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Proceedings Paper

Tunable optofluidic microlasers based on optically stretched emulsion droplets
Author(s): Mehdi Aas; Alexandr Jonáš; Alper Kiraz; Oto Brzobohatvý; Jan Ježek; Zdeněk Pilát; Pavel Zemánek
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Paper Abstract

We introduce tunable optofluidic microlasers based on optically stretched, dye-doped emulsion droplets confined in a dual-beam optical trap. Optically trapped microdroplets of oil emulsified in water and stained with fluorescent dye act as active ultrahigh-Q optical resonant cavities hosting whispering gallery modes (WGMs) which enable dye lasing with low threshold pump powers. In order to achieve tunable dye lasing, the droplets are pumped with a pulsed green laser beam and simultaneously stretched by light in the dual-beam trap. For a given stretching power, the magnitude of the droplet deformation is dictated by the interfacial tension between the droplet and the host liquid which is adjustable by adding surfactants. Increase of power of the dual-beam trap causes a directly proportional change of the droplet stretching deformation. Subsequently, resonant path lengths of different WGMs propagating in the droplet are modified, leading to shifts in the corresponding microlaser emission wavelenghts. Using this technique, we present all-optical, almost reversible spectral tuning of the lasing WGMs and show that the direction of wavelength tuning depends on the position of the pump beam focus on the droplet, consistent with the deformation of originally spherical droplet towards a prolate spheroid. In addition, we study the effects of changes of the droplet and immersion medium temperature on the spectral position of lasing WGMs and demonstrate that droplet heating leads to red-tuning of the droplet lasing wavelength.

Paper Details

Date Published: 12 September 2013
PDF: 12 pages
Proc. SPIE 8810, Optical Trapping and Optical Micromanipulation X, 88101Y (12 September 2013); doi: 10.1117/12.2024252
Show Author Affiliations
Mehdi Aas, Koç Univ. (Turkey)
Alexandr Jonáš, Koç Univ. (Turkey)
Alper Kiraz, Koç Univ. (Turkey)
Oto Brzobohatvý, Institute of Scientific Instruments of the ASCR, v.v.i. (Czech Republic)
Jan Ježek, Institute of Scientific Instruments of the ASCR, v.v.i. (Czech Republic)
Zdeněk Pilát, Institute of Scientific Instruments of the ASCR, v.v.i. (Czech Republic)
Pavel Zemánek, Institute of Scientific Instruments of the ASCR, v.v.i. (Czech Republic)


Published in SPIE Proceedings Vol. 8810:
Optical Trapping and Optical Micromanipulation X
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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