Current research / employment Hollow-core photonic crystal fibres (PCFs) provide the unique capability to study the interaction of light and matter on length scales of extreme aspect ratios. Due to the photonic crystal cladding, the light is confined in the hollow core enabling to fill the fiber core with matter such as gases. Furthermore, the radiation pressure of light, i.e. the photon momentum, allows trapping microparticles (optical tweezer) and pushing them into the PCF. For instance, glass spheres can act as probe for physical properties of gaseous substances or, accelerating them in vacuum, the airborne microparticles can function as laser-driven rockets for medical applications. The upper left sketch in the figure below depicts a dual beam trap consisting of two counter propagating laser beams, each focused by a lens. In between the two focal points the particle is stably trapped by the laser light. To launch microspheres into a hollow-core PCF, the holey fibre replaces one of the lenses (lower scheme). In experiment, a glass sphere was trapped in front of the bright PCF end facet. Decreasing the power of the fibre beam, the light pressure propels the particle along the hollow core. Future prospects include sensing applications as well as particle acceleration and transport.
Publications O. A. Schmidt, M. K. Garbos, T. G. Euser, P. St.J. Russell, Metrology of laser-guided particles in air-filled hollow-core photonic crystal fiber, Opt. Lett., 37, 91-93, (2012)

O. A. Schmidt, M. K. Garbos, T. G. Euser, P. St.J. Russell, Reconfigurable optothermal microparticle trap in air-filled hollow-core photonic crystal fiber, Phys. Rev. Lett., 109, 024502, (2012)

M. K. Garbos, T. G. Euser, O. A. Schmidt, S. Unterkofler, P. St.J. Russell, Doppler velocimetry on microparticles trapped and propelled by laser light in liquid-filled photonic crystal fiber, Optics Letters, 36(11), 2020-2022, (2011)