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Proceedings Paper

Optical trapping with superfocused high-M2 laser diode beam
Author(s): G. S. Sokolovskii; V. V. Dudelev; Vasileia Melissinaki; S. N. Losev; Ksenya K. Soboleva; A. G. Deryagin; V. I. Kuchinskii; M. Farsari; W. Sibbett; E. U Rafailov
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Paper Abstract

Many applications of high-power laser diodes demand tight focusing. This is often not possible due to the multimode nature of semiconductor laser radiation possessing beam propagation parameter M2 values in double-digits. We propose a method of ‘interference’ superfocusing of high-M2 diode laser beams with a technique developed for the generation of Bessel beams based on the employment of an axicon fabricated on the tip of a 100 μm diameter optical fiber with high-precision direct laser writing. Using axicons with apex angle 1400 and rounded tip area as small as ~10 μm diameter, we demonstrate 2-4 μm diameter focused laser ‘needle’ beams with approximately 20 μm propagation length generated from multimode diode laser with beam propagation parameter M2=18 and emission wavelength of 960 nm. This is a few-fold reduction compared to the minimal focal spot size of ~11 μm that could be achieved if focused by an ‘ideal’ lens of unity numerical aperture. The same technique using a 1600 axicon allowed us to demonstrate few-μm-wide laser ‘needle’ beams with nearly 100 μm propagation length with which to demonstrate optical trapping of 5-6 μm rat blood red cells in a water-heparin solution. Our results indicate the good potential of superfocused diode laser beams for applications relating to optical trapping and manipulation of microscopic objects including living biological objects with aspirations towards subsequent novel lab-on-chip configurations.

Paper Details

Date Published: 3 March 2015
PDF: 7 pages
Proc. SPIE 9343, Laser Resonators, Microresonators, and Beam Control XVII, 93430Q (3 March 2015); doi: 10.1117/12.2078957
Show Author Affiliations
G. S. Sokolovskii, Ioffe Physical-Technical Institute (Russian Federation)
V. V. Dudelev, Ioffe Physical-Technical Institute (Russian Federation)
Vasileia Melissinaki, Foundation for Research and Technology-Hellas (Greece)
S. N. Losev, Ioffe Physical-Technical Institute (Russian Federation)
Ksenya K. Soboleva, Saint-Petersburg State Polytechnical Univ. (Russian Federation)
A. G. Deryagin, Ioffe Physical-Technical Institute (Russian Federation)
V. I. Kuchinskii, Ioffe Physical-Technical Institute (Russian Federation)
St. Petersburg State Electrotechnical Univ. "LETI" (Russian Federation)
M. Farsari, IESL-FORTH (Greece)
W. Sibbett, Univ. of St. Andrews (United Kingdom)
E. U Rafailov, Aston Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 9343:
Laser Resonators, Microresonators, and Beam Control XVII
Alexis V. Kudryashov; Alan H. Paxton; Vladimir S. Ilchenko; Lutz Aschke; Kunihiko Washio, Editor(s)

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