

Contact:

Dr. Tijmen Euser (tijmen.euser@mpl.mpg.de)