TY - GEN
T1 - Fiber optic trapping of low-refractive-index particles
AU - Mohanty, Khyati Samarendra
AU - Liberale, Carlo
AU - Mohanty, Samarendra Kumar
AU - Degiorgio, Vittorio
AU - Cabrini, Stefano
AU - Carpentiero, Alessandro
AU - Garbin, Valeria
AU - Prasciolu, Mauro
AU - Cojoc, Dan
AU - Di Fabrizio, Enzo
PY - 2006
Y1 - 2006
N2 - Since the low index particles are repelled away from the highest intensity point, trapping them optically requires either a rotating Gaussian beam or optical vortex beams focused by a high numerical microscope objective. However, the short working distance of these microscope objectives puts a limit on the depth at which these particles can be manipulated. Here, we show that axicon like structure built on tip of a single mode optical fiber produces a focused beam that is able to trap low index particles. In fact, in addition to transverse trapping inside the dark conical region surrounded by high intensity ring, axial trapping is possible by the balance of scattering force against the buoyancy of the particles. The low-index particle system consisted of an emulsion of water droplets in acetophenone. When the fiber was kept horizontal, the low index spheres moved away along the beam and thus could be transported by influence of the scattering force. However in the vertical position (or at an angle) of the fiber, the particles could be trapped stably both in transverse and axial directions. Chain of such particles could also be trapped and transported together by translation of the fiber. Using escape force technique, transverse trapping force and thus efficiency for particle in Mie regime was measured. Details of these measurements and theory showed that trapping of Raleigh particle is possible with such axicon-tip fibers. This ability to manipulate low-index spheres inside complex condensed environments using such traps will throw new insights in the understanding of bubble-bubble and bubble-wall interactions, thus probing the physics behind sonoluminescence and exploring new applications in biology and medicine.
AB - Since the low index particles are repelled away from the highest intensity point, trapping them optically requires either a rotating Gaussian beam or optical vortex beams focused by a high numerical microscope objective. However, the short working distance of these microscope objectives puts a limit on the depth at which these particles can be manipulated. Here, we show that axicon like structure built on tip of a single mode optical fiber produces a focused beam that is able to trap low index particles. In fact, in addition to transverse trapping inside the dark conical region surrounded by high intensity ring, axial trapping is possible by the balance of scattering force against the buoyancy of the particles. The low-index particle system consisted of an emulsion of water droplets in acetophenone. When the fiber was kept horizontal, the low index spheres moved away along the beam and thus could be transported by influence of the scattering force. However in the vertical position (or at an angle) of the fiber, the particles could be trapped stably both in transverse and axial directions. Chain of such particles could also be trapped and transported together by translation of the fiber. Using escape force technique, transverse trapping force and thus efficiency for particle in Mie regime was measured. Details of these measurements and theory showed that trapping of Raleigh particle is possible with such axicon-tip fibers. This ability to manipulate low-index spheres inside complex condensed environments using such traps will throw new insights in the understanding of bubble-bubble and bubble-wall interactions, thus probing the physics behind sonoluminescence and exploring new applications in biology and medicine.
KW - Laser trapping
KW - Low refractive index particles
KW - Optical fiber
UR - http://www.scopus.com/inward/record.url?scp=33646202317&partnerID=8YFLogxK
U2 - 10.1117/12.647254
DO - 10.1117/12.647254
M3 - Conference contribution
AN - SCOPUS:33646202317
SN - 081946130X
SN - 9780819461308
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
T2 - Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV
Y2 - 23 January 2006 through 25 January 2006
ER -