Highly Efficient Dual-Fiber Optical Trapping with 3D Printed Diffractive Fresnel Lenses

Asa Asadollahbaik (1) , Simon Thiele (1) , Ksenia Weber (1) , Aashutosh Kumar (2) , Johannes Drozella (1) , Florian Sterl (1) , Alois Herkommer (1) , Harald Giessen (3) , Jochen Fick (2)

1 University of Stuttgart
2 NEEL - NOF - Nano-Optique et Forces
3 Universität Stuttgart [Stuttgart]

Highly efficient counter-propagating fiber-based optical traps are presented which utilize converging beams from fibers with 3D printed diffractive Fresnel lenses on their facet. The use of a converging beam instead of diverging beam in dual-fiber traps creates a strong trapping efficiency in both the axial and the transverse directions. Converging beams with a numerical aperture of up to 0.7 are produced by diffractive Fresnel lenses. These lenses also provide a large focal distance of up to 200 μm in a moderately high refractive index medium. Fabrication of such diffractive lenses with microsized features at the tip of a fiber is possible by femtosecond two photon lithography. In comparison to chemically etched fiber tips, the normalized trap stiffness of dual-fiber tweezers is increased by a substantial factor of 35−50 when using a converging beam produced by diffractive Fresnel lenses. The large focal length provided by these diffractive structures allows working at a large fiber-to-fiber distance, which leads to larger space and the freedom to combine other spectroscopy and analytical methods in combination with trapping.

Mots clés: optical trapping; converging counter-propagating beams; two photon polymerization; microstructured fiber; diffractive optical elements; diffractive Fresnel lenses

Domaines: Optique [physics.optics]

Asa Asadollahbaik, Simon Thiele, Ksenia Weber, Aashutosh Kumar, Johannes Drozella, et al.. Highly Efficient Dual-Fiber Optical Trapping with 3D Printed Diffractive Fresnel Lenses. ACS photonics, 2019, 7 (1), pp.88-97. ⟨10.1021/acsphotonics.9b01024⟩. ⟨hal-02464701⟩